overheating problem

[barrelrcrdad]

Hi. I'm new here, but I read everything on here religiously. I just had a new LS7 clutch installed and while they were at it, I aked them to check for any problem with the cooling system. A new 160 deg thermostat was installed and the fans were set to come on at lower temp. New Dexcool was added. When I drove off, and by the time I got about twenty miles out, the temp gage was at about 240. Went back and they said that because the air dam was missing, that could cause the problem. Installed a new dam. Now it runs at about 190 if the outside temp is around 90 or hotter. As long as I am running at a steady speed, everything is ok, but as soon as the rpm goes up, the temp starts to climb. When I slow down for traffic and start shifting, the temps climb. So far it only gets to about 208, but should the temp go up just because the rpm is over 2000? When I am on cruise at 70 and accellerate to pass, the temp climbs a few degrees. Is this normal? Thanks

[froggy47]

Everything I have read says the air dam is a very important part of the cooling system.

Going up to 240 because it's missing seems a lot though.

The temps you are looking at now, with those mods you made (stat & fans) seem normal to me.

If you don't mind, why was it missing?

:)

[LLC5]

Originally Posted by barrelrcrdad

Hi. I'm new here, but I read everything on here religiously. I just had a new LS7 clutch installed and while they were at it, I aked them to check for any problem with the cooling system. A new 160 deg thermostat was installed and the fans were set to come on at lower temp. New Dexcool was added. When I drove off, and by the time I got about twenty miles out, the temp gage was at about 240. Went back and they said that because the air dam was missing, that could cause the problem. Installed a new dam. Now it runs at about 190 if the outside temp is around 90 or hotter. As long as I am running at a steady speed, everything is ok, but as soon as the rpm goes up, the temp starts to climb. When I slow down for traffic and start shifting, the temps climb. So far it only gets to about 208, but should the temp go up just because the rpm is over 2000? When I am on cruise at 70 and accellerate to pass, the temp climbs a few degrees. Is this normal? Thanks

Your temps are normal, these engines are designed to run into the 220-230 range. I would consider removing the 160*F t-stat though. Good luck with it.

[barrelrcrdad]

Thanks for the quick reply. The dam was missing when I purchased the car. It is an 02 Z06, and even with a little over 100 thousand on it, and with only a callaway honker intake and an aftermarketcat back exhaust, (unknown) when I had it tuned, it gave me 367.1 hp and 349.4 torque. Why should I lose the 160 thermostat?

[LLC5]

Originally Posted by barrelrcrdad

Thanks for the quick reply. The dam was missing when I purchased the car. It is an 02 Z06, and even with a little over 100 thousand on it, and with only a callaway honker intake and an aftermarketcat back exhaust, (unknown) when I had it tuned, it gave me 367.1 hp and 349.4 torque. Why should I lose the 160 thermostat?

The LS engines are designed to run in the 200F range for maximim efficiency, power, and most importantly reliability. 160F t-stats should be used with an engine specifically designed to run at that temp.

[froggy47]

Originally Posted by barrelrcrdad

Thanks for the quick reply. The dam was missing when I purchased the car. It is an 02 Z06, and even with a little over 100 thousand on it, and with only a callaway honker intake and an aftermarketcat back exhaust, (unknown) when I had it tuned, it gave me 367.1 hp and 349.4 torque. Why should I lose the 160 thermostat?

I run a 160 & fan mod and my operating temps are never less than 195 (ez cruze) to 230 ish (hammer down on track). My opinion fwiw is if you live in a warm/hot part of the country the 160 & fan mod is good for the engine, if you live in Fargo maybe not. I know this is not according to GM, but there it is.

GM also calls for a longer oil change interval than Froggy does. So we differ on a few points.

Enjoy the car & drive it fast & safe.

:)

[c4c5specialist]

HI there,

Another reason for the stock Tstat is because of thermal expansion of the piston to bore clearances.

Allthebest, c4c5

[LLC5]

Originally Posted by froggy47

I run a 160 & fan mod and my operating temps are never less than 195 (ez cruze) to 230 ish (hammer down on track). My opinion fwiw is if you live in a warm/hot part of the country the 160 & fan mod is good for the engine, if you live in Fargo maybe not. I know this is not according to GM, but there it is.

GM also calls for a longer oil change interval than Froggy does. So we differ on a few points.

Enjoy the car & drive it fast & safe.

:)

If you are running at 195-230, which is actually perfect, then I would say that you are not see the "benefits" of a 160 t-stat (which is actually good thing for these engines). If ambient temps are low enough and the cooling system is working properly, then you could be running at 160F which is not good for an LS engine. Paul hit the nail on the head with thermal expansion rates and durability issues.

I am with you on the oil change intervals, no 10-15,000 mile oil changes for me either. I am sure that you can go that far fairly safely if you drive easy, but I am not going to take that chance myself.

[barrelrcrdad]

Thanks a lot guys. I will change the thermostat back as soon as possible. I also change my oil a lot more often that required. This is the best forum going

[froggy47]

Originally Posted by LLC5

If you are running at 195-230, which is actually perfect, then I would say that you are not see the "benefits" of a 160 t-stat (which is actually good thing for these engines). If ambient temps are low enough and the cooling system is working properly, then you could be running at 160F which is not good for an LS engine. Paul hit the nail on the head with thermal expansion rates and durability issues.

I am with you on the oil change intervals, no 10-15,000 mile oil changes for me either. I am sure that you can go that far fairly safely if you drive easy, but I am not going to take that chance myself.

I think we basically agree, I monitor my oil pressure & oil/water temps like all the time. The low temp stat just opens a little earlier than the factory stat, once they are both open & engine temp is climbing I don't see as there is a nickel worth of difference. Fan temps are another thing altogether. Especially since our cooling system picks up debris like a hoover.

When you autox, you want the temps at the low end of "normal" to avoid pulling timing, once you are into a 60 sec run the temp will climb, so you do NOT want to start the run at the high end & have the cooling system fighting the whole time to pull the temp down. Hence the 160 stat.


I would not run a 160 in the winter in a cold climate, for the record.

:)