Oil Leak Diagnosis
11-07-2007, 10:29 AM
#17
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Join Date: Aug 2003
Location: Naperville, IL
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I've had two cars in the shop in the last 6 months with a simlar issue, but different causes..
The first had a leaky oil-return tube. It would only leak when the engine was cold and had been sitting for a while. When the engine warmed up, the seal would get just flexible enough to work. Then once the engine got cold and the oil started pooling up down below, it would start leaking.
The second had a leaky top-end (breather, and oil pressure switch). Somehow the oil would pool up on the top of the engine, then when the customer parked it in his driveway which slanted to the right, it would slowly run out. We had a hard time believeing this, thinking that it should come out when running, but it wouldn't, at least not enough to notice. However once we fixed the leaks up top, the driveway drip" went away.
In most cases the engine still leaks while running, but most of the drips get burned away by the heat exchangers while running, so you only notice it when cold.
The first had a leaky oil-return tube. It would only leak when the engine was cold and had been sitting for a while. When the engine warmed up, the seal would get just flexible enough to work. Then once the engine got cold and the oil started pooling up down below, it would start leaking.
The second had a leaky top-end (breather, and oil pressure switch). Somehow the oil would pool up on the top of the engine, then when the customer parked it in his driveway which slanted to the right, it would slowly run out. We had a hard time believeing this, thinking that it should come out when running, but it wouldn't, at least not enough to notice. However once we fixed the leaks up top, the driveway drip" went away.
In most cases the engine still leaks while running, but most of the drips get burned away by the heat exchangers while running, so you only notice it when cold.
