LS1 - overheating

**kris** · 06-14-2014, 01:04 PM

Hi,

I need some expert advice regarding my overheating problem. The engine is a bone stock 2002 Camaro Z28 engine.

Diagnosis so far using a pressure gauge on my cooling system and HP-Tuners revealed the following results:

If I let the car idle for a long time (approx 60. min) it will reach a terminal temperature of 116c and 23 PSI.
After turning the cabin heater on for a while it will drop to 97c and 11psi.
It does not smoke white, mix oil/coolant or use a noticeable amount of coolant.
When I go WOT a couple of times the temperature rises quickly and it needs a long time to cool down to normal running temperature again.

Any ideas on what could be wrong?

Head gasket?
Air in the cooling system?
Crack in head or block?

Help would be greatly appreciated before I tear it down!

**2002ssslp** · 06-15-2014, 05:44 AM

Pull the radiator and see is the cooling fins are clogged. If they are use a hose to clean the area and also check and replace your hoses and coolant if needed. Airflow is key to keeping your cars cool.

**Firebirdjones** · 06-15-2014, 06:37 AM

You didn't mention it so I have to ask...

Are your fans coming on?

**pajeff02** · 06-15-2014, 07:54 AM

Has the cooling system ever been serviced? If not, it is likely gunked up as the service interval is around 5 years. These cars come factory equipped with GM Dexcool and shouldn't be mixed with any kind of "green" coolant no matter what it says on the bottle. Your best bet is to pick up a laser temp gun (around $35 to $50 here in the U.S.) to check temps. The factory thermostat is fairly hot, but should be fully open by around 198 to 200 degrees (F).

With the engine cold (and taking car not to get snarled up in the belts or fans) start the engine. As the engine warms up you should be able to feel the upper radiator hose start to get warm. By the time your gauge reaches the thermostat's rated temperature the upper hose should be fully hot. Use the laser to verify your temperature at the thermostat housing, the lower hose outlet and on the hoses. If the temp keeps climbing and your top hose stays cold, there is an issue with the thermostat. If the top hose only warms up, but the temp on it doesn't come up like it should, your radiator core could be plugging up and cutting down on circulation.

**0rion** · 06-18-2014, 06:04 AM

116c = 240f for those of you following along in the book.

Sounds to me like you're not cooling optimally but I also don't think you have a problem there. Your second fan isn't programmed to come on until 234F or 112c so you're only a few degrees off. T-stat opens at 195f (90c) so ideally you'd want that temp to stay right around there. Has the coolant ever been changed? If not it's way past due. You could also clean the radiator out like 2002ssslp suggested. If you take the air deflector and what not off the front you'll probably find quite a bit of trash in there. What's your temp look like going down the road? An idling car would be the hardest to keep cool because of the lack of airflow through the radiator. An hour is a long ass time to let a car idle. Clean the radiator and put new dexcool in and I bet you'll see better temps but I'm not sure I would expect 195(90) after letting it idle for an hour. Things get hot and hold heat and it's tough for just the fans to control that temp without running balls out.

**jfl330** · 06-20-2014, 04:25 PM

Never used HP-Tuners, but see if you confirm what temperature the fans are set to come at. Perhaps while playing around with hp-tuners, the fans temps got raised instead of lowered that most people do.

And as someone else asked, be sure both fans are indeed coming on.

When I got my car, it had a cooling issue, turned out to be a few plastic bags got sucked up into the fans and blocked the air flow.

As already said, air flow is essential.

**kris** · 07-12-2014, 09:18 PM

I took a block tester and it was inconclusive - it changed color but never got solid yellow.

Would a leak down test give me a definitive answer for a leaking head gasket?

**pajeff02** · 07-13-2014, 03:52 AM

Has the cooling system ever been serviced and were you able to verify that both fans are operating?

**kris** · 07-13-2014, 10:16 AM

Originally Posted by pajeff02

Has the cooling system ever been serviced and were you able to verify that both fans are operating?

Yes and yes

**pajeff02** · 07-13-2014, 03:39 PM

The cooling system on our cars does like to airlock if the coolant level drops or after servicing the system or replacing the thermostat. The temp gauge in the dash is a POS right from the factory -- do not reply on it for accurate readings. Use either a scanner or a laser temp gun to verify coolant temps. The stock thermostat is right around 195 to 198 degrees F, so temps of 210 to 215 are not uncommon under load on a hot day. Most owners swap out for a cooler thermostat and reprogram the fans accordingly.

**kris** · 07-18-2014, 11:17 AM

Took another block test as the first one was inconclusive - would you say this one is conclusive?

For this test I held the engine at 3000 rpm and the results below appeared in about 15-30 seconds.

This happend when I tried to bleed the system a last time - doesn't look right or?

**pajeff02** · 07-19-2014, 03:43 AM

Unless it was purging air trapped in the cooling system, I agree that does not look good. Did you pressure check the cooling system? Not sure what you mean by "block test".

**kris** · 07-19-2014, 03:15 PM

Originally Posted by kris

Took another block test as the first one was inconclusive - would you say this one is conclusive?

For this test I held the engine at 3000 rpm and the results below appeared in about 15-30 seconds.

This happend when I tried to bleed the system a last time - doesn't look right or?

I had some trouble with the picture - it is fixed now.

**kris** · 07-19-2014, 05:38 PM

Tore it all down today - I just looked over the head gaskets and heads quickly and they both seemed ok.

Maybe I need to split the MLS head gaskets apart to find the leaks?

Found this in cylinder 8 though:

Seems like this engine has blown a gasket before and someone let the coolant sit there too long so the wall got heavily pitted or could there be a crack in the block?

All the other cylinders were spotless.

**kris** · 07-19-2014, 06:11 PM

This engine came from a reputable seller on Ebay and were supposed to have done only 71k miles.

After this experience I am not sure that I want to take the chance with another used engine again. I could rebuild the one I have but I would also like to save some time.

Are new LS1 crates still available?

What about remanufactured units like this: Remanufactured 5 7 Long Block 1 Year Unlimited Mileage Warranty LS1 Aluminum | eBay ?

**pajeff02** · 07-20-2014, 02:52 AM

Yikes! That doesn't look good.

If I recall, you can perform a cleanup of no more than .010" on a stock LS1 as it is a sleeved aluminum engine block style engine. A machine shop should be able determine if that would be sufficient to fix the damage. There are many reputable sellers of both long and short block LS1's. I have not heard of the one you linked in your post however.

**kris** · 07-20-2014, 03:02 AM

Who would you recommend?

**pajeff02** · 07-20-2014, 03:35 AM

I have no direct experience with any seller, but would not hesitate to buy one from Mast Motorsports, Golen Engine Service, Livernois Motorsports, or GM Performance Parts.

**kris** · 07-20-2014, 03:37 AM

Originally Posted by pajeff02

I have no direct experience with any seller, but would not hesitate to buy one from Mast Motorsports, Golen Engine Service, Livernois Motorsports, or GM Performance Parts.

Thanks, I will check them out!

***SMWS6TA*** · 07-22-2014, 12:52 PM

Originally Posted by kris

This engine came from a reputable seller on Ebay and were supposed to have done only 71k miles.

After this experience I am not sure that I want to take the chance with another used engine again. I could rebuild the one I have but I would also like to save some time.

Are new LS1 crates still available?

What about remanufactured units like this: Remanufactured 5 7 Long Block 1 Year Unlimited Mileage Warranty LS1 Aluminum | eBay ?

Don't forget about LQ4 or 9's You can get them a hell of a lot cheaper and have better upgrade potential and options