Blown Head Gasket?

**MNGPGT** · 09-18-2012

My girlfriend's 1997 Grand Prix GT has been running hot on and off all summer long. So I finally decided to try to solve the problem with it. I noticed the intake doesn't have any GM markings on it so I assume its a Dorman replacement. I flushed the coolant, changed the spark plugs (needed a tune up) changed the thermostat with another 195* and bled the air out of the system. Now it runs hotter and overheats quicker than before! Maybe I bought a defective thermostat? I noticed no coolant mixing with the oil or oil in the coolant reservior. A friend who lives 100 miles away said that he feels its either a bad thermostat or a head gasket. I took the car to a garage where they claimed to have tested the coolant for exhaust gases and it came up clean. The service writer said it was overheating due to a leaky coolant elbow? I find it hard to believe that air could enter a pressurized system through the coolant elbow (very small leak) and cause the car to overheat so quickly! The coolant is not low. The car can not be trusted at idle or driving. How to I determine the cause of this? Please help

**GTPSHAWTY** · 09-18-2012

didnt see anything about a waterpump... their cheap.. try that and its very uncommon to blow head gaskets in these cars.. i ran mine hot 10 times due to no service and in the middle of nowhere in the middle of the night.. put water in it.. change LOWER INTAKE MANIFOLD GASKETS and elbows... drove fine

**matt5112** · 09-18-2012

The water pump spins any time the belt is.

And the diagnosis sounds more accurate than your assumption.

Do a leak down test and a cooling system pressure test. Don't make assumptions.

**MNGPGT** · 09-18-2012

Originally Posted by matt5112

The water pump spins any time the belt is.

And the diagnosis sounds more accurate than your assumption.

Do a leak down test and a cooling system pressure test. Don't make assumptions.

I have no access to either of those tools. I also lack an air compressor. I would have to go to a garage again. I'm out of money right now. This really sucks!

I don't understand how air could get into a pressurized system through the coolant elbow! Is that possible?

**MNGPGT** · 09-18-2012

I also have my doubts that the garage tested the coolant for exhaust gases.

**Sven the Sexman** · 09-18-2012

Head gaskets are rare on these cars. The coolant elbow leak would allow the system to not be fully pressurized and pull in air instead of coolant during the cooling process. Repairing the coolant elbows is a good start, try bleeding the system out more, turn the heat on and make sure it is adequate. Typical stuff. I'm one of the few to blow a HG on the 3800...and it took a 96* day stuck on a highway with a blown radiator to do it.

**matt5112** · 09-18-2012

how so?

i've been asked for the same crap at work.

don't have it, but it exists.

**MNGPGT** · 09-18-2012

Originally Posted by matt5112

how so?

i've been asked for the same crap at work.

don't have it, but it exists.

I have my doubts because it was a freebee. I dropped the car off and was told it was a coolant elbow that was causing the overheating. He ruled out the intake or the headgaskets as the cause. I'm just not sure about it, seems too good to be true!

**MNGPGT** · 09-18-2012

Originally Posted by hitman92499

Head gaskets are rare on these cars. The coolant elbow leak would allow the system to not be fully pressurized and pull in air instead of coolant during the cooling process. Repairing the coolant elbows is a good start, try bleeding the system out more, turn the heat on and make sure it is adequate. Typical stuff. I'm one of the few to blow a HG on the 3800...and it took a 96* day stuck on a highway with a blown radiator to do it.

About how high did the temp gauge get when it overheated? I've seen this car get as bad as 240-250* at around 3/4 of the way!

**Sven the Sexman** · 09-18-2012

Mine pegged and remained pegged until I got off the highway.

**MNGPGT** · 09-19-2012

I'm going to use a product called a block tester to rule out the head gaskets once and for all. This product works by draining the radiator down to halfway. Fill with blue fluid to the line and use the suction head to draw up any hydrocarbons that may be present. If the fluid turns green or yellow, youre screwed. I won't get a chance to do this until Friday. Lets hope it stays blue! I'll update my results later.

NAPA AUTO PARTS

**BillBoost37** · 09-19-2012

You said the intake was ruled out?

**MNGPGT** · 09-19-2012

Thats what they said but I dont trust it. Ill test the head gaskets and if they are good, replace the coolant elbow for ****s and giggles. Then im going to do lower intake gaskets

**Scottydoggs** · 09-19-2012

the elbows cost 5 bucks and 30 minutes of your time, why not start where a known problem exists and go from there.

a compression test would be cheaper too. free tool rental at the parts stores.

when i bleed my car i like to let it idle till the fans come on, (rad cap open the whole time) that way you know the t stat opened up when your bleeding it.

also flushing the coolant is always a good idea, coolant dont last forever and if you have dex cool in it it does sludge up.

you can pull the lower rad hose off the engine, (its easier then off the rad) dump the rad and let the engine drain out.

remove the upper hose from the rad, remove the t stat housing, remove the t stat. put the housing back on ( no t stat installed) with the upper hose pushed down to the ground, into a bucket if you like.

you can also fill and dump the rad a few times to make sure its clear as well. hold your hand over the lower hose, fill it, let it drain out as fast as it will come out. repeat. you can fill it from the upper hose side too if you like.

now put the lower hose back on the engine, put a garden hose in the radiator and turn the hose on, start the car, run it till clear water comes out of the upper hose.

to re fill it, all i do is pull the lower rad hose off, drain the water out again, put the hoses back, the t stat back, then i dump 1 gallon of green coolant, full strength into the rad, top it off with water, done, it will mix all by its self. then bleed as described above.

if you like you can also fill the lim via the t stat hole to fill the lim up good. then put the t stat back in and then the housing.

**MNGPGT** · 09-21-2012

Replaced coolant elbow. Block test finished and headgaskets are good. Lower intake manifold gaskets may be leaking but that couldve been from when I took off the thermostat housing to drain coolant for the block test. The reason why it "ran hot" wasn't because it was running hot, it is a faulty gauge!

**Scottydoggs** · 09-21-2012

that will do it.

**steelholder** · 10-02-2012

i just took my 07 prix to the shop and they said i had a blown head afte only over heating one time for about 3 min while exited the freeway..could it happen this fast?? ive heard its really hard to, they did the test for exhaust gas and said it came up positive for blown head. I also have a leak in my coolant elbow, can someone help me out please

**Scottydoggs** · 10-02-2012

http://www.grandprixforums.net/how-c...ows-49779.html

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