Head gasket question
04-17-2012, 09:28 AM
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There are several things you can check to see if you have a head gasket issue.
-oil in the coolant/coolant in the oil:
Both oil and water circulate through the heads. If the gasket fails, the two can mix together. This is extremely bad for the motor as it stops the engine's ability to properly lubricate itself. Dead giveaways of this are water found in the oil when doing an oil change or an oil mixture in the coolant overflow tank.
Note: coolant can appear dirty or rusty from normal use. If your water has oil in it, you will be able to tell.
-thick, white smoke from the exhaust:
Thick, white smoke consistently leaving the tailpipe can be an indicator of a failed head gasket. A bad gasket lets coolant into the combustion chamber where it is burned, creating white smoke. Note: by thick, I mean really thick, as in blinding to drivers behind you. Don't confuse this with normal exhaust smoke (condensation) when you car is simple warming up.
-Low compression:
The head gasket's job is to seal the head to the engine block. If it can't do this properly, the engine will loose compression in the cylinders. The engine will feel like it's not doing as much work as it should be. It'll just seem lazy compared to usual. To see if your car has lost compression, find the correct rating for your car and test with a compression gauge. All you have to do is take out a spark plug, screw in your gauge, and crank the motor (but don't start it). Repeat for each cylinder.
Note: cars can naturally lose some compression over time, so don't freak out if it doesn't exactly match Audi's specs.
-oil in the valley (only on the 12v v6!)
For some reason, Audi put an oil passage extremely close to the inside of the head on the 12v v6. Unfortunately, this means it is very easy to to develop a leak at the inside edge of the head gasket on the driver's side head. The only way to stop the leak is to replace the head gasket.
Note: all Audi V6s are notoriously leaky oil-wise. Another common place for the 12v to leak from is the valley pan gasket. The head gasket oil passage will gush oil when the motor is running, so you'll be able to tell if you're screwed.
If you have the V6, the head gaskets are not too horrible to change depending on how mechanically apt you are. You will need the gaskets and new head studs. You will also need to have the heads planed at a machine shop before you reinstall them. Might as well do the timing belt at the same time because you'll have to take it off anyways. But before you jump to any conclusions, check your coolant and compression, especially compression. If you have any questions about the head gasket job, tools, etc. feel free to ask.
Oh, and if you have a four or five cylinder, sorry for wasting your time with all the V6 stuff lol.
-oil in the coolant/coolant in the oil:
Both oil and water circulate through the heads. If the gasket fails, the two can mix together. This is extremely bad for the motor as it stops the engine's ability to properly lubricate itself. Dead giveaways of this are water found in the oil when doing an oil change or an oil mixture in the coolant overflow tank.
Note: coolant can appear dirty or rusty from normal use. If your water has oil in it, you will be able to tell.
-thick, white smoke from the exhaust:
Thick, white smoke consistently leaving the tailpipe can be an indicator of a failed head gasket. A bad gasket lets coolant into the combustion chamber where it is burned, creating white smoke. Note: by thick, I mean really thick, as in blinding to drivers behind you. Don't confuse this with normal exhaust smoke (condensation) when you car is simple warming up.
-Low compression:
The head gasket's job is to seal the head to the engine block. If it can't do this properly, the engine will loose compression in the cylinders. The engine will feel like it's not doing as much work as it should be. It'll just seem lazy compared to usual. To see if your car has lost compression, find the correct rating for your car and test with a compression gauge. All you have to do is take out a spark plug, screw in your gauge, and crank the motor (but don't start it). Repeat for each cylinder.
Note: cars can naturally lose some compression over time, so don't freak out if it doesn't exactly match Audi's specs.
-oil in the valley (only on the 12v v6!)
For some reason, Audi put an oil passage extremely close to the inside of the head on the 12v v6. Unfortunately, this means it is very easy to to develop a leak at the inside edge of the head gasket on the driver's side head. The only way to stop the leak is to replace the head gasket.
Note: all Audi V6s are notoriously leaky oil-wise. Another common place for the 12v to leak from is the valley pan gasket. The head gasket oil passage will gush oil when the motor is running, so you'll be able to tell if you're screwed.
If you have the V6, the head gaskets are not too horrible to change depending on how mechanically apt you are. You will need the gaskets and new head studs. You will also need to have the heads planed at a machine shop before you reinstall them. Might as well do the timing belt at the same time because you'll have to take it off anyways. But before you jump to any conclusions, check your coolant and compression, especially compression. If you have any questions about the head gasket job, tools, etc. feel free to ask.
Oh, and if you have a four or five cylinder, sorry for wasting your time with all the V6 stuff lol.
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