Lower Temp Thermostat

Hey Everyone, I'm looking at upgrading my cooling system in prep for the upcoming season. I'm looking at doing a new waterpump, belt, thermostat, coolant flush, and a 3rd radiator. That being said, I'm currently looking for the lower operating temp thermostat (160*F) and the only ones I can find are the ones NOT in the housing. Can I purchase one of these and utilize my current housing, or do I need to find one that is in a new housing? I've been looking on LN's website for the lower operating temp thermostat and can't find it and I've found the insert on multiple places for a very good price. TL;DR - Can I use the same thermostat housing and replace just the thermostat with a new lower operating temp one, or do I need to look for one that is complete with the housing?

Pretty much, can I just buy link 1 or do I need to buy link 2? http://lnengineering.com/160f-low-te...e-install.html http://lnengineering.com/160f-low-te...nc-gasket.html

I always wonder what's the reason for LTTS. Isn't it better for the engine to reach optimum operating temperature more quickly? Cuz the fans aren't going to kick in at 160*F anyway; or do they? I'm just curious on the rationale.

With housing here http://www.pelicanparts.com/catalog/..._pg1.htm#item3 Or use a $17 tool here to remove the insert http://www.pelicanparts.com/catalog/...WATPMP_pg3.htm Or fabricate your own tool.

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Have you read the Hartech paper? http://www.hartech.org/docs/buyers%2...20part%205.pdf Starts at about page 21. Bottomline, the low temp thermostat will lessen the "heat stress" inside the engine under normal (non constant speed) driving conditions. Your engine will spend more time at lower temp on average.

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Thank you! You're always a good resource. I'll read it. But I bet most haven't. Only one thing: Somebody said - and I don't know who - that if the oil temp is below a certain temp constantly, it's lubricating ability is impacted resulting in cylinder wear. True or false? Not applicable?

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I think you may be referring to fuel dilution and excessive moisture in engine oil if the oil can't get to its normal operatimg temp to burn off those. That is correct so the low temp thermostat is definitely not recommended for ppl who drive short trips.

I have a lower temp thermo in mine which I installed about 6 months ago. I never run the engine unless I am travelling at least 10 miles anyway. More or less a DD.

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Yes, it is. Installing a LTTS in one of these engines -- any engine -- is about the dumbest move one can make. Testing has found engine wear increases quite dramatically as engine oil temperature goes down. This is not at engine start but after engine start while the engine is just running, doing its job. The t-stat is there to ensure the engine warms up within a reasonable time. Once up to temperature the air flow through the radiators controls the coolant temperature. At some point this is helped by the radiator fans. If you are uncomfortable with the max. coolant temperature and oil temperature your engine is manifesting under hard usage you need to consider more/better cooling. Adding a 3rd radiator and implementing a more aggressive radiator fan regime is what Porsche does when a car needs more cooling. 'course, the above is more difficult to do while installing a LTTS is relatively easy.

I know this has been discussed/argued forever, but I need to add my $.02 anyway... Once a thermostat reaches it's opening temp. and opens, it no longer controls anything (i.e. - water/coolant to engine block coolant passages) the water/coolant simply flows through it. It has no effect on the overall operating temperature of the engine except for taking longer to reach said temperature. Am I missing something here? Oversimplifying perhaps? I've read all kinds of "explanations" both here and on Renntech and none of them directly address this question - only sort of dance around it. It seems to me only the radiators can directly affect cooling.

A thermostat still controls engine temperature when it's open, it can close if it gets too cold or full open once it gets above a certain set point. If you didn't have one in the car, it would not get to normal operating temperature in most ambient conditions, or at least the cooler ones.

