93 full size Blazer 350 throttle body

Asked by GuruTWLXT Jun 18, 2018 at 09:10 AM about the 1993 Chevrolet Blazer Sport 2-Door 4WD

Question type: Maintenance & Repair

I have a 350 throttle body in a 93 full size
Blazer when the car is started at idle it
sounds fine as soon as I put the car in gear
the oil pressure goes down and I hear
knocking once I start driving put the car
back in park it sounds fine took one valve
cover off where I heard the noise and found
that the lifters aren't getting oil

103,225

KenF answered 6 years ago

High miles on the engine? The knocking/clacking and low oil indicator show loss of oil pressure. Loss of oil pressure can be from a few things: internal oil pump leak, external oil pump leak (pickup shaft to pump), hung up relief valve, oil filter failure, and worn bearings / excessive bearing clearances. For now, try switching to a heavier straight weight oil, and see if pressure picks up. If it does the loss of pressure is likely one of the reasons listed above, if it drops further, then the cause may be a leak on the pick up side of the pump. Usually, good oil pressure at idle then a loss of pressure at hotter temps indicates excess bearing leakage.

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