low oil pressure
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New User
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low oil pressure
need some help I have a 1987 ford f 250. I did a complete rebuild on my engine (351W) For some reason one of my lifter collapses at idle. So I pulled the valve cover and notice no oil at idle. Before i started the motor for the first time i primed the pump with a drill and my gauge reg. go oil pressure. shortly after break in oil pressure droped. Instaled a mechanical gauge and at idle no pressure bring the idle up about 2200 RPM oil pressure maby 10 PSi. Any throughts oil pump was new.
Logistics Pro
Joined: Mar 2005
Posts: 4,698
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From: Mexico, Missouri
I'm gonna shoot in the dark on this one..
Perhaps an oil gallery plug was left out, or was loose. This same problem occured to another user in the 289, 302, 351 Small Block V8 Forum. I can't recall his name. Yet undoubtly, I don't remember him finding the problem either. I have heard of this happening when the block has been hot-tanked, and the Machinist knocks out the plugs behind the timing chain on Chevy.
I don't know for sure what all consisted of your rebuild or parts used. Another thought is the dizzy gear is perhaps mismatched or other. Not knowing what was involved in your rebuild...it's a needle in a haystack.
I would post back with "Rebuild" info and also, hopefully another member can chime in with more wisedom.
Perhaps an oil gallery plug was left out, or was loose. This same problem occured to another user in the 289, 302, 351 Small Block V8 Forum. I can't recall his name. Yet undoubtly, I don't remember him finding the problem either. I have heard of this happening when the block has been hot-tanked, and the Machinist knocks out the plugs behind the timing chain on Chevy.
I don't know for sure what all consisted of your rebuild or parts used. Another thought is the dizzy gear is perhaps mismatched or other. Not knowing what was involved in your rebuild...it's a needle in a haystack.
I would post back with "Rebuild" info and also, hopefully another member can chime in with more wisedom.
Posting Guru
Joined: Feb 2010
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From: CASA GRANDE AZ
is the pick up tube on good as in the pump might be sucking air at the joint ? also did the engine get new cam bearings ? if not you will lose pressure there as well ! do you have the right size drive rod in the pump from the distributor ?
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I did have the machine shop put in new cam barings the engine was bored .30 new pistons rings bearings timing chin and gears and new oil put. I did plug all three of the oil gallies up front. The oil pressure wil climb to about 10 psi at 2000 rpm but at idle 0 psi.I did prime the pump before starting and the gauge showed normal pressure.
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If i had an oil galley plug come out in the valley under the intake would it have oil pressure up to that point. When will the sending unit pick up the pressure after it passes through all the lifters? It seems that the lower end is getting oil because there is no noise out of the bearings just the number 5 lifters at idle. Pulled valve cover on that side and oil is getting to the back side but not up top at idle. If i rember correctly if forgot to put rtv on that valley plug under the intake.
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Joined: Nov 2010
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From: Graniteville
At only 10psi/2200rpm and 0psi/idle, I would be pulling the motor apart and checking everything out, especially the bearings. Even with no noise, there is a good chance you have already wiped the bearings 
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wouldn't the bearings be making noise? Also when i pulled the sending unit a good amout of oil would come out when i turned the motor over.
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Elder User
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From: Graniteville
On a rebuild, they may not be making noise yet, but still have wiped the surface. Turning the motor over with the sending unit out shows you the pump is trying to work, but for some reason not able to build pressure, whether its a bad pump, missing/leaking galley plug, etc. The oil being pumped is going to take the path of least resistance. That being the case, wherever it is loosing pressure at, is less resistance than pumping thru the bearings and journals
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Thanks for your adive wife is going to flip if i have rebuild this thing agian. If one of the galley plugs came out and I replace it and use a drill to turn the pump an the pressure comes back up do you think i be ok!
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What will the bearings look like if they are damaged? I work 24hr so when i get home i going to drop the pan and work my way up. it seem to have oil down low just could get it to the front cylinder (# 5) lifter ticking at idle is what gave it away it did run long enough that the motor should have crap out about a 1/2hour to a hour becaus i drove it around the block and when i let it idle a few minutes is when the lifter would make noise. bring up rpm and it would go away. At cold start it would have about 20 psi.
Post Fiend
Joined: Nov 2008
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From: McKenzie River
If you see metal flakes in the oil...........It was a expensive learning experience.
Since you have some oil pressure, and have not run it too long........Its probably OK.
Concentrate on finding the restriction of oil press.
Since you have some oil pressure, and have not run it too long........Its probably OK.
Concentrate on finding the restriction of oil press.
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oil seems to be clean change after break in and it didn't have any metel flakes. thanks for everybody input i will be sure to keep ya all posted on the out. I hope a 10 cent part from china didn't destroy a good motor.