I think there are a lot of gross generalizations stated in this thread. But I'll add one more. A car engine's thermostat opening temperature (and steady state engine coolant operating temperature), has a lot to do with lower emissions, not necessarily lower engine wear. Higher temperatures generally means lower emissions. But it also means oil will thin out (you can get more wear) and other consequences. Would a car company want lower emissions at the expense of engine longevity? Of course they would. Most modern car engines run hot, and that is done for emissions reasons. b-man

I know we arent talking about "racing" engines per say, but given that both Hartech and Raby recommend the LT stat, I have to think there is some logic to this. Hartech sums it up as follows: WE CAN OFFER A LOWER TEMPERATURE THERMOSTAT THAT WILL MINIMISE OR HOPEFULLY ELIMINATE THE PROBLEM. This basically runs the engine cooler by about 12 to 15 degrees Centigrade (21 to 27 Degrees Fahrenheight) and (at a temperature more similar tothat which most racing engines (and more traditional older designs of sports engines) are run at. It makes no difference to theinterior heating system and actually slightly increases power output but the main benefit isthat when the car is driven under full power – even though the system as a whole is still comparatively slow to respond to sudden coolant temperature increases – the thermostat has now fully opened before the original normal running temperature has been reached (which increases coolant speed) and protects the pistons by lowering their temperature ofthe hottest ones and by this increasing the oil film strength If you want to read more start on pg 40 here - http://www.hartech.org/docs/buyers%2...20part%205.pdf

I knew this thread would go nowhwere as there are nothing new to discuss. Not sure why Macster felt the urge to call ppl dumb. To me, Jake Raby and Hartech are far from dumb. My used oil analysis actually shows LESS wear after low temp thermostat install, definitely not MORE wear.

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One thing that hasn't been discusssed too much in other low temp threads is gas mileage. Gas mileage could go down a bit using lower temp thermostat. Don't believe me? Trying running one without a thermostat and report back on your gas mileage. My factory spec one has been doing just fine in my engine for the past 125k miles. I don't feel a need to fix something that ain't broke, but that's just me.

My Cayenne started taking a long time to warm up and was running as low as 62C on the highway and made about 85C in traffic. Oil temperature was no different and remained at the 90C it always runs at; gas mileage really went to sh*t though. Thermostat has been replaced and I'm picking it up tomorrow.

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Again, once the thermostat opens up during a drive, I highly doubt that the engine temperature will lower to a point where it will close up again. Therefore, after the engine is warmed up, the thermostat function is done - I think. So while I truly respect the source, it doesn't make sense to me.

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Don't the engines pretty much stay warm all the time in that part of the world? You could probably just explant it and still be OK.

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Companies with a lot more skin in the game that Hartech or JR have done quite a bit of research on the ideal temperature ranges for engine operation. Tests have found as engine temperature goes down wear increased dramatically. Hartech apparently tested two cars... While I note Hartech claims thousands of cars are at risk from some horrid problems running the factory T-stat yet Hartech offers to sell every owner an extended service/warranty package. Run whatever T-stat you want. I do. Mine just happens to be the one sanctioned by the factory.

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The thermostat is not a digital device that it's either open or close. It can open partially at some specific temperature. Also it's located AFTER the radiators where the coolant has already cooled down. http://lnengineering.com/index.php/p...nc-gasket.html

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I observed no mpg difference for the type of driving I do. 10 miles local traffic twice a day. YMMV of course. I'm pretty sure if you remove the thermostat you will see lower mpg.

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You really need to read the Hartech Article. I've had the LTS (and housing from LN) in my car for over 4 years now on a daily driven 2003 C2. Here in Northern Delaware (just outside of Philly) we get all the seasons and all the various types of Weather. It was 11 degrees yesterday and it can be 100+ in the summer. I have noticed no fuel economy loss, no signs of heavy engine wear, and no issues with the cabin heat getting up to a nice hot temperature. I change my own oil (cough cough Macster) and run every other sample through Blackstone labs. I've owned the car for 5.5 years and 40,000+ miles. The stat has been in place for 4.5 years and 36.XXX miles. The low temp stat can't be called "the dumbest move one can make" simply do to the fact that is a blanket statement across all vehicles. You need to do what is appropriate for your vehicle. And in the case of the normally aspirated 996 (you may not even be able to make the same claim for the Boxster or 996 Turbo) converting to a LTS is a beneficial upgrade. Read the Hartech Article!

Everyone realizes that the "article" that is being referred to is just a long drawn out ad for Hartech right?

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So you truly believe that these vendors are trying to get rich by selling this $100 part? And JR is risking all his reputation by putting in a part that will create MORE wear and no benefits in all the M96 engine he builds/rebuilds? And Porsche must be dumb too because they went with a lower temp thermostat for 997s?

