Hey gang. When I start my Formy, the oil pressure is around 45-50 psi. Once the engine warms up, it will drop to 28-30psi while cruising, and 13-15psi at idle in gear (at a stoplight). Under acceleration (light, moderate, heavy) it won't go over 30psi. My question is should I replace the oil pressure sending unit, or am I facing a possible failing/clogged oil pump? Anything else I might have a problem with? I've got 140,000 miles on it, and I change the oil VERY regularly, and have not noticed any "debris" in the old oil. Please help...I don't want to "kill" it!!

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'88 Formula 350
Bright (VERY bright) red. Mods? yep, but never enough!
New toy: '85 305TPI/700R4 Black T-Top T/A

 

definately check out the sending unit before anything else. ive had people bring me cars several times with low oil pressure thinking they needed an oil pump changed when it was only indication problems. with 140K and regular oil changes like you mentioned you may be ok. always check the easy/cheap possibilities first.

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85 IROC 350 11:1keith blacks,.555lift erson roller cam,1.5 crane roller rockers,edelbrock intake,holley 4150 750dbl pumper, nitrous oxide,full length heddman headers,true dual exhaust, 11"stall converter, 700R4, 3.73 locker

 

With that many miles, the bearings are probably getting a little loose. Change the sender to be sure that isn't causing the lower reading. The only accurate way to check the oil pressure is with a mechanical guage. If it isn't making any bad sounds I wouldn't worry about it. I've seen lots of cars with less pressure than that last along time before needing a rebuild. Example: My old cutlass w/305 chevy had barely any pressure at hot idle in gear(less than 5) with a mechanical guage. I ran it for 4 years like that and when I pulled it, it was still running just fine--installed a 350 olds.
Watch the oil pressure, if it suddenly drops at hot idle and stays there you may have something else going wrong.

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82 camaro--original steering wheel, brake/gas pedals, seats--everything else modified
82camaro

 

I'll add my vote to the sending unit first, but would advise that you verify the oil pressure with a mechanical gauge first.

It isn't uncommon to have sensor failures in the mode you describe, as BP stated, but it's best to be certain.

At anything less than 10 PSI you should be hearing lifter/valve noise, so I would check the pressure and expect the best.

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Later,
Vader
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"Fear is how I fall, Confusing what is real..."
Adobe Acrobat Reader

 

Thanks gang. The sending unit was what I was leaning towards; and the mechanical checkout is a good idea, just to make things right. With 140K, the engine is still tight (no "loose" noises), but getting tired.

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'88 Formula 350
Bright (VERY bright) red. Mods? yep, but never enough!
New toy: '85 305TPI/700R4 Black T-Top T/A

 

Mine does that too and my sending until is only a few months old.

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1984 z28 w/ a 357 cu in. monster engine which is looking like the posterchild for Edelbrock with the exception of the Holley 750vac... all the suspension stuff... 9-bolt posi disk is in...

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