1987 Ford F-150 No oil pressure after my trucks warms up

BIGWORM24277

MEMBER
1987 FORD F-150
V8
2WD
AUTOMATIC
150,000 MILES

I have 87 f150 5.0 v8, it looses oil pressure after warming up, unless gas is being applied. I thought it was just the factory gauge, so I replaced it with a aftermarket sun pro oil gauge. It is still doing the same thing, it holds 40psi when cold and nothing after it warms up. My question is if I replace the oil pump should this fix the problem? And should I go ahead and replace the main bearings? I thought maybe the screen might be stopped up also. Any info is greatly appreicated

5 Replies

BUDDYCRAIGG

MECHANIC
2,262 POSTS

You didn't say how low your oil pressure is getting.

A safe range is 10psi for every 1000rpm.

If it's going below that, then yes you need to look in to repairing the problems in the engine.

Oil pump,
possibly main and crank bearings,
possibly cam bearings.

As a band-aid fix, you could try a thicker oil
most fords call for 5-20 or some crazy thin oil.
Try 10-40.

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Friday, January 2nd, 2009 AT 10:56 PM

BIGWORM24277

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3 POSTS

The oil pressure at idle after truck warms up is 2psi and below! Would 20w 50 be to thick of a oil to use?

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Friday, January 2nd, 2009 AT 11:08 PM

BUDDYCRAIGG

MECHANIC
2,262 POSTS

20-50 would be fine, but you may notice a very slight decrease in MPG.

I put 20-50 in GM 2.8, 3.1, and 3.4 engines all the time because they have weak crank bearings.

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Friday, January 2nd, 2009 AT 11:19 PM

BIGWORM24277

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3 POSTS

I went out and bought main bearings, oil pump, oil pump screen, oil & filter and oil pan gasket. So hopefully that fixes my problem. Is $200.00 an average price to pay to have this work done? Thats what my i'm getting charged.

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Sunday, January 4th, 2009 AT 1:29 PM

BUDDYCRAIGG