kristov

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 241 F and 23 PSI.
  
• After turning the cabin heater on for a while it will drop to 207 F 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?

1. Head gasket?
   
2. Air in the cooling system?
   
3. Crack in head or block?

Help would be greatly appreciated before I tear it down!

JRENIGAR

iTrader: (37)

Could be a slight blockage in the cooling system. Maybe it flows enough to keep temps in check when just crusing but when a hard load is put on the engine the cooling system cant keep up. WOT is where the engine makes the most power and power is heat. Try flushing out the coolant in the system for 100% water and see if it helps any. I believe water cools better than antifreeze but I might be wrong.

Fry_

Convert that Celsius crap to Fahrenheit most people on this site live in America, and have a mod move this to the maintenance and repair section. Your also over thinking the problem, there is no way your cooling system is going to hold 23 psi if you have a bad head gasket or cracked block or head. Because it cools off with the heat on makes me think it's a air flow problem, check between you ac condenser and radiator, it's not uncommon for it to get packed full of gunk. Also make sure the air damn isn't missing.

kristov

Thanks, everything in the coolingsystem is new so i think that should be ok.

What do you think of the high system pressure in the cooling system?

Is 23 psi normal?

kristov

It now says Fahreheit

23psi was with the pressure gauge. With the stock 18 psi radiator cap it boils over when doing a couple of WOT's and then letting it idle.

Red89GTA

in the same idea as a blocked cooling system, a thermostat that isn't fully opening will have the same effect. If you decide to take it out, remember the temp rating is when they start to open, not when they are fully opened.

As far as water cooling better than antifreeze, yes technically true. However, you will need an additive like water wetter to reduce the water's surface tension (helps against steam pockets) and provide lubrication for the water pump, you don't want to kill that for no reason.

6t7gto

iTrader: (1)

As was mentioned, check for dirt between the a/c condensor and radiator. I pulled a drive train from a 2001 Tahoe and the radiator was plugged almost solid with dirt.

Fry_

Had the same problem with my GF's Grand Am 11yr's ago I was only 18 and I figured out what her dad and his mechanic couldn't. This was after I put the thermostat back in because he wouldn't believe taking it out would make it over heat faster.

Paul Bell

iTrader: (9)

Is that right? New water pump, radiator, thermostat?

Is there dirt clogging the condenser? This will reduce air flowing through the radiator.

Does the high temperatures occur on the highway or standing still? Is the lower airdam in place?

Do the fans run when they're supposed to?

joecar

Did you burp the air out via the steam crossover tube/hose...?

Adam123

iTrader: (1)

Have you had the heads off? If so, what HG did you use? Have you shut the engine off while hot and radiator is pressurized? Sometimes a HG can blow and while hot water will come out from between the HG and Head.
Heater core new or old?

Goodkat

iTrader: (2)

Take a long air gun and blow out the condenser if that doesn't work change thermostat easiest and cheapest way to go about this issue. Besides flushing the system

Carguy8888

iTrader: (1)

In for info.

spy2520

iTrader: (3)

Cooling fans working?

fsvaasam

Hi guys, my first post here! You say your engine is a bone stock 2002 Camaro Z28 engine but is it in its original body? I have LS1+ 4L60E in a 3gen nova and i had from first start terrible airlock problems in a heater core. I made bleeder routings like F-bodys have and problem was solved.

.boB

iTrader: (1)

I thnk this is the key point here. A rise in pressure usually means that combustion gasses are entering cooling system. specially if it rapidly occurs after a short WOT run.

You can by a kit the will test the coolant for by products of combustion. If that test is positive, you most likely have a head gasket problem.

Another clue would be the needle fluctuating or bouncing at idle when the pressure is high.

kristov

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?

Red89GTA

Possibly, make sure the engine is warmed up, pull all the plugs (so you car hear any cylinder to cylinder leakage), then each cylinder in turn, make sure to have at tdc when you pressurize it. Have the rad cap off and check for bubbles, or even some sort of flow. That will show you if air is getting into the cooling system from the cylinders.

kristov

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?

kristov

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.