How can I get my 1988 GMC pickup 5.7 liter engine to stop smoking?
I’m trying to get this high-mileage truck to pass smog. Spark plugs aren’t fouled and the PCV valve, plug wires and distributor are all in good shape. I’ve put high-mileage oil in and used a no-smoke additive and a gasoline additive without much change. I’m about to put a new catalytic converter on, but if I can’t get the engine to stop smoking, at least temporarily, I can’t smog because of “visible smoke”, which only occurs after running at moderate RPM for an extended period as part of the smog.
Runs great, interior in good shape, all accessories (heater, A/C, radio, lights, etc) are working well. I hate to give up on this truck.
I think you are flogging a dead horse. Oil is leaking past the rings and being burnt in the combustion chamber. Only a ring job will cure that.
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