# Low oil pressure/oil light coming on



## etewald (Dec 27, 2011)

So I inherited my brother's '69(400, TH400 with a stage 2 shift kit, limited slip 3.23 gears) last year after he passed away. It hadn't been on the road in 2 or 3 years.
I got it running after dropping the gas tank and cleaning it out and replacing all the soft lines, an oil change, tranny fluid change, radiator flush and new plugs. Had to swap out the Quadrajet for one my buddy had sitting on a shelf because of a stuck float(the one I put on it was from a mid-70's chevy truck, and it wasn't kicking down quite right under heavy throttle, but I'm going to rebuild the original before it hits the road this spring). 
She ran fine after a good warming up, but about 1/3 of the time, after it was warm, the oil light would sometimes flicker and sometimes come on steady at idle. It would go off under acceleration. I don't have an oil gauge installed, although it's on the list of future upgrades.
I've researched it pretty well, and it seems I might have a gummed up oil passage. My question to you guys is this:is there anything I can try to get it unblocked other than tearing into the engine? I'm not ready for a pull/rebuild as it's not in the budget right now. Any flushes/additives you guys have had success with? Thanks in advance for the replies.

Eric


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## GTO JUDGE (May 14, 2005)

Oil Sending unit ok?


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## geeteeohguy (Feb 2, 2008)

My condolences for your brother. First, I would verify the sending unit by borrowing/buying a mechanical oil pressure gauge and screwing it in where the sending unit is. Verify that the passage there is clear. If you do indeed have low oil pressure, it could be a clogged pickup screen at the oil pump, worn oil pump, or worn engine bearings. First and easiest is to verify that it really does have low oil pressure.


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## jmt455 (Mar 26, 2012)

^X2

Good advice!


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## etewald (Dec 27, 2011)

As far as I know, the sending unit is good. Would a place like O'Reilly Auto have an oil pressure gauge to loan out?


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## BearGFR (Aug 25, 2008)

Replacing the oil pressure switch (which is what you have if you have a light instead of a gauge -- it's not a "sending unit") is relatively cheap. $5.99 at Autozone, and they're readily available.

Bear


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## etewald (Dec 27, 2011)

Well, my local O'reilly's doesn't have a loaner oil pressure gauge. Gotta make the rounds with my buddies and see if anyone else has one. I'll probably switch out the oil pressure switch while I'm at it if they're really that cheap.


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## geeteeohguy (Feb 2, 2008)

If nothing else, take it to a reputable shop and have it checked. You can buy a decent aftermarket mechanical oil pressure gauge anywhere for under $40.


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## chuckha62 (Apr 5, 2010)

If I recall correctly the factory sending units tended to go bad over time by having oil bypass the diaphragm. Once that happens, the oil pressure reads low or the light goes on. The sender is pretty cheap, might be just as easy to replace it. I got mine locally for $7.50.


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