And still no one has directly answered my question. "A thermostat still controls engine temperature when it's open, it can close if it gets too cold or full open once it gets above a certain set point." Nothing personal and with all due respect Paul, that's just silly - how could it possibly get "too cold" with the engine running? Simple - it can't. And, no the thermostat doesn't "control temperature" once it has opened. [/b] "If you didn't have one in the car, it would not get to normal operating temperature in most ambient conditions, or at least the cooler ones. "[/B] Duh... "So you truly believe that these vendors are trying to get rich by selling this $100 part?" Companies do it all the time. Many companies exclusively sell merchandise that's very inexpensive (Dollar General comes to mind) and they're very successful (rich). Perhaps this is an anomaly in the Porsche world (no fooling...) but I'm sure this isn't the only part they're selling, and the margin on a $100.00 Thermostat must be huge... **So, the challenge stands to the EXPERTS with all due respect - Please explain how a thermostat can affect/control/reduce (whatever you want to call it) the operating temperature of an engine once it has opened fully to pass coolant. I don't pretend to know the answer unequivocally - I'm just very skeptical, and it's my feeling that it can't (and no one has satisfactorily explained otherwise).

Read all the points for/against a low temp t-stat and had to decided to go with one. Until I showed up to my indy to have it done (along with new water pump).....he politely told me that he will NOT do it. Yes, he read all the studies and articles but simply did not buy it. Oh well, I have a factory t-stat in my car now. P.S. Anyone remember what temps the OEM vs low temp opens? Is it 180 vs 160?

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I believe it opens up at 180 but the fan kick in temp is 192 degrees if I am not mistaken.

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Stock thermostat: starts to open at 186F and fully opened at 210F. Low-temp thermostat: starts to open at 160F and fully opened at 185F.

It always amazes me how with this part it seems everyone is in one camp or the other and very passionate about it. Makes for long controversial threads. Will there ever be a consensus?

Of course no consensus Other dead horses: I*S failure (5% or 10%?), best IMS solution, engine oil, transmission oil, n-spec tires, short shifters, anti-seize on spark plug or not, brake vibration dampers or not, clutch helper spring or not,... All have very little to no scientific proof to convince people one way or the other.

one could argue it as a regional or seasonal thing in warmer climates or in heavy stop and go traffic, prefer the lower LTS here in the north where temps rarely break 100, the stock would make more sense mine is slow to warm anyway, taking 6-8 minutes to reach full temp

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You missed coolant and I'm sure a few others. Never heard so much bickering between guys honestly before I came here. People should use what works best for them and what they believe in but don't bash others for doing so. Kinda like Religion...

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Well said! Religion did cross my mind

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Actually, I'm not passionate about one way or another. I'm simply challenging so I can gain knowledge. Actually based on all the info Ahsai has graciously supplied in this thread I'm leaning toward an LTTS. Dude, I may be a PITA with my questions but I'm very appreciative of everyone's input. Thanks! On other news, OP, did you get your question answered?

"Actually, I'm not passionate about one way or another. I'm simply challenging so I can gain knowledge. Actually based on all the info Ahsai has graciously supplied in this thread I'm leaning toward an LTTS." Information? Really? More like anecdotes at best... Not that I don't like anecdotes... I've been thinking about this issue today (while building my workbench) and the only possible theory/possibility/explanation I can come up with is that - due to the low temp thermostat opening sooner, there is less thermal shock to the crankcase/heads due to the cold coolant rushing into the (less) hot passages. I suppose it's possible that in extreme cases this could cause very thin sections in the heads to crack.

From reading this entire thread, my main observation is: No one has any evidence, statement, etc. that a low-temp thermostat OR a regular thermostat will brick and engine. Maybe some evidence that one may or may not have the potential to do so.. but ultimately, it sounds like no matter what avenue you go with, as long as your thermostat operates properly - your engine will be fine. Maybe I'm over simplifying.

Thats assuming your cylinders aren't compromised from the factory. Wear isn't the reason why we developed the low temp T stat, it was to directly attack cylinder deformation issues that plague these engines. Macster, ever installed a thermostat in a Porsche engine before? Ever carried out a single comparative valuation with the same engine and two different T stats, back to back before?

