Is THIS too hot?

All three fans (2 radiator, 1 engine) kick on every time I drive. Weather has been in the 70's mostly. Rad fans kick on when temp gauge hits the zombie mark (between 180 and 250), which is usually 5-10 minutes into the drive on suburban roads (no stop-n-go). This is not a new development. Right off the showroom floor it always ran closer to the 225 tick than the 180 tick. Dealer always said "Don't worry about it." My indy says "hey the fans kick on, so not to worry." Oh really now. Shut the car off and those fans stop, so the baking continues. I won't even get into determining the *actual* coolant temp, since Porsche decided that's not something a performance car owner should know beyond an inaccurate dummy gauge. The 6c trick is cool, but why hide it? On my to-do list: find (or build) a guage that displays that 6c digital temp. (including history, like the cpu graph on computers). The hardest decision (sic) will be to get rid of those critical cassette holders to make room for the actual temperature gauge.

Do you consider the temperatures accessable through the climate control unacceptable? A few taps of the right buttons and lots of temperatures are available.

Jon- thanks, I'll try it to see if it stays visible all the time after you do the key sequence, convert from celcius whatever. I've done it once (long time ago), but I just assumed it would be like texting while driving, ie. you'd have to redo the key sequences every time you want to see it.

Just curious why you are tackling all these problems after all this time?

Because it's my only vehicle now, and because I have more time to spend on it.

Gotcha. So just to be clear, you had this issue since you bought it new in '99/'00?

I did the climate control display this weekend. Once I set it up and left it on it stated there even after starting and stopping the car, taking key out, etc. I watched it for a couple days for fun.

Yes, this issue (among others) existed when I bought it new in late '98. The gauge thing started p*ssing me off when friends/family "advisors" would ask "what temp. is it running?", so then me reading the manual and forced to conclude "I don't know WHAT that middle 3/4 mark is, and I'm not even certain those 2 numbers (180, 250) go with those other 2 marks", coz the manual is not clear about that. So now that I've earned my Porsche education (takes a few years), I feel I may want to do something about it, ie. lower thermostat, 3rd rad, etc. Also, the unexpected depreciation hit over the years means I'll be keeping it more years than I otherwise would have.

dg- thanks that's good news.

Clean your radiators

ch- thanks, yes I'll clean the radiators later this week while I'm in there replacing master cylinder. Radiators look spotless, but I guess you have to take them apart, debris gets in between <whatever the sections are called>, per some excellent youtube video I saw.

How old is the water pump, thermostat, coolant and serpentine belt?

All original (25k miles) - water pump, thermostat, coolant and serpentine belt.

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Time for all to be replaced.

Get yourself a $20 Harbor Freight IR thermometer and take some readings to verify the data you get from the car.

Based on my experience over the years and by observing the coolant temperature it takes considerable driving after a cold start before the engine is hot enough to cause the radiator fans to come on. It takes stop and go driving, with idling mixed in, before this happens. For instance I can drive 30 freeway miles -- to work -- and only after I have been sitting in a fast food drive in driveway for a few minutes do I see the temperature gage (or the actual temperature) climb to the point that I hear the fans come on. If the A/C is not on the fans coming on that soon after cold engine start suggests there's a problem with the fan electrical system or possibly (maybe this should have been first) a problem with the coolant temperature gage. Do you know the coolant temperature at the time the fans come on? As you are aware of I think you can use the A/C display to display the coolant temperature. Or you can get an OBD2 code reader/data viewer and through the OBD2 port read and display coolant temperature in real time. If you observe the coolant temperature rising to 212F (the temperature at which I have observed the fans come on in my Boxster) after a cold engine start in just a few minutes that's a sign the cooling system is not working properly. I would suspect a T-stat or water pump. You can if you want check T-stat and water pump operation by starting a cold engine with the car on a lift and carefully (!!!) checking the temperature -- by feel -- of the hoses to/from the water pump housing to confirm that as the coolant in the engine warms up it flows to and from the radiators. If you observe the fans coming on before the coolant temperature reaches 212F that's a sign the fan electrical system possibly has a problem. (Or the DME fan stage controller system is bad.)

