I've got a little problem with my daily driver, which, alas, is not a traditional hot rod. But this is the only board I'm a member of and there's a lot of engine know-how here, so I thought I'd throw it out there. My daily driver is a 90 Vette, and the problem just started yesterday. Whenever I go around corners or when I brake a little harder than normal (basically, putting some g-loads on the car, but not accelerating), I lose oil pressure. It only lasts as long as I'm cornering or braking, and it goes right back up when the car is level and stable again. My first thought was that it might be a low oil level, but I checked it, and it's full and clean. So I don't know what the hell it is. Anybody with some SBC knowledge out there got any ideas? Thanks ahead of time, guys.
It this really hard cornering and braking? I've seen them act that way when the pickup has come off...
return pasageways could be gummed, so when running you don't have enough draining back down to feed the pump.
It's happening without hard cornering or braking. If I take a corner anywhere near the Vette's potential, the oil pressure briefly drops to zero and lights up my check guages idiot light (btw, no shit Chevy!) which scares the crap out of me. The last thing I need to do is grenade the motor in my daily like I did to my 47 Roadmaster back in high school... I thought about the pickup having fallen off and the return passages being gummed up, but wouldn't that affect your oil pressure all the time? It seems to run fine pressure when I'm just cruising or standing still. Are these problems common to SBCs? Any other ideas? And thanks guys for indulging my late-model questions.
It really does sound like the classic SBC prob of pickup off--the pump is low enough to get oil under steady conditions, but is maybe 1-1 1/2" higher than where the pickup usetawas so is uncovered under G loads. Put in an extra quart and see if the problem needs harder braking to occur...if so, I think we have found the problem. If it were mine and the diagnosis were to stay where it is, I would hook up a temporary mechanical gauge just to be real sure the sensor or wiring aren't loose or infested with evil spirits before going to work. This would be a lot of work if found to be unnecessary... If this is the problem, during the repair festivities, weld a bit of steel strap to the pickup and run it to a pump cover bolt as a safety...also loctite the press in part.
sounds like you nailed it.... also I had one years ago that broke the round pickup off of the tube, acted the same as if the pickup had fallen out of the pump.
Thanks for the ideas, guys. This car has had an oil pressure guage issue before, so it would be prudent to hook up a manual guage just to make sure. Ugh, the thought of trying to get the pan off the vette is killing me. Likely that's what I'm going to have to do.
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