Too cold

The temp in my 996 is very temp dependent. Gotta love Ohio weather. On hot days over 90 degrees the temp gauge can get just above the 0 in the 180 degree temp gauge. On moderate days of 60-70 degrees runs just below the 0. On cold days like this week of 10-20 degrees it does not get past the 8. Average operating temp is usually between the 8 and 0 in the spring, summer, and fall which I assume is the normal operating temp. I do have a low temp thermostat installed. Is it bad in the cold if it never comes up to operating temp?

Quotes source post: 11821616

I installed the lower temp thermostat when I was doing my water pump about a month ago. We are below freezing now and no matter how much I push the car the temp never gets to the 180 segment. The needle stops just before the 8 of the 180 same as yours. So I would say a definite NO to your question. On these cold morning starts I always let the car idle for about 5 minutes before driving off from a cold garage. Very rarely under normal driving do I rev over 3500 during changes and settle off between 2500 & 3000 revs.

why did you put in a low temp thermostat? I live in texas and it routinely gets over 100 degrees here and I drive my 03 like I stole it and can still sit in traffic and the engine temp never gets above 210 degrees. The motor is designed to run at that temp.

Quotes source post: 11821616

First you can't rely upon the temp gage for coolant temperature. The coolant temp gage is really more for show than go. You need to connect an OBD2 code reader/data viewer to the car's OBD2 port and monitor coolant temperature in real time. After a while you can develop a feel for the coolant's temperature from where the needle is based on observing the actual temperature using this OBD2 code reader/data viewer. The t-stat does not play a role in the engine's operating temp only how long it takes to get there. It is better for the engine to get up to operating temperature as reasonably quick as it can and it is bad for an engine to not come up to operating temperature. As I have covered before engine wear goes up as oil temperature goes down. This has been documented in lab settings. I won't type in the entire chart but at 210F over a 60 hour engine test cylinder wear was measured to be 0.0003 inches. At 180F over a 60 hour engine test cylinder wear was measured to be 0.0005 inches. At 155F 0.001 inches. It is imho crazy to install a low temp t-stat in these engines. The engine coolant temperature the engine reaches is a function of how hard the engine is working and the cooling capacity of the car's cooling system. In the case of my Boxster the highest coolant temperature I've observed is 226F and this in 116F heat or just driving around town in stop/go traffic in while not 116F pretty high ambient temperature or on a moderately warm day -- high 80's low 90's -- when pushing the car hard in the twisties. The coolant doesn't get any hotter not because of the t-stat but because the car's cooling system can carry away the heat and keep the temperature at or below 226F. What you are experiencing is the longer amount of time the engine takes to get to its operating temperature due to the lower temperature t-stat. This is compounded by these are cold blooded engines to begin with. Even with my Boxster's factory t-stat installed during the winter starting the engine and letting it idle the usual minute or two -- until the secondary air injection pump shuts off -- and driving the car it can take upwards of minutes (15 or so) before the engine is at its "operating temperature". I put this in quotes because the engine's operating temperature is dependent upon the ambient temperature. For instance in 116F heat (in southern AZ one summer) the engine's operating temperature was 226F. The coolant temperature reached this and stayed at this temperature until I managed to drive out of the region (the southwest) and into slightly cooler temperatures. During the winter months the coolant temperature would struggle to reach and remain at 185F often staying closer to 180F. My recommendation would be to get an OBD2 code reader/data viewer and monitor your car's coolant temperature. Based on what I think you observe I expect you will regret installing that low temp t-stat because the engine is running even colder than it would with the factory t-stat installed.

I did notice that operating temp depends on ambient temp. Not used to seeing that. The rest of my cars run at the same temp regardless of ambient temp. Unless it's really, really cold. Low temp thermostat came with the rebuild. Didn't question it at the time. I understand thermostat doesn't make a difference on final operating temp when the operating temp is above the setting of the thermostat, just how fast it gets there. But will the lower thermostat stop it from getting to operating temp in cold weather? Guess I need to know what the final operating temp is. Is the temp in the secret menu accurate or do I need to get the OBD one?

Quotes source post: 11823226

If you are referring to the temp readouts that you can obtain from your climate control system screen on gen 1 cars, then yes the temps should be accurate. An OBD reader would get its info from the same sensors. I've used this during hot weather to monitor engine coolant and oil temps and I have noticed that stop and go traffic and idling in warm weather seems to send the coolant temps high quickly. If your thermostat is working correctly, it should have no effect on how quickly the engine gets up to temp regardless of whether it is a low temp or standard temp unit. In other words, it should restrict the flow of coolant from the cooling system until the coolant warms up enough, and then it opens incrementally to keep engine coolant temps stable.

