Head gasket or intake manifold?

[sunlady]

My '94 Sunbird has been showing the following symptoms that seem to indicate an internal coolant leak. The most obvious symptom is that she tends to start very roughly when the engine is cold- choking, misfiring, and trying to stall, unless you give her plenty of gas. After a few minutes of this, the engine smooths out, and seems to be running fairly normally. This rough starting sometimes seems worse when the weather is cold or damp. Gray steam out the tailpipe has been noted, but is not always present. There are signs of water getting into the oil, although not in great quantity. The rate of coolant loss is quite slow, and the car does not tend to overheat. My question is: Am I dealing with a head gasket leak, or with a leak in the intake manifold gasket, or something else entirely? What's the best way to find out for sure?

 

[melsg5]

Pressure test the cooling system to determine the source of the leak, it could be external. If it is cold and damp you will get white smoke coming out the pipe when the engine is cold. What exactly are the signs of water getting into the oil, do you see a creamy brown substance in the oil filler cap? What is the maintenance history of the car, are the air filter and fuel filter relatively new, how about the spark plugs? How about the plug wires? There are lots of things other than internal coolant leaks which can produce the listed symptoms.

 

[sunlady]

Response

In answer to your questions-I do see a small amount of moisture on the inside of the fill cap, and the oil does not look entirely clear-it get a murky look when the car has been sitting for an extended period of time, and if you check it again after starting the engine, it does have a milky aspect. (It seems as though the oil stays clearer when the car is being driven.) I changed the air filter last summer, but the fuel filter has not been changed recently. Back in December, the upper radiator hose sprang a leak while I was in town, and my dad and I ended up jury-rigging a temporary fix with a piece of flex hose in order to get the car home. The flex hose was a bit too big, and pressed one of the spark plug wires against the exhaust manifold, causing it to get burned, so I had to replace the wires. My brother looked at the plugs and re-gapped them, and said that they didn't need to be changed-except for Number Three, which was seized, and broke when he was taking it out, and messed up the threads, so that the hole needed to be tapped out. (All plugs and wires were last changed about 18,000 miles ago.) I know it's normal to get steam on cool mornings, but I have (sometimes) noted a little bit on warm, sunny afternoons, as well. I hope all this information is helpful.

 

[melsg5]

see nothing conclusive that you have a internal coolant leak. No compression test and you havent pressure tested the cooling system. There is nothing abnormal with some moisture in the oil cap. When the coolant which contains antifreeze mixes with oil you get a substance that looks like a chocolate shake.You can try cleaning the throttle body and replacing the fuel filter. In addition check the fuel pressure regulator vacuum line for any gasoline. If you see gasoline in the rubber line the fuel pressuer regulator needs to be replaced.

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[Mike D]

Head gasket

At 75K I began using coolant as if it were gasoline. At times it was blowing out of the tail pipe like a chimney but then would stop without notice. No apparent leakage into the oil thank God. Anyway the vehicle would idle rough when cool then smooth out when warm. After removing the head it was apparent that the gasket blew between 3 and 4. The head did not need to be reworked, just a new gasket and bolts. Hope your "bird" needs the same.
Mike