Hi,
i recently bought a 96 Camaro which shows signs of overheating. Temperature is NEVER under 100°C on the gauge, driving at low speed, and will increase as soon as I start to rev the engine. The consequence = I can just use the car from little runs in the town. If I want to take the road, i can't : driving over 120 km/h make temperature so hot, the coolant boils and i lose it from the radiator cap. I also have to drive the car with A/C always on the help temperature stay the lowest possible.

Now about the car and since i discover this problem :

* we check the water pump : OK,
* radiator has been open and cleaned carefully,
* i check both fans runs
* some people though the thermostat could be a problem and they removed them from the car: it hasn't changed anything (but i also ask for a new one)
* catalytic converters have been removed also from the car. I have no "service engine" visible anyway,
* I noticed also an excessive gas mileage (I never succeed doing more than 300 km with 1 full tank), and the engine is able to reved about 6500 rpm. I wonder if PCM has been modified

Please, please, give me your advices on this problem which don't allow me just make little runs with the car.

Waiting for answers,

Pierre
New Caledonia, South Pacific Ocean

 

Is the Air Dam missing or broken?

 

Make sure no air in system by opening the bleed screws. There should be no bubbles or hissing indiacating air in the sytem. Keep them open until just coolant and no air is coming out.

 

check your electric fans, Bleed the system, flat out REMOVE the t-stat (for testing purposes) make sure you have the air dam in the front attatched,

how do you know your water pump is good? those blades do corrode... just did this on my jeep... looks fine from the outside, but opened it up and looked at the blades and they were corroded down to nothing...

but make sure you BLEED the system first... then go from there.

JOe

 

and the best way to keep the motor colled off is to run with the heater on, not a/c.

 

make sure that the temp sensors are working properly check here http://shbox.com on how to make sure they are working properly

 

Since the cats are removed on your OBDII car and there's no SES light, and you can rev the engine to 6500... you've definitely got a modified PCM. Try to find out what other stuff has been modified with the car.

Probably the most common issue with the LT1 engine's cooling system is getting all the air out of it after a coolant flush, etc. The engine uses reverse-flow cooling (backwards to most other cars) that can be difficult to bleed successfully.

 

I thought you run the AC because it kicks on the both fans, instead of just 1.

 

Agreed, especially in this case with an overheating engine... but I've occasionally been able to cool the engine down a bit by turning the AC on - of course only because the AC will turn the rad fans on. Now the car is programmed for the fans to turn on earlier than stock, plus I have a manual switch, so I don't need to use that "trick", but it worked in the past.

 

thanks for all the answers.

the coolant has been flushed and air carefully bleed and checked several times after.

I haven't noticed any special thing looking as an Aia Dam .... i will check there weren't any been removed (hard because only TWO Z28 here and the other is don't working anymore).

Since PCM might be modified, maybe a too rich combustion (or too lean) might also be a problem.

I'm checking for all.

I noticed no one told me running without thermostat can be a problem.

Thanks again for answers. If new suggestions, i will consider them.

 

It's possible you have a blown head gasket. If you have the means you should get a leakdown test done on all cylinders.

 

about water pump : i have opened it : all was normal in it.

about blown head gasket : how to make a leak test on each cylinder ?

Pierre

 

Google is a wonderful thing.

http://www.type2.com/library/engineg/leaktst.htm

http://www.650motorcycles.com/LeakDownTester.html

http://www.xs11.com/tips/misc/misc3.shtml

Not sure if any of these parts are available where you live? You can also take it to a shop (again.. if there is one anywhere near you) however you may have to pay through the nose especially since it's such a PITA to use a leakdown tester with most of the spark plug holes.

 

The "air dam" is the plastic wing under the front of the car (the thing that hits every time you go over a high speed bump or curb.) It serves mainly to force the air while driving up into the radiator area. If it is missing or badly damaged and no longer able to provide this function it has been known to cause execessive heating.

 

I will be gone a few days. I've just looked at the air dam. Nothing seems wrong with it.

I have check for possible leak at head gasket with same kind of stuff mounted on radiator while engine running. People told me pressure would not stay constant doing that if there were any leak (and it was constant)

See you in a few days