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Re: 98 GMC 5.7L misfire
Posted to Technical Discussion Forum on 4/18/2003

Hi Brian. The deposits appear to be oil from either a leaking intake gasket or valve seal/guide concern. Try pulling the PCV valve and then check for vacuum in the crankcase at idle. If the leak is large enough, you may hear it whistling from the crankcase. Wi... Login to read more.