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You truly believe all automakers are clueless about engine coolant temperature and the role it plays in all phases of engine operating and all have opted to run T-stats that subject the engine to the wrong operating temperature and two indy engine rebuilders have uncovered this? As for the 997, the lower temp T-stat is in place to open sooner not because Porsche decided colder was better but to allow the other DME controlled T-stats in the engine control the coolant temperature of the various regions of the engine/cooling system they control. The word I get is Porsche will implement this change in coolant temperature control in all engines over time. Porsche is aiming towards more precise control of the coolant temperature during all phases of engine operation. As such, I expect at some point Porsche will do away with the old fashioned T-stat entirely and just let the DME and its population of T-stats manage coolant temperature. The old fashioned T-stat is just there in case there's a problem and Porsche can install a higher opening T-stat and disable the DME control of the other T-stats leaving then in their fully open position.

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Jake thanks for chiming in on this. Does your low temp t stat operate only as full open or full closed? What is the theory behind its operation and ability to curb cylinder deformation?

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No I have not installed any T-stat in a Porsche engine. I have installed a few over the years in other engines. Might mention that even then there were a few who would recommend installing a low temp T-stat. It never really caught on and I note automakers could have at any time elected to install one as matter of course, but have chosen not too. My recommendation to stay the factory T-stat is based on Porsche's testing, not my own testing. My info is Porsche runs a number of test mules thousands of miles in all kinds of climate conditions, from the heat of the desert in the USA southwest (or in South Africa where the local government gives Porsche -- and other cars makers -- carte blanche to drive at high speeds with impunity), to the sub-freezing temperatures of northern Norway in the winter and all temperatures in between. These test mules are heavily instrumented and carefully monitored and checked by a team of Porsche techs for any issues at all. By overruling Porsche on this matter, then it is your testing that comes in for consideration. Has your testing even approached the level of testing Porsche does prior to one model's release?

Jake, I'm glad you weighed in on this, as you're one of the "experts" I hoped would comment. Please explain in layman's terms via cause/effect, what the advantage to the low(er) temp thermostat is. Thanks in advance!

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Cylinder deformation issues? Well, lets consider this then. The low temp T-stat affects of course the coolant temperature. It does not affect the combustion temperature. Thus the surfaces exposed to combustion still get exposed to the same high temperatures. With a low temp T-stat in place with the resulting slower warm up and the engine being slower reaching temperature equilibrium and this temperature being lower than it would be with the proper T-stat installed the cylinders run cooler then they would otherwise. Yet the piston crown still gets exposed to the same heat of combustion as before. So the cooler cylinder remains smaller in diameter while the piston still grows in size from its exposure to the heat of combustion. This works to decrease the clearance between the piston and the cylinder wall, which is already quite small to begin with. Couple this with cooler oil there is the real concern, at least on my part, about the cooler cylinder with the hot piston being subjected to marginal lubrication. Oil is not pressure fed to the cylinder wall/piston interface so any oil that gets there does so by splash and flow on its own. But now the oil is faced with flowing into a smaller gap and with the oil at a lower temperature than it would have otherwise. I note Porsche has a caution to avoid high RPM (>4K) operation until the engine is warmed up. However, with the low temp T-stat in place the engine doesn't obtain the operating temperature Porsche expected when it set this cold engine RPM limit, yet as far as I know no recommendation to use a lower temperature T-stat has come with any change in this RPM limit to take into account the colder oil arising from the lower temp T-stat. Someone driving around with the colder engine now decides to use a lot of throttle. Of course combustion temperature goes up as then does the temperature of the piston and naturally the piston grows in size. But the cylinder wall already cooler than it would be otherwise has less margin of clearance so my concern would be the piston grows larger and reduces the clearance between the piston and the cylinder even further possibly to the point of oil film break down and metal to metal contact. It would appear then to address some cylinder deformation one is accepting whether he realizes it or not the increased risk of cylinder wall/piston and ring clearance lubrication issues.

