Thread: 79 305 oil pressure issue

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I have a 79 El Camino with a 305. Running at idle it has oil pressure. Driving is the same. Hard acceleration and shifting normally (automatic) pressure drops then comes back up. I think the pump is bad. Ideas before I tear into it??

Originally Posted by Shawn1

I have a 79 El Camino with a 305. Running at idle it has oil pressure. Driving is the same. Hard acceleration and shifting normally (automatic) pressure drops then comes back up. I think the pump is bad. Ideas before I tear into it??

We had a similar problem recently and it turned out to be a bad oil filter. My advice, purchase a Wix, K&N or Napa Gold filter and change the oil. See what happens.

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Thanks, I'm loosing oil somewhere, next is a compression test.

oil drain back holes plugged with bits of drbries from old valve stem umbrella seals or sludge. oil doesn't drain back fast enough at higher rpms

Shawn, welcome to the forum.

Just to keep people from chasing false trails, what is the history of your El Camino engine? Has it been rebuilt, and if so, when, and how many miles since it was freshened? If it's an original Jerry's suggestion of the oil drain back holes being plugged is a really strong possibility.

Nylon pieces from timing chain sprockets are notorious for clogging oil passages and pickup screens. I don't know if nylon tooth sprockets were still being used in 79- assuming it's the original engine.

If so, the pickup screen can be cleaned, carefully. If you accidentally pop the screen in, opening the bypass orifice, then it's garbage, you'll have to replace it and the timing chain and sprockets.