General Maintenance & Repairs - Running Hot??

Hey guys,

As some of you may know I just picked up a 98 T/A M6 a week or so ago. Its been running well, but just today I noticed that it started running kind of hot.

It was about 75 degrees and sunny out today, and after getting off the highway and cruising down a couple back roads, I noticed the temp guage started rising. It went up to 210, then started going back down. Thats the first time its gone that high, the other times I've driven it its stayed at about 180 degrees. It seemed like the car lost some considerable power when the temp went that high as well, and when I drove it later on after it cooled down, it was normal again.

So does anyone know what temperature the stock thermostat is supposed to open at?? 210 seems way too high. And if it is in fact set to go that high, would it be a good idea to switch it out for a 180 degree unit?? I've heard that they can cause problems on some of the newer vehicles though.

I checked my coolant, and it was actually overfull. With the car cool (sat for 30 mins after driving) the dipstick still read above the "HOT" level. The antifreeze also seemed kind of dirty brown, but I think some of that can be contributed to the fact that the Dexcool is orange in color. I'll probably flush and refill the system in the near future just to be on the safe side though.

AFAIK the stock stat opens at ~195*, after a good run on the highway itt's not unusual for the temp to rise a bit, especially if you start going down some twisty back roads with lots of down and up shifting. Highway running you're rolling along with alot of airflow and not alot of RPMs, now you get off and start running harder, it's going to get hotter
FWIW 210 is normal, these cars run hot due to emissions requirements, the 180 is a good temp to go with, not too hot not too cold, but to get the most out of it, it's best to alter your fan turn on temp settings
The dexcool turning brown is a bad sign, get that changed before it turns to brown sludge and completely plugs up your cooling system (don't ask how I know how bad that can be)

Yea 210 is not bad, any higher than that though and you need to start looking at your cooling system for problems. 210 is pretty average for me actually when sitting in traffic.

FWIW 210 is normal, these cars run hot due to emissions requirements,
I always wondered why GM designed these things so damn hot! I never even thought about emissions. I changed my thermostat to 160° and I like it a lot better.

Get rid of that sludge in the dexcool as soon as you get a chance. That stuff can cause nightmares! I run the old fashioned green stuff but I'm supposed to in my LT1. I'm not much of a fan of dexcool anyway.

Thanks for the replys guys. I guess 210 really isn't that high, especially considering its right in the center of the gauge. I drove the car again today, and its the same, stays about 180 most of the time and goes up to 210 in traffic. However, as soon at the needle touches 210, it immediately starts to go back down towards 190, so I think its normal.

I'll change the coolant and maybe swap in a 180 thermostat this weekend, definitely don't want any sludge. I've been using that new Prestone Antifreeze recently, the new one that mixes with all makes/models/colors, and I've had good luck with it, so I think I'll use that to refill the system.

mine stays at 195 all the time...never above never below...

ya, i dont think our factory gauges are too accurate. i put in a 160 stat and dont even see a differnce. the needle sits in the same spot no matter what. lol.

98s are the only ones with a functional temp gauge, after that 99-02 they are basically idiot lights, FYI they did that due to customer complaints about the temp gauge moving too much :eyes:
They will tell you when the car is getting too hot, but other than that they're pretty much worthless as an indication of engine water temp

is it possible to swap to a 98 gauge or is it a big mess? i'd like a guage that actually works.

210 is normal when your fans aren't on and there isn't much air flowing through the radiator ( i.e low speed driving). The fans don't come on until 210 then they stay on until 180 or so. However, if you run your A/C, your fans run on low all of the time. Thats what I do in stop and go driving even when it's nice enough to have the windows down.

210 is normal when your fans aren't on and there isn't much air flowing through the radiator ( i.e low speed driving). The fans don't come on until 210 then they stay on until 180 or so. However, if you run your A/C, your fans run on low all of the time. Thats what I do in stop and go driving even when it's nice enough to have the windows down.

Good to know. I'm going to the dealer tomarrrow to get my speedo/odometer recalibrated for my 4.10 gears, while I'm there I'll also see if they can change the fan settings so they come on at like 190 degrees instead of 210 :)

for some reason mine peak above 210 and didnt seem to come down but it stayed below the 3/4 mark never went any higher.my temp always stayed at 210 before .when i pulled into work the fan was running i checked the fluid lvl and it was fine.if this helps i had to sit in a parking lot of traffic for an hour but ive been in this type of traffic before never had any problem.and its been raining very heavy i did have to go through a 1 foot puddle but the problem didnt start until i was just about at work like an hour after i went through the puddle .how do you adjust the fan setting to come on sooner and should i install a 180 therm