MrAdam

Hi guys. My 98 Suburban (4x4 5.7 Vortec) died on the highway yesterday. Towed it home and after pulling the plugs cylinder 3 plug looked sooty. The truck will only start with that plug removed, and it actually runs well on 7 cylinders. But I f that plug is reinstalled it won’t hardly crank a full revolution because of what sounds like a binding problem.

I pulled the valve cover and I don’t see anything noticeable wrong with those valve springs or rockers, even when cranking the engine. Anyone have an idea on how to proceed? Stuck shut valve, or a bent pushrod maybe?

thanks for any and all help! I’ve had this truck for 7 years and still love the thing.

oilcanhenry

A motor is just a pump of sorts, so it has to vent the exhaust flow. No chance anything fell into the combustion chamber? If something is plugging up the #3 exhaust, that would be a possibility. Frankly, I think something is amiss with your # 3 piston and/or the connecting rod, but a bent push rod or a shot hydraulic lifter could be it.

73shark

Welcome to the forum. Does the #3 exhaust valve operate when cranking the engine?

repairman54

Compression test with all the plugs out to see the overall condition. All should be within 10% of each other as a first step before any teardown.