How to check for blown head ?
Thread Starter
Instructor
Joined: Jan 2002
Posts: 245
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From: Newport News VA
How to check for blown head ?
I have a 94 LT1 automatic. I was recently looking into having the coolent changed and noticed that there's a brown sludge in the recovery tank. I figured it was dirt. During the summer while on the interstate, the temp got to 250, I don't know why as I've never had a problem with temp scared the hell out of me. I replaced the thermostat with the GM part and it's been fine. Any ideas ?
Team Owner
Joined: Dec 2000
Posts: 90,675
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From: SE NY
Cruise-In II Veteran
Re: How to check for blown head ? (9T4YY1)
Was there ever any coolant in the crankcase?
You can use a compression check to look for a blown head gasket along with a pressure check of the radiator.
You can use a compression check to look for a blown head gasket along with a pressure check of the radiator.
Racer
Joined: Nov 2002
Posts: 300
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From: Perth WA
Re: How to check for blown head ? (9T4YY1)
I have the same thing. I have been chasing an overheating problem for months. Went to the radiator place and they can test to see if you are getting Exhaust gasses in the coolant.
My engine was running fine and I had no coolant in the oil or blowing smoke. I just kept overheating when the car got a thrashing. I started to get suspicious when I still had the problem after changing radiator, water pump, thermostat, heater hoses and adjusting fan cut in temps.
Basically what is happening is exhaust gases are being pushed into the cooling system via a cracked head or blown gasket, so you end up with an air pocket in the block and then the thermostat won't open because it has air behind it not water.
I haven't pulled mine apart yet, but I have ordered new heads just in case as I was going this route eventually.
Good Luck. If it is the just the gasket, you will be lucky.
My engine was running fine and I had no coolant in the oil or blowing smoke. I just kept overheating when the car got a thrashing. I started to get suspicious when I still had the problem after changing radiator, water pump, thermostat, heater hoses and adjusting fan cut in temps.
Basically what is happening is exhaust gases are being pushed into the cooling system via a cracked head or blown gasket, so you end up with an air pocket in the block and then the thermostat won't open because it has air behind it not water.
I haven't pulled mine apart yet, but I have ordered new heads just in case as I was going this route eventually.
Good Luck. If it is the just the gasket, you will be lucky.
Racer
Joined: Jun 2003
Posts: 308
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From: San Antonio TX
Re: How to check for blown head ? (timallard)
Do you have the orange "Dex-cool" stuff? If so, I don't think its a problem. My '96 Firebird has the Dex-cool, which is supposed to be good for 100k miles. I've had it completely flushed and refilled a couple of times and within months it developes the brown sludge in the recovery tank.
If you don't have the Dex-cool, a blown head gasket will have some pretty tail-telling symptoms. First, the oil is very easy to see in the green anti-freeze. Next, your oil will look "milky." Third, your car will smoke a lot, due to the water and antifreeze being burnt off by your engine.
Have you ever pulled your radiator for a good cleaning or changed the thermostat? If not, these would be the first things to do.
[Modified by HapAFcop, 7:33 PM 11/25/2003]
If you don't have the Dex-cool, a blown head gasket will have some pretty tail-telling symptoms. First, the oil is very easy to see in the green anti-freeze. Next, your oil will look "milky." Third, your car will smoke a lot, due to the water and antifreeze being burnt off by your engine.
Have you ever pulled your radiator for a good cleaning or changed the thermostat? If not, these would be the first things to do.
[Modified by HapAFcop, 7:33 PM 11/25/2003]