Schnell- thx IR therm. will confirm temp. readings. Macster- thank you for taking the trouble to write that up, stepwise and methodical works well for me. Thermostat seems to open at approp. time, and coolant seems to be circulating thru radiators, based on temp. gauge. Temp slowly climbs to 180 marker, then stops rising for a couple minutes (circulation!), then another slow creep up into the zero (in 180), where it stays for another couple minutes, then I start having fun (2nd gear, 3rd gears runs up into 4-5k rpm), then temp rises to 3/4 mark and fans kick on, and that's how it stays for the rest of the drive (30+ minutes). I'll perform your tests as the days progress this week.

So yeah I'm gonna flush the coolant (dealer) and go from there. Before that I'm gonna measure the pH just for my curiousity. And clean the radiators, and the other diagnostic/maint stuff. I think the coolant system is working, just not as well as it could be. I think it's a maint issue, not a structural issue. I'll update the results, that's how I roll.

Replace your water pump and thermostat since you're in there. It's not a matter if the pump will fail, just a matter of when. You're overdue.

Can someone clue me in to how to check actual engine temp through AC? Is this in the owners manual? Thanks, Paul

Press and hold in the recirculate and the top (arrow up) buttons on the right side of the panel for a few seconds. The left screen will change. Using the + key below that screen, advance so the display reads 6c. Then press the center vent button once. The display will show you your coolant temp. To revert to the original HVAC settings, just press 'auto'. For the rest of that drive cycle, you can get the temp info again by pressing the recirc and arrow up buttons again, and the temp will appear immediately. You have to repeat the whole process for the next drive cycle.

https://rennlist.com/forums/6995148-post43.html

Thanx Guys!

For reference, HVAC showed my car running at 94c (201f) @ 70mph, 4th gear, 23.8 degrees c (75f) ambient temperature. At 94c, the needle on my dash is vertical. Readings with an IR gun were consistent with the HVAC's indicated temp. My car may run slightly cooler than others, as it has been equipped with 3rd radiator.

This weekend I went through rain and sun. Temps from 67-82F. Stopped traffic and on highway. Temps were between 93 - 98C. I got the 98C on hot day. Not in traffic, but on a hot day on back roads driving the kids around with a lot of start/stop. 98C was almost at the far egde of the 0. Only 2 radiators, but low temp thermostat. As a question, I have seen some say the low temp thermostat will lower the operating temp, but I just thought it opened sooner, so at operating temp it should be wide open with either thermostat so final operating temp should be the same?

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I was thinking about the same thing this weekend...there is a lot of misinformation and misunderstanding about the function of a low-temp thermostat. Once the tstat is open, temperature is dependent on heat in (engine) vs. heat out (radiators) - the tstat can't affect this outcome. The low temp tstat adjusts the floor, rather than the ceiling, of the cooling system, so things do not have to be as hot to engage the full capacity of the cooling system. It has no effect on top end temperature.

Check your outside engine temp probe to see if it didn't fall out of place. Only had my car for roughly a month thought it was strange that my rear fan on the motor would be running all the time and for a long time after shutting down. After being stuck on the interstate in bumper to bumper traffic in 100 plus outside temps my engine compartment temp warning light came on when the temp gauge was reading below 200. When I finally made it home decided to investigate why it went off sure enough found the probe laying on the motor. Now my rear fan didn't even turn on after shutting down when I came home today in 90 plus temps.

@dgjks- yes the digital engine temp. display stayed on just as you said, bingo there's my new gauge, way cool. @dgjks, @schnell- good point re: low temp. thermostat, so I can cross that off my list. Here's some temp. readings and observations from my little test circuit run this morning, mostly suburban housing development, so speeds of 25-45 mph, weather temp. 80 F. Celsius (F), because I couldn't get the conversion keystrokes to work. 81 (178 F) - center mark on gauge, so that mark is accurate. 91 (195 F) - 1st stop (pause) in rising process, paused here a few minutes. 101 (214 F) - middle of zero in 180. 108 (226 F) - fans kicked on (all 3), temp. stayed here idling, end of test. 110 (230 F) - max temp. driving around town recent weeks. Just left of 3/4 tick mark, which I thought was supposed to be 50-percent between 180 and 250, which would be 215, so seems a discrepancy there. Also makes me think if 3/4 tick is 230 (F), then 250 tick might be 280+ which would not be good. Conclusion - current 230 (F) max temp. not too bad right? and I'll be improving that in coming weeks.

