Thread: Please help me understand this....

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Don't overlook a leak at the inside bottom of the intake at the interface of the cylinder head, where you may or may not find a leak with a sprayed flammable substance. Such a leak will allow oily vapors from the oil pan to be sucked into the intake port, disrupting air/fuel mixture balance and providing a vacuum leak. It will also foul the spark plugs with oil. If you find nothing pointing to a leak, pull the intake and examine the gaskets to insure that they are being pinched with equal force top and bottom, side to side. The manifold could have been mis-machined. If nothing is found there, examine the manifold for cracks. We used to use a Zyglo process back in the day, but there may be better ways today.

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