pippintook

I have a 91 Firebird Forumula with 305 TBI/Auto. I am getting a bad coolant leak from back of driver's cylinder head. The leak is definintely NOT coming from the intake manifold gaskets, the rear block freeze plug, or the oil filter switch. I can not pinpoint the exact location of the leak as it is extremely difficult to try and view the area. From the top, I can not see where back of drivers head meets with block. From underneath the car, I can see that the cylinder head is slightly shorter than the cylinder block (by a few inches). The leak appears to be coming from the mating of the driver's cylinder head and block...right at the back of the driver's cylinder head....The leak appears to get worse when engine is hot and RPMs increase. The engine is running above normal temp. Ther is not really much white smoke of of the exhaust. The engine is running pretty good and has decent power. I am getting a small stream of coolant spraying out and/or dribbling of coolant. I have thoroughly checked all coolant lines and there is no coolant line in the vicinity of the rear of the driver's side cylinder head. Engine still starts and runs properly. After engine shutdown the leak hisses loudly and shots out steam/coolant
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History: I purchased this car from a friend...my friend told me the car was going through a gallon of coolant every 2000 miles...so I knew there could be a possible gasket issue. He sold me the car very cheap. Engine recently passed an etest easily. I pulled the cap a few weeks ago and noticed some bubbles in the coolant...kinda of like a burb every 10 seconds or so?.....oil is pretty clean and not contaminated.....I have not performed a compression test or done any diagnostics so far.

Questions
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1. Has anyone ever seen a head gasket leak at this location (rear of drivers head where head meets block)?
2. Is this common for a head gasket to leak where a steady stream of coolant is emitted?
3. Any other advice / comments is appreciated.

Slow89Iroc-Z

pull the intake and inspect the gasket. If it looks to be comming from the crossover ports in the heads then reinstall the intake with a new gasket and remember the silicone around the ports. If the intake looks not to be leaking...pull the manifold, accessories bolted to that head and zip the head off and reeplace the gasket.....

five7kid

iTrader: (14)

Since you also made this statement, "I can not pinpoint the exact location of the leak as it is extremely difficult to try and view the area," how do you know it's not coming from the intake manifold gasket? I've seen more than one leak from there. It will dribble down the head/block mating surface and make it look like it's coming from there.

That sounds like a head gasket, or more likely, a cracked head.

Red Devil

Coolant system tester and a kit with dye and UV blacklight will test then pinpoint it as quick as your car can reach temp.

To test for cracks in the head or blown head gasket (or more to remove them from the picture) you can always do a leakdown and/or compression test.

pippintook

I can get a pretty good look at the intake gasket and I am pretty sure that the intake gasket is not leaking anywhere. What I can see is a very tiny small stream of coolant that is coming from the rear of the driver's head near the mating surface of the head/block. While the engine is running I can see this small stream of coolant from underneath the car. I can not see exactly where it is coming from as it is very hard to get a mirror up there...as it is very tight and exhaust is hot and coolant is being sprayed out....so, I just see the small stream of coolant...but not exactly where the small stream of coolant starts. After I shut off the engine the stream of coolant stops and just hisses and blows out steam. So, I am pretty sure the leak is coming from the back of the head at mating surface of head and block. I will do a compression test and see what are my results.

Wayne's 383Iroc

I seen a 87 305 do the same thing on the P-side and it was the head gasket. It was leaking and running down the back of the block.

firechicken_3

iTrader: (4)

it still could be from the intake to head mating surface, and since the intake must be removed to get to the head, just make sure to carefully remove and inspect its gasket area, just to be sure its not from there, no reason to do all the extra work if not needed, but at the same time, may be worth it to go ahead and pull the head to if its not definately an intake issue