Question about 1986 Mazda 626 Coupe
The last time I drove the car it was running fine. No missing, no overheating etc. The next day when I started the car it was missing on one cylinder and had what looked like steam coming out of the exhaust pipe and it smelled really bad. I checked the oil and found what I thought was engine coolant mixed with the oil. I drained the coolant from the engine and the oil because I did not want any water/antifreeze mixture in the crankcase. I replaced the oil in the engine but did not refill the radiator with any coolant. I did start the engine and run it for a short period of time without any coolant and it ran fine with no missing or steam coming from the exhaust pipe. I performed a compression test on the engine and found that all cylinders had approximately the same reading (120-122). Initially I thought it must be a cylinder head gasket or a cracked head allowing coolant into the cylinder but the readings on the compression test did not show once cylinder with a significantly lower compression than the others. The car is a 1986 Mazda 626 turbo 2.0 liter. It has never been overheated because I am the only person to drive this car. Any ideas on what might be causing this problem?
Water inside pistons increases compression, You do not have bad piston rings and not burn out intake or exhaust valves, your compression is fine, but You have a blown Head Gasket or a crack for sure
Posted on Jan 22, 2009
The ONLY way coolant can get into the crankcase is through a crack in the cylinder head, block, or head gasket. THE ONLY WAY!.
Checking compression was a good idea, and you've confirmed that is not where the leak is. It could be somewhere else within a head, the block, or head gasket.
Any gasoline engine will blow steam from the exhaust pipe on start-up and a few minutes running. May even stink, depending on how sensitive your nose is to smell.
I think your going to have to dig deeper into this, if you truly had coolant in the oil. But to tell you exactly where to look is not going to be easy.
Posted on Jan 22, 2009
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Posted on Jan 02, 2017
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