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Understand that all of that "expert" engineering about engine cooling done by Porsche is motivated primarily to comply with federal emmissiions. If Porsche doesn't comply with emmisions, they can't put a single car on the market, Cars that run hotter have less emmisions so its a no brainer Porsches are engineered to run hot. Hottter running is not best for engine longevity, but engine longevity is not first on Porsche's list, emmisions are since engine longevity doesn't prevent Porsche from putting a car on the market, but emmisions will. So its all a question of priorities. Porsche rocket surgeons have designed a fantastic cooling system that assures it complies with emmision standards, not necessarily engine longevity. The first thing Porsche has to do is get a car to market, they can deal with longevity problems later.

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When I highly respect the expertise of Porsche, I also have an open mind. I understand in real life, they need to make compromise and there may be cases not tested due to time to market constraints, etc. MSFT has all the expertise in software development. Does that mean their products are bugs free? If your theory was true, we should see all the engines with the low temp T-stat throwing rods and blowing up left and right. The UOA metal should also shoot up the roof. Sorry but I didn't see either. Re the 997, the fact that the engine uses a low temp T-stat means there a region where the low temp makes sense. Otherwise, they couldd have just reused the regular t-stat.

I know that the first priority of the car companies has to be to meet the emission regulations set by various governments, not engine longevity. I went with the low temp thermostat because I believe Jake and some other experts that have devoted a good portion of their lives to improving the longevity and reliability of these engines and said its the better way to go. Thats their opinion and I'm going with it, they didn't have to meet any government regulations and were concerned only with the other issues that affect the 996 motors.

Macster, If I agreed with all of what you said, unfortunately, we'd both be wrong. You didn't answer my question about personal experience with Thermostats? I have personally carried out the development of the LN Tstat, starting prior to 2007. In that period of time we have ran street engines with stock thermostats on the street and then exclusively on the track, then torn them down, measure taper and ovality, then installed a Lo temp unit and done the same thing. I have also swapped the roles and started a fresh engine off with a low temp stat, then swapped it later for a stock one, and watched the values both ways. Any engine I create will have a Lo temp LN unit (not any other) and will get that from day one, if it is removed, my warranty is void. Thats how strongly I feel, based on direct experience. Lots of the hot weather test work was done here, and we ran an engine for as much as 160 hours straight without shutting it down. The cold weather testing was done at LN, and Charles and I tackled it together, most of that was done in -10F temperatures, with some done at -27. Last year we took advantage of the super cold weather to prove the Cayenne low temp Tstat. That even goes for my customer in Russia, who has been running one since 2009. Lots of reasons why the Tstat is set the way it is at the factory, primarily for the hot restart emissions testing, as its very important to keep the coolant hot for as long as possible. This is why aircooled engines failed so horribly, because they cooled down too fast when shut down (after a brief temp spike just after shut down). My hypothesis is this period after shut down, is when lots of deformation issues occur. Nothing has proven to keep cylinders straight and more round than reducing coolant operating temps by a few degrees. This is especially true for cylinders 2 and 5, where they are situated between cylinders, and see the hottest coolant, for the longest period of time. Its not just the overall temperature of a Tstat that matters when developing a better mouse trap. How much the unit will bypass when cold, how soon it starts to open, and the temperature that it is fully open are all what required special attention. I see factory engines with bores .010" oval by 100K miles, which is ridiculous. This is our normal findings, as Charles measures every block that goes to LN before machining, and notes mileage. Generally bore will gain .001 ovality and .0005" taper per 10K miles. When developing the low temp Tstat we faced lots of ridicule, but we've never seen someone remove the low temp unit and go back the other way. The general consensus of "if the factory didn't do it" is the biggest wall that a developer has to face. Quite frankly, I don't give a damn what the factory did, or why they did it. Yes, coolant temp matters in regard to enrichment, as well.. There's a point where the CLT can make serious power, I have observed a 15 degree window where the engine makes the most power, and coincidentally, the engine moves to a different fuel map for this window. You learn this from having to chase maps while developing ECU flashes from scratch. When Beth was Land Speed Racing her 996 I would work very hard to keep the car at an exact temp, around 4-6 degrees below the sweet spot while we were in line to make her run. That meant foreign the car up, shutting it off and doing what we could to keep the engine where I wanted it to be. When she'd launch, the entire run would usually complete before the temp was out of the sweet spot, netting the most power. It took me about 6 trips to the track to figure this out, and hours of studying datalogger and dyno plots. All that said, still trying to be on my behavior around here and trying to help. Its kind of hard to be neutral when you developed the part that people are slamming; even though they have zero direct experience with it. This Tstat was another product that was developed first for my engine program, then began to be sold individually.