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Don't be so quick to discount the low temperature thermostat. http://911uk.com/viewtopic.php?t=94337

A low-temp t-stat may still be worth installing, since it starts the coolant flowing through the radiators at a lower temp. On many cars, the low-temp thermostat can be more of a hindrance than a help, since it prevents the engine from reaching operating temp as designed by the manufacturer. For the M96 that (apparently) has some hot spots due to how the coolant flows through the block, starting the flow of coolant to the radiators may help prevent localized hotspots. To my knowledge there is little empirical data (localized temperature readings, thermographic imagery) that definitively proves that the M96 should always run a low-temp tstat, but there are plenty of reputable (in my opinion) resources indicating the use of one on the 996 may be a good idea. If your thermostat is not functioning properly, it can definitely lead to the car running hotter than it should. If this is the case, a new thermostat, regardless of whether it's a low-temp thermostat or the OEM thermostat, is advisable. However, much of the Interweb's reasoning for running a low-temp thermostat is hopelessly flawed, which is what posts 25 and 26 in this thread address.

There are pros and cons but if your car is genuinely running hot during normal operation then an LTT will assist it in running cooler, however a car running hot under normal conditions is doing so for a reason which probably warrants further investigation.

One additional thermostat comment - and then I'll shut up - is that neither thermostat (OEM and low-temp) is binary - i.e. they don't go from 0% open to 100% open instantly. I point this out only because it can help make sense of the numbers if you're fixated on operating temp and trying to figure out why things happen when they happen.

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If the radiator fans didn't come on until the coolant temperature reached 226F that's a problem. (Not the 226F but the fans not coming on before then.) My info is the fans should have come on low speed way before 226F (by my observation they come on at 212F) and should have been at high speed if the coolant temperature climbed to 216F (again by my observation). Based on what you posted I believe you need to investigate a possible problem with the fan electrical system stages of the ECU/DME with a bad T-stat or water pump also possible. (There are always 2 problems, unless there is just one or 3 or more problems...) If the car's cooling system is correct there should be no reason to install a low temperature T-stat or make any other changes. The car's cooling system, as it comes from the factory provided everything is ok should keep the engine reasonably cool -- though under some high ambient temperature conditions or on milder days with severe, err spirited usage the coolant temperature might climb to 226F (my observation more than once) and in high ambient temperature stay there but the engine will suffer no harm. If the temperature reaches 226F on a milder day but during spirited usage as soon as the spirited usage stops the coolant temperature should drop and when it reaches 205F (my observation) the fans should turn off.

Don't know if this will help, but I have no idea when my front fans kick on, but my rear fan kicks on at 95C. And my car has not crossed 100C yet.

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Right on Macster. Low speed mode is not working, per my ears. Also, passenger side fan is not working, per me walking around it and kneeling down and listening.

Can I run without A/C condensers? I don't use A/C anyway. I figure removing those condensers would increase airflow to the radiators, until such time as I can diagnose the fan problems. I removed the bumper etc. and will be cleaning the rads today. They're a little dirty but not too bad. Compressed air's not gonna cut it, coz it's more like caked on dust/dirt. So I'm gonna use soap and water and a brush. Hope the brush doesn't damage anything. Rads are pretty cheap, maybe just buy new ones? Dealer appt. Monday for coolant flush and general look-see. I was gonna just drain/fill myself, but want to ensure it gets pressurized correctly, no air pockets etc., and I don't have the tools and it would be my first one.

Fixing the cooling fans should give you big improvements from where you are now. Next stop will be the water pump and thermostat.

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Probably not a good idea to disable the AC system. Even if you don't use it for cooling, I believe most vehicle AC systems assist in keeping your windshield clear of fog when the defroster is on - and you never know when you'll need it. Case in point, I had an old 2 seater without AC. Had friends over for the evening and a buddy and I were sent out to pick up pizzas for the whole crew. On the way home, my buddy carried the 8 steaming hot pizzas on his lap in the passenger seat. As soon as we pulled out onto the street, the pizzas fogged up the entire windshield - holy crap, it's nighttime on a busy street and all I can see is a wall of fog - no AC available to quick clear the windshield.

The 996 also uses the AC to cool the fuel - one more reason to leave it in place.

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Um, are you sure? I think only 996 turbos have it.

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+1 With the 996 cooling system it's the "sum of the parts" that make the difference. When I bought my car with 86K miles on it all those things were original. New WP, coolant, belt and cleaning the rads made a substantial difference in lowering the peak temp. I've also put a low temp Tstat in as well and while it won't stop your car from hitting peak temps it does run cooler a lot of the time and allows the car to warm up a little quicker.

