Oil pressure problem
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Oil pressure problem
I just got a my 88 f250 with 4.9 EFI 4 speed a few weeks ago and it runs great an drives fine. But after its warmed up an idles the oil pressure drops to Zero but if the rpm's are above 900 there fine. I even replaced oil pressure sending unit. So im at a stand still on what i should , i thought about runing a heavier weight oil. It is a high mileage engine about 210,000. I also thought it could be a bad pump or the screen gummed up. But any help or advice is great
Post Fiend
Joined: Jan 2000
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From: Metro Detroit (Redford)
This does not sound normal and I never heard that these motors do that. I wonder if the oil pressure gauge is not very good. Your year may have a real gauge, but a lot of Fords in the last 15 or so years have a dummy gauge. You need to get a mechanical oil pressure gauge hooked up and see what really is happening. If it really was dropping to zero, I think you would have also posted that the engine fried itself. Or maybe you shut it down then. Anyway, see what the real oil pressure is and then we'll take it from there. What does the existing gauge show in psi, or is it not numbered? If it is a cheap gauge it might look like zero but still have 5 or so PSI.
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its a needle gague i think its a real one because it has normal in the center on the gauge an it usally stays at half way point on the gauge. I have thought about using a mech gauge on it an see what it does not sure yet. But if it is loosing pressure after i had been runing for an hour or so you think it might be a bad main bearing. And you know also know what a ball park prices is on a used one? because i cant put to more in this truck because all i need it for is a daily driver. I know when the pressure drops the engine light kicks on then i get teh rpms up a little it goes back to normal. But i dont hear and dry knocking or anything. I thought it might also be a weak pump because its not sealing very good to pump the oil when its at a higher temp.
Last edited by dukemaster; Nov 30, 2006 at 11:50 AM.
Post Fiend
Joined: May 2004
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From: Lakewood, Ohio
it is an idiot light trying to be a gauge. it has a resistor that keeps it in the center unless the pressure drops below 7 pounds.
get a mech. gauge to check out real oil pressure.
more than likely a clogged pickup screen.
many posts on this very same problem.
get a mech. gauge to check out real oil pressure.
more than likely a clogged pickup screen.
many posts on this very same problem.
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yea im gonna drop the pan an check the pick up an install a mech gauge also and see how that goes. I hope thats just the problem the gauge is nutz. Because i dont want to put anymore money into than i have to.
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Post Fiend
Joined: Jan 2000
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From: Metro Detroit (Redford)
Much easier to install mechanical gauge than to drop the pan (PITA). Do the gauge first. They are about 17 bucks at chain parts store (Sun brand). All you need to do is hook up the tube and mount it on steering column (see mine in gallery) to get the pressure. Hook the light up later when you get free time. If the pressure really is bad, then pulling the pan is next step. My truck had a half clogged pickup at 65K miles (previous owner did this). A real oil pressure gauge should move up and down some with rpm, not just always stay in the middle. My wife's Aerostar has the bogus dummy gauge and it sometimes rides only 1/4 the way into Normal zone. I figure just cheap electronics.
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Post Fiend
Joined: Jan 2000
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From: Metro Detroit (Redford)
You probably could get a good electrical gauge, but it is more to install IMO. Need good electrical connections for proper read. For electric I would be inclined to go at least AutoGauge (AutoMeter's lower priced line). But I prefer Mech.
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From: Hewitt, Minnesota
After reading this thread I have to comment that if you realy had no oil pressure your engine would not survive long enough to get warm. Of course on the other hand it would get warm real fast. My father had the exact same problem you describe with a 350 Chevy motor. Turned out to be the oil sensor.
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So i put in a oil presure gauge and change the oil with 15-40 and new filter. At idle it runs 2-5 psi and at driving around 1-2100 rpm its gets to about 11-13 psi. So what now? I was thinkin about dropin the pan and checking the screen if that doesnt work im gonna put a new pump on. If that doesnt work who wants to buy it in the ohio area for a 1000 bucks.
Post Fiend
Joined: Jan 2000
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From: Metro Detroit (Redford)
I would suggest if you are dropping the pan, just put a new oil pump on it. Someone said the oil pumps on these engines wear a lot. Whether or not that is true, the oil pump does get unfiltered oil and so would be subject to more wear than other engine components downstream of the filter. I had my pan off and the screen cleaned and wish I had had the pump changed, though my pressure problem is not nearly as drastic as yours. Once the new pump is on, you probably could run 10w30. Murrays (if you have in your area) sells HDEO Motorcraft 10w30 in quarts.
Another possibility is the oil pump relief valve is stuck open and bleeding off most of the pressure. I don't know how many miles on your engine, but probably a lot for an '88. Does the engine run pretty good otherwise? That is, the bearings are not so loose and knocking around that the oil pressure may be bleeding out the mains, no? I suppose its a c-r-a-p shoot to put a new pump, but to me seems the most likely fix that will work or help.
Another possibility is the oil pump relief valve is stuck open and bleeding off most of the pressure. I don't know how many miles on your engine, but probably a lot for an '88. Does the engine run pretty good otherwise? That is, the bearings are not so loose and knocking around that the oil pressure may be bleeding out the mains, no? I suppose its a c-r-a-p shoot to put a new pump, but to me seems the most likely fix that will work or help.
Post Fiend
Joined: May 2004
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From: Lakewood, Ohio
get regular oil pump, new screen and one piece felpro gasket.
go to oil section and you will find many posts on removing pan.
i have done this so ask me and i will help you through it.
i got a spray can cap full of the sludge in the pickup screen!
that 15-40 oil did not help your problem.
go to oil section and you will find many posts on removing pan.
i have done this so ask me and i will help you through it.
i got a spray can cap full of the sludge in the pickup screen!
that 15-40 oil did not help your problem.