OT: cooling question

[joeb]

the people here seem pretty sharp on car issues. i have a grand prix GTP that runs hot during stop and go driving. i have a 180 degree thermostat but the temp gauge indicates 210 during stop and go driving. on the highway the temp gauge drops way down. i have an aftermarket chip and the fans run almost all the time. coolant level is fine. turning off the a/c makes no difference. does this look like a WP issue or perhaps plugged radiator? maybe i have a funky temp gauge or sender? i did have a 195 thermo earlier this spring and it ran hot than. the lower temp thermo made no difference.

[Ranger]

Don't know too much about that car, but I would bet that 210 is normal running tempurature.

[BodybyFisher]

the people here seem pretty sharp on car issues. i have a grand prix GTP that runs hot during stop and go driving. i have a 180 degree thermostat but the temp gauge indicates 210 during stop and go driving. on the highway the temp gauge drops way down. i have an aftermarket chip and the fans run almost all the time. coolant level is fine. turning off the a/c makes no difference. does this look like a WP issue or perhaps plugged radiator? maybe i have a funky temp gauge or sender? i did have a 195 thermo earlier this spring and it ran hot than. the lower temp thermo made no difference.

Is this the 3100 or 3400 engine? What year is this car? As Ranger stated 210 in stop and go is not alarming...

[JasonA]

JoeB, do your cooling fans run all the time on HIGH or on LOW? If low, it's likely still not going to always be sufficient enough to maintain a low coolant temperature, just as ours aren't, on low. But that's okay -- because our fans (and yours as well probably) will switch to HIGH when the coolant temperture REALLY gets warm, like in the 230-235 range.

If your aftermarket chip locks the fans on HIGH all the time, and it's still creeping up, THEN you might have an issue. My brother's '99 C5 has a Magnusson-Lingenfelter supercharger and the reprogramming keeps the fans on HIGH all the time. No matter what you do, no matter where you are, and no matter the outside temperature, the engine is a ROCK SOLID 180-185. In traffic, on the road, doesn't matter.

But yours sounds like an airflow "problem". But again, I don't really think it's a problem, because the fans will go higher if they need to when the engine warms up. Our Northstars have 195*F thermostats, but in traffic it's common to run 205, 210, 215. The airflow through the radiator with the fans on low speed just isn't enough to keep the temperatures down.

[joeb]

it has the buick 3800 motor with the supercharger. during cool weather, which is sept-june in MN, the temp gague usually stays around 180 or so. it seems to hover around the thermostat temp. but as soon as summer gets here, the temp gauge goes up. its my sons car so i only drive it occasionaly.

[BodybyFisher]

I was just checking as the 3100 and 3400 engines have problems with their intake manifold gaskets where coolant can get into the crackcase. I don't thing the 3800 has that problem. The next time you change your oil put it in a clear container and let it sit..... if it separates its an indication that coolant is present...I have done the gaskets on a 3100 and need to do my wifes 3400 Monte Carlo...

However:

1) you didn't indicate you are loosing coolant

2) your temps don't seem bad

You say 'runs hot at" 210 degrees, but you say that is that 210 degree temp in stop and go, what is your temp at 60 with no traffic? My NS will run 222 to 233 in traffic, while simultaneously raising my blood pressure 20 points. You seem to be OK..

[Ranger]

BBF,

Not sure about the S/C 3800's, but the N/A 3800's are known for the EGR "stove pipe" heating the manifold, making it brittle and in some cases, actually burning through them, thus injesting coolant. When I R & R'd my wifes, I made a modified, necked down "stove pipe" so it no longer was in contact with the manifold.

They are also known to leak around the T/B mount. That's where mine was leaking.

[BodybyFisher]

BBF,

Not sure about the S/C 3800's, but the N/A 3800's are known for the EGR "stove pipe" heating the manifold, making it brittle and in some cases, actually burning through then, thus injesting coolant. When I R & R'd my wifes, I made a modified, necked down "stove pipe" so it no longer was in contact with the manifold.

They are also known to leak around the T/B mount. That's where mine was leaking.

Interesting and good to know about the 3800. It's possible the S/C version has the same limitations although the intake design might be different.

[joeb]

i visit a GP website and the topic of running hot seems to be fairly common. changing the WP is a PITA so i don't want to go there. We got the car last yr with a 180 thermostat. I changed it this winter for a 195 which is stock for a little extra heat and it took a few days of driving to get most of the air out of the system. the temp gauge would stay around 160-175 and slowly creep up to 215 and than drop down to 180 or so. i have a tranny temp gauge and it usually stays around 150. we had some hot weather in late may and driving in stop-n-go traffic the coolant gauge went up to 215 or so and i looked at the tranny temp gauge and it was over 210.

[JasonA]

I bet the topic of running "hot" is as common on other sites as it is on ours, especially with cars with electric cooling fans on which you can read the actual coolant temperature. It will vary widely depending on the type of driving. Our old RWD vehicles with mechanical fans were much more stable -- but it also took horsepower to run.

This is precisely why the coolant temperature gauge is "damped" on the Cadillac -- it runs "straight up" for all normal coolant temperatures...as low as 190 and as high as 220. Anything in between is a-okay. I'd say the same for the 3800 engines. 215 in stop-n-go traffic in warm weather is completely normal. We perceive that as "hot" because the car might normally run at 190 or 200, but it's really not that warm.

Again, it's an airflow issue. You *could* run the cooling fans at high speed all the time, and that would likely solve the issue. It would not be necessary, and would draw more amps, but your coolant temperature would likely be much more steady.

Personally, I wouldn't mind trying it to give the A/C a "boost" in traffic -- because you'd get more airflow across the condensor. But don't do it for the coolant temperatures because even at 215, that's totally normal.

[joeb]

my GP is a 97. a friend has the same model but its a 2001. his temp gauge seems to stay at 195 as it should and in traffic it will go up to 205 or so but as soon as he gets rolling, it will come down to 195. they say if your car is running hot, a thermo will not "cool" it. once the thermo opens, the conditions will keep the engine temp above the thermo opening point. so if a WP is bad, or radiator is plugged or whatever, the engine will run hot. if i take out my thermostat and drive in similiar conditions, it should still run "warm".

[JasonA]

...they say if your car is running hot, a thermo will not "cool" it. once the thermo opens, the conditions will keep the engine temp above the thermo opening point...

That's partially correct. Depending on the application, the rated temperature for a thermostat is the temperature at which it BEGINS to open. The FSM for my '84 Cutlass stated the thermostat should BEGIN to open at 195 degrees, and become fully open by 210 degrees, or something close. If the engine is running warmer than the full-open temperature of the thermostat, then yes, there is another reason, and a cooler thermostat will likely not cool it down.

There is some variability in thermostats. The OE thermostat on my '97 kept the engine around 197-201 most of the time. The ACDelco thermostat I installed when I did my water pump runs the engine in the 190-194 range most of the time. Same exact thermostat, just at different ends of the "tolerance scale" I think.