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That's a good explanation. Balanced delivery and what seems like a fair amount of real data and research... I don't believe I "slammed" anything even though I certainly questioned the wisdom of the Low temp. T-stat.

One of the things that Porsche worked hard join with the 987/ 997 was running temperatures. I am sure that they saw the impacts that these things were having on engines when they were returned as cores. The way the cooling system is routed in the two models is drastically improved. The result is cooler peak temperatures, especially on the track. I do not gain this data from OBDII or the factory gauge, I install 28 channel data loggers to gather the data, and they are driven by stand alone sensors. What the factory wants us to see through calculated CLT values, in the gauges, are different than actual, raw values. Here are some examples of how the cooling sub- system was altered through the 9X6 and 9X7 models, as a comparative. These came from my M96/ M97 Engine Mechanical Class Presentations. There's a teaser in there too..

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Define "hotter". I am not recommending in place of a LTTS installing a hotter one. The one the engine comes is what I recommend. As I have covered before testing has found engine wear increases with lower operating temperatures. It is not like these engines are operating at extremely high temperatures. They are operating at temperatures that have been found over time to deliver good engine life and performance. While emissions compliance plays a large role in engine design Porsche -- and all other auto makers -- must still deliver satisfactory engine reliability. I note the Chevy Vega with its horrible engine reliability died a quick death. No sane car owner is going to turn around and buy another car from the same automaker if the first car suffered a premature engine failure. The rest of your comments on engine longevity are simply nonsense and deserve no further comment.

This sounds like one of those discussions that needs to simply come to an end. I have a lot of respect for the primary participants, and would really like to keep it that way. Thanks for everyone's opinions, but can we stop now?

[B]I READ this exact same thread 10 years ago....except it was on HTT...a former motorcycle thread for Harley's. Oil coolers or not for Harley's!?? I-fecking-dentical to this whole steam of conversation, experts all over the country saying DO and others yelling DON'T! Absolutely hilarious! Just like a group from my last homeowners meeting deciding which paint to use on the fences, and the gravity and in depth analysis of opinions as to why choose A or B. I have no skin in this game, but @ 40K INSTALLED a new water pump & cooler T stat and installed an oil cooler on my bike @ 1K. AM I GOING STRAIGHT TO HELL!!! [/B

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I agree, I've heard it on other forums also, like which oil to use etc. Its a never ending discussion but in the end you pick a side and run with it. Of course I ALWAYS pick the CORRECT side.

I think some one needs to make a 170* thermostat, surely that would combine the best of both the chocolate and peanut butter sides of this debate!

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^this, seriously. For me, my car is and will remain stock, and parts replaced are oem. I really don't pretend to know better than those who built and designed the car and all of it's systems.

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Oh dear another one who thinks the thermostat doesn't control temperature...

If you can't agree with what I posted then apparently the laws of physics are being violated in Porsche engines. Personal experience, beyond just replacing them, with T-stats? No. But as I pointed out I'm not the one advising owners to switch away from what the factory installed to what is believed to be, pardon the expression, the hot setup, a lower temp T-stat. The problem with testing is that it is impossible to cover all scenarios. While running an engine constantly with a lower T-stat in place didn't turn up any issues, there are a number of different usage scenarios that could result in a different outcome. To make a blanket statement that all engines of a specific model require a different/lower temp T-stat is to assume all owners will use the car in the I think obviously optimum manner in which you tested the T-stat. I think this is a dangerous assumption to make. I guess what it boils down to is when you have been in business for a long time and have sold thousands of cars/engines and have stood behind these over the years for 50K or even 100K miles I would be more comfortable with your recommendation regarding installing a lower temp T-stat (although I have to wonder if doing so could in some regions of the USA run afoul of emissions regulations?). Frankly, I have to say that if I believed I had to make such a change in the engine from any manufacturer I would simply avoid buying the car in the first place. I am way beyond the desire to have to customize/mod an engine from which I expect to obtain what I believe to be satisfactory performance/service life in order to get this satisfactory performance and service life. I prefer my cars deliver this out of the box, so to speak, rather than require extra work on my part.