Quotes source post: 11823155

What? Operating temperature is not controlled by the thermostat? The thermostat very much controls the operation temperature under "normal" driving conditions. The only time at which the thermostat has no influence is when you are stationary, at this point the operating temperature is determined by the fan switch-on temperature (unless you just happen to have a lot of wind coming the right direction). If you don't believe me, I suggest you remove your thermostat temporarily and see how cold your car runs. Furthermore, I suggest you work your way through the most excellent Hartech papers on these engines, which analyze very accurately what the problems with overheating are, and wny the low temp thermostat is a good idea (no I will not enlighten you, you need to do some research). I also find your "test results" highly interesting, as from around 2000 onwards, German manufacturers lowered their engine operating temperatures from 92-95 deg to 81-85 deg C (with slight variations + or - depending on model year changes). 180 with modern oils is entirely sufficient for adequate lubrication, and will prevent many of the bore scoring issues which you are seeing with nikkasil, lokasil and other *.sil engines. By fitting a lower temperature thermostat you are helping the insufficient cooling on the 456 side cylinderheads, especially after the car has been sitting in traffic for a long time, followed by a fast take off when traffic clears, something everyone on this board does I am certain. Your analysis of the low temperature issues of oil are also incorrect, there is no issue with running a modern oil at 80/180 deg C/F, as lubricity is not compromised in that temperature range, it is when they get into the 210+ range that problems start arising as the oil becomes too thin to maintain a suitable oil film.

Whoa. Didn't mean to start anything. What he is referring to is that the thermostat opens at either 165 for low temp and 185 for normal (if I remember correctly). Once the thermostat is open you get full coolant flow. The operating temp is above the temp of the thermostat. If I understand thermostats correctly, which I think I do, if you take the thermostat out the final operating temp will be the same, but it will take forever to reach operating temp because you will have full coolant flow the entire time. The thermostat does not regulate the temp of the engine, it is just a valve that opens and closes at a certain temp. My concern was with a 165 degree thermostat in the winter it open sooner and lets in a bunch of coolant and the temp may never reach 185 - which I was wondering if this was bad for the engine, to run at less than that. I am going to do some monitoring with the digital gauge and see what I get. If it gets over 185 then I won't worry.

Welcome to the scored cylinder club!

The reason I changed to a lower temp thermo. I was changing my water pump and had to remove the thermo to get the pump out. Thermo was cheap enough, so why not? An engine running at a lower temp, kind of speaks for itself in my book. By opening earlier. The engine runs cooler at least for a short time. That can't be bad.

dgjkl6 -- you've got the thermostat function exactly correct. Full marks, go to the head of the class The thermostat is closed only until the WATER temperature comes up to 180F (160F-165F for many low-temp thermostats), after which it is fully open and not longer does anything useful. The whole point of having the thermostat in the cooling system in the first place is to accelerate the rate at which the motor warms up. It is NOT there to keep the engine cooler. The motor needs to come up to a temperature where the thermostat is wide open. If the motor isn't getting that hot then a whole host of issues related to high levels of unburned fuel and condensation in the oil become relevant. FWIW, this is one of the reasons manufacturers recommend changing oil more frequently on cars making only short trips.

Quotes source post: 11824130

Really? You went there. Krazy, I feel like we have bonded but we have different theories on ownership. I drive my 996 everyday except for a few circumstances when I drive the Excursion: 1 - taking more than 3 kids 2 - more than 6 inches of snow 3 - going on the morning Starbuck's run for the family (Excursion has 6 cup holders I can reach from the driver's seat, and even if it spills it's OK) I have over $40,000 invested in my 996 and the only way to get my money back is to drive and drive and drive (I have 10,000 miles on it since the rebuild)

Not exactly. Depending how much heat the coolant looses through the radiator. If it's enough to bring the engine down to the rating of the thermostat than the thermostat stays wide open but if it goes below it, the thermostat will start to close. The job of the thermostat is to regulate the engine's temperature, unless the ambient air is so hot that the returning coolant from the radiator is above the thermostat's rating. In that case the engine will slowly get hotter and hitter until the fans kick in. At that point the fans become the thermostat. Or at least that's how I understand this.