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Per The Essential Companion, "a fuel cooler is installed in the engine bay in all US market 3.4 L 996 models and all 3.6 L turbocharged models worldwide." This applies to OP's car (and mine)...

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That is interesting. I've only seen it on 996 turbos (photo in the link below) but not on the 3.4 . Maybe someone has a pic of it on the 3.4? http://www.autoatlanta.com/porsche-p...section=813-26 https://rennlist.com/forums/10549141-post8.html

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You'd better go back to T-stat class. A lower temp T-stat opens at a lower temperature but the engine will take longer to warm up to its nominal operating temperature. It will be interesting to see how engines that have been fitted with a low temp T-stat fare over time after having to deal with colder and thus thicker oil and oil that because it is colder can't shed the build up of unburned fuel and water.

...especially since many of us are using incrementally more viscous oil than the factory fill...

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I don't think this will have a big effect unless you are concerned with .00025 hp. The only guys I know that uses a fuel cooler are straight line guys at the tracks.

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Not when it's normal operating temp is what 20 degrees colder then with the stock T-stat due to the low temp T-stat. Technically you're right though because the normal operating temp is so much higher stock. My car is pretty much an occasional good weather only / drive to the track / track car at this point so I'm not worried about unburned fuel/water. My current OAs would support that unburned fuel/water in not a problem with my motor. Someone in colder climates who isn't running their car hard or for longer distances might be better served without it for the reasons you point out above.

I've diagnosed the right side fan problem as a dirty relay bank. So the solution for that is electrical contact cleaner, per autoatlanta.com. So would Autozone be okay for electrical cleaner? Bcoz now I'm in a hurry before Monday dealer appt. (coolant flush), so I wanna factor out the relay socket so they can test the fan. Thanks. How I got there: 1. Cleaned radiators. 1.5 Baseline- left side fan works both hi and lo, right side fan fails both hi and lo. 2. Swapped the relays left side <=> right side. Now test. 3. Low speed works on both sides. 4. High speed works on left side, but not on right side. Conclusions: 5. The right side hi socket is the dirtiest (and dirtier than its relay). 6. All relays are good, bcoz the suspect rightside relays work after swap to leftside. 7. Rightside low speed fixed by reseating relay. 8. Both rightside sockets were difficult to pull out of, difficult to put back into, and felt a little gritty and small amount of staining (rust colored). 9. The sockets are dirtier than the relays. Which is why I want to clean the sockets (bank).

Did you swap the high speed relays between the two sides and confirm the right side fan high speed indeed works with a good relay? I would suggest a new relay unless you can open it up and clean the contacts inside.

Seems like you're well down the path. If you've got all low-speed fans; getting to the high-speed for both shouldn't be a frequent occurrence unless you're in a really warm environ. One piece of mind option as a short-term fix while you get a new relay (if not immediately available) would be to add an over-ride switch to force high-speed fan on. In my race car I have the standard temp-driven relays and then manual over-rides for each fan-speed. Don't take out that A/C - and actually just turn it on. Then you have drawn-air vs. forced-air through the radiator cores all the time. That should improve things a lot. The way I think of it is: a. A/C triggers low-speed rad-fans = pretty much on all time b. ECU triggers Med / 1st real fan should be after thermostat is wide-open and coolant temp is nearing 100c c. ECU triggers High-speed / 2nd-speed for over-temp prevention Enjoy the fruits of having the snowflake button pressed for a drive and see if anything is better

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I'm not sure what you mean by "Med" in (b). I'm only aware of low and high. Is there a medium?

Just to pay it forward for future searchers ... "Too hot" = 230+ (F) for any length of time. You never want to hit 250-260. Warning lights come on at max tick (280F) and damage is definitely being done. Gauge marks are 180, 250, 280. Hi speed fans come on at 226F (108C). If they don't immediately start lowering temps (back to 210-) then you have a problem. This is from the dealer today.

Sorry. Brain fart. Deleted original text to minimize confusion on an already confused site.

I would argue that is entirely wrong. The fans draw cool air in from the front and expel backwards. If your fans are running backwards then you have a problem. If you think about it, that makes no sense whatsoever. It is right that the AC condenser is in front, then the radiator.