Go here: http://www.pelicanparts.com/catalog/..._pg1.htm#item3 $62.25 for LN Engineering part

deleted, oops, wrong post

There is another way to look at the question of a low temp thermostat vs. an OEM thermostat for M97 engines, and that is to look at what Porsche has done for the 981. In those cars, there is a map-controlled thermostat (probably made by Wahler) as part of the Thermal Management System. This thermostat has two settings, a normal setting resulting in opening at a higher temperature, and a lower temperature opening (when the sport mode is activated as I recall). In the sport mode a small electric current will "pre-heat" the thermostat so it opens at a lower coolant temperature resulting in a decrease of about 20F under �normal� conditions (for example see http://www.planet-9.com/981-chat/897...nterlocks.html ). From a Wahler brochure ( http://wahler.de/fileadmin/wahler/Do...schuere_en.pdf ) �Electrical heating opens the coolant circuit earlier in situations of very increased performance requirements. Depending on the preset the engine can be operated hotter than previously usual, for instance at approximately 100 ̊C to 110 �C in partial load conditions. This results in a consumption advantage of 1 % to 2 %. Under full load the temperature is reduced to approximately 80 �C, which allows the performance � especially the torque � to be measurably increased by approximately 2 % to 3 %.� It should be noted that the temperatures mentioned above are examples and may not directly apply to 981s. In 987 Caymans, the choice is either a low temp. thermostat or an OEM thermostat, but not both. It seems reasonable for choose the low temp. thermostat for its better performance and for the reasons well described by Hartech and Flat 6 Innovations. It should also be noted that Porsche places the thermostat on the coolant return line and not on the outflow line. One way to think about this is that Porsche is more interested in keeping the engine temperature from becoming too low (perhaps at the cost of performance, bore scoring and cylinder roundness) while thermostats on the outflow are more focused on not letting the engines become too hot.

I have a LN low temp Thermostat. I do not track my car, but I do run it's legs out. My issue with the OEM thermostat and the cooling system as a whole in my 996 was that after spirited drives, if I was stuck in traffic for any amount of time, my temp gauge would climb to higher than one would like levels. My options were to add a third radiator (which I still might do) or change out the thermostat when I was having my engine rebuilt. I chose the thermostat and my car does not get nearly as hot as it had previously. Yes my radiators are good and yes my fans work. This really seems like a silly argument, but on this forum, it doesn't surprise me one bit. As they say, opinions are like ********, and everyone has one.. including me.

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Youve got other problems. I can drive mine like I stole and then idle for 20 mins in traffic and never get above 212 degrees or so...With the outside temp at 110 degrees.

Alright peeps. I know this is going to turn into a sh*t fest about low temp thermostat real soon but here it goes. I just did water pump, coolant flush, and LTTS on Thursday and drove the car to Vegas. The verdict: LOVE IT!!! I feel like the engine warms up more gradually and smoothly and the temperature really stays more consistent. On the highways, the needle was smack in the middle even a tad below at times. All this at 106 F temperatures. I highly recommend it. Money well spent.

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Why don't your revive the JG DT40 thread too and tell us your impressions there as well.

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Well, I have nothing but good things to say about the 996.

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That's because you're trying to sell it. That wouldn't be a conflict of interest if you were bad mouthing it AND trying to get top dollar for it now, wouldn't it? :0

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To tell you the truth, I've given it a thought at least a few times to just take it off the market and keep it for as far as I can. We'll see what happens in that department.... Also let me correct you. I have listed it for sale not I'm trying to sell it. Subtle difference but an important one.

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Sorry for the old bump. Did you install the Motorad or LNE thermostat? I'm curious to the difference between the two.

So not trying to hijack the thread, but this question seems to be germane to this discussion: If the thermostat is stuck closed will the radiators in the front ever get hot, and will the fans not come on? I got a flashing temp light which according to the and engine fan inop message, which according to the Bentley manual means low fluid - not - or inop fan and it runs fine. The engine temp doesn't peg but it has been cool. My radiators are cool to the touch and the fans aren't running in the front when I get the message.