Quotes source post: 11824430

I understand what you are saying. I just assumed the thermostat was more of a on off valve than a regulator. But you are right. I bet there is a range where the thermostat starts to open and is fully open so it does regulate the temp some. But the operating temp on all my cars is well above the thermostat opening temp. I am going find the old grand prix thermostat I have laying around and run an experiment and boil it is some water and check the opening and closing temp. Better yet, I have a science project for the kids today.

Gotta love you tube. Didn't need to do the project. https://video.search.yahoo.com/video...2Cm%3Asa&&tt=b Looks like it's a valve and is fully open at operating temp.

Quotes source post: 11824493

To clarify, a thermostat starts to open at it's rated temp and reaches it's fully open status probably 5-10 deg above that, here is another great video showing this: How Thermostats Work - YouTube

Quotes source post: 11824201

Everything in this statement is false. Engines are designed to operate in a specific temperature window. If you operate the engine out side of that window you are doing damage to the motor.

Quotes source post: 11827120

Welcome to Hurdi's Hunches, a gut-based approach to 911 maintenance and repairs.

Quotes source post: 11827120

Great comment, shame it is completely useless without any references as to what the "correct operating temperature" should be, or accommodating any of the other myriad factors that go into assessing the harm/good done by running the car a few degrees cooler.

This has been beaten to death in the past but one thing some people look past is potential increase in fuel consumption, especially for short in-town trips. I can't speak to the 996 since I've stuck to the stock thermostat but I have experienced this in my BMW before.

Quotes source post: 11827478

This should be common sense in a technical forum for cars. They need to do their own research-I'm not gonna do it for them.

Quotes source post: 11829609

Whose common sense? Yours? Mine? what standard are you going by, I find your statement to be inaccurate at best, and that doesn't have much to do with common sense, but an understanding of how cooling works, how lubrication is affected by temperature, the issues the water cooled engines have, and so on and so forth. Of course me stating that I KNOW, doesn't help anyone else, and neither does your throw away statement. Remember you are on a forum, the purpose here is the exchange of information as well as the discussion of that information, neither of which you contributed in this thread. So without much ado, if anyone is interested in delving a little deeper into lubricity, temperature and various other issues involved with these cars, and you are prepared to do the research, you could do much worse than read the excellent Hartech PDF's on the subject. They are available here: http://www.hartech.org/porsche_996_9...ers_guide.html

all they have to do is go to google and that is all I was trying to say. After spending a decade in the 928 forum, i figured that this place would have the same tech knowledge that was over there. I have never been so wrong in my life judging by the posts that I see here that make me perpetually shake my head and say WTF. It took all of a few seconds to dig up all kinds of info on this subject. http://goo.gl/5ivM1H http://goo.gl/jnqg7I http://goo.gl/qBAHBt http://goo.gl/gUBjI0

The degree of misinformation and misunderstanding about low-temp thermostats on the interweb as a whole is remarkable. I'd guess that at least half of the posts I've read on various forums (be it Porsche, Chevy, Nissan, or whatever) indicate that the poster has absolutely no idea what the low-temp tstat does, nor any idea why they installed it.

Quotes source post: 11821794

What you need, my man, is a Prius.

Quotes source post: 11827210

Additional Hunches from previous episodes: * Hurdi on shafts and holes - er, ignition switches: I have sprayed a little WD40 on the key shaft and into the key hole * Hurdi on debadging: I think that Carrera lettering was put on to stay. That's why I didn't take mine off. Plus why remove the most important lettering of the 911 car. That's like removing the word TURBO to me. Anyway. Bollock already dropped. * Hurdi's pressure-test method for cooling system: If you can lift that pressure relieve valve to the open position and close it by hand without much force, then I take it that the system is working correctly. * And of course, my favorite: Hurdi's "How to be a 1 Percenter:" I am a very flashy person. Wear lots of heavy gold and a classy watch and flash off my 996 whenever I can. I say **** the jealous people of this world. I used to be one of them, until I went out and bought what I really wanted. Do you think I am going to leave my heavy gold, finest watch and Porsche at home. No way. That's why I bought it in the first place. TO FLASH IT OFF. That way I don't have to give anyone the middle finger. My car, Gold and Watch does that for me hahaha. I get more admirers than haters. One blonde girl ran past my car as I was at a junction with the top down. She shouted "Nice car"... I shouted "thanks" and almost followed it up with the words "Nice ***" but that would have only cheapened the moment haha. Dammit, Hurdi, you rock.

Quotes source post: 11830865

He live in PA, are they allowed prius' there, I thought it was a CA disease?

5CHN3LL, that was some of the funniest **** ive read in a long time. That was awesome.