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If the T-stat is stuck closed the radiators won't get hot. They may get a bit warm, depends upon how closed the T-stat is. But if it is truly closed I suspect the temperature and pressure will build to the point something lets go, like a hose (or clamp), or the coolant tank splits, or the cap starts blowing vapor, or a head gasket fails, or a head cracks. If you suspect a stuck T-stat you should not delay in getting the car flat bedded to a qualified shop and have this diagnosed and dealt with. If the meaning of the flashing light is low coolant why not when the car is cold open the cap and check? Be aware that the coolant tank will become discolored over time and what from the outside you think is the coolant level is just a water stain. I have found to really be sure of the level of coolant in the tank I have to remove the cap -- wehn the engine is dead cold! -- and remove the screen and stick a wooden dowel or something down and visually confirm where the level is. If it is low you can add distilled water to bring the level up. Once when the light came on with my Boxster I added a gallon. If the level is low and there are no leak signs -- to really be sure you have to get the car in the air so you can check for coolant leaks from under the car as it is the areas under the car most often coolant leaks appear, it could be the cap is leaking. In the case of my Boxster, at least once, it was the cap that was leaking, letting vapor escape. Another time it proved to be the coolant tank had a split in it.

The coolant level is fine. So that is why I question the coolant issue. I looked at some other threads for the temperature at which the thermostat is supposed to open. Since it is winter, the car has not gotten "hot" just barley over 180 according to the gauge. I am going to check it on the AC display and see what it is reading. My understanding is the thermostat is supposed to open somewhere over 180 correct? Secondly the engine fan comes on and stays on, I think this might be where the sensor fell against the engine. I read that someone else's did that. I am just not sure what I am looking for. Thanks for the assistance

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TO answer your question, Yes, the fan will come on even if the thermostat fails shut. if your fan is running continuously after warm up, that is likely because the short coolant circuit (with thermostat closed) is overheating. You should also see high temperature on the gauge. If you are sure the car is not overheating, it is possible that one of the temp sensor is out. does the car idle high when the light/message comes on?

The temp gauge doesn't go above something like 200, I can short the front fans into running. I will check the temp sensor that seems to make the most sense, but it still doesn't explain why the front radiators aren't getting hot...

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Radiators are not getting hot because the thermostat is not opening......this is a critical condition, I personally would replace the 'stat (and waterpump whilst I'm in there )

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The factory T-stat is intended to open at IIRC 86C or about 186F. The temperature at which the fans come on low speed can vary from MY to MY (possibly) but my observation with my Boxster (and I think with my Turbo too, but you know I can't recall checking the Turbo) is the fans come on low speed when the coolant temp gets to 212F and switch off when the coolant temp drops to 205F. If the coolant temp continues to rise the fans switch to high speed when the coolant temp reaches 216F. The fans stay at high speed until the coolant temp drops to 205F. If the A/C is switched on the fans run all the time. The fans can be switched to high speed under some special conditions, something to do with if the A/C requires max. cooling. Depending upon the MY you may not be able to view the coolant temp via the heater/AC display. What I use is an OBD2 code reader/data viewer that I connect to the OBD2 port and obtain various engine and engine sensor telemetry of interest. Among these is coolant temperature. If you are sure the T-stat is working ok and the cooling system is working ok and the coolant level good you can test fan operation by driving the car around town -- with the A/C off -- until the engine is thoroughly warmed up. No need to get all crazy just drive at legal speeds in residential areas. Back home in the driveway then raise the engine speed to say 1500 and hold. After a while the coolant will get hot enough to trigger the fans to come on at least at low speed. You can have an OBD2 code reader/data viewer hooked up and observe the coolant temperature -- or use the heater/AC display if that feature is avaiable in your car. When the coolant temperature reaches 212F the fans should be on. You can let the engine speed return to idle and let the fans continue to run and observe the coolant temperautre fall and then the fans shut off when the temp drops to 205F.

I was thinking about that LN low temp thermostat or a 3rd radiator kit for cooling purposes in Florida's hot summer. Any thoughts on this as I am new to the porsche world. Thanks, michael