bad oil pressure...
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New User
Joined: May 2004
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From: Wichita
bad oil pressure...
I have a 81' ford f100, everything works fine except the oil pressure,
the oil pressure builds up over night but when i get in it to go to school in the morning i get about 1/4 mile from my house and the pressure drops to low, I know the problem isn't with the gage because in the morning its 1/4 past L then
it drops and sits on L until i get to school.
After I got the front main seal replaced so it would quit leaking oil and I thought that would fix the low oil pressure but it didn't,
I filled it to the full mark on the dipstick so I know its not just low on oil.
Does anyone have any ideas on what could be wrong?
I have to get this fixed soon, I cant afford $50 in gas every week just going
back and forth to school.
Please help..
the oil pressure builds up over night but when i get in it to go to school in the morning i get about 1/4 mile from my house and the pressure drops to low, I know the problem isn't with the gage because in the morning its 1/4 past L then
it drops and sits on L until i get to school.
After I got the front main seal replaced so it would quit leaking oil and I thought that would fix the low oil pressure but it didn't,
I filled it to the full mark on the dipstick so I know its not just low on oil.
Does anyone have any ideas on what could be wrong?
I have to get this fixed soon, I cant afford $50 in gas every week just going
back and forth to school.
Please help..
Posting Guru
Joined: Apr 2003
Posts: 1,153
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From: Venezuela
1° confirm low oil press using an external mechanical gauge.
2° if there is a real low oil pressure (Less than 10 psi at idle) replace oil filter and oil, be sure use proper oil type like 10W-30 or 15W-40
3° Make a compression test looking for readings over 100 psi + or - 5 psi, maybe your engine has high milleage....
4° Remove distributor and have a look at the tip of Hex rod wich moves oil pump, exesive wear? then replace it.
5° remove oil pan and check oil pump and verify one Rod bearing and one Main bearing for wear (Using plastigauge)
2° if there is a real low oil pressure (Less than 10 psi at idle) replace oil filter and oil, be sure use proper oil type like 10W-30 or 15W-40
3° Make a compression test looking for readings over 100 psi + or - 5 psi, maybe your engine has high milleage....
4° Remove distributor and have a look at the tip of Hex rod wich moves oil pump, exesive wear? then replace it.
5° remove oil pan and check oil pump and verify one Rod bearing and one Main bearing for wear (Using plastigauge)
Fleet Owner
Joined: Jan 2004
Posts: 26,007
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From: Brentwood,CA
if the engine is high mileage use 20w 50 and that should fix it or before you change the oil use some gunk engine flush you might have carbon buildup on the pickup tube which is not letting the oil enter the pump which can destroy a engine quick if you don't have any gunk engine flush use a quart of diesel fuel it will clean the engine spotless and won't harm it because diesel is a oil
Senior User
Joined: Nov 2003
Posts: 298
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From: Saint Maries Idaho
i would suggest changing the engine bearings. my 83 f150 had low oil pressure with 135000 miles on it i changed the bearings and i have high oil pressure without a full overhaul. it is pretty quick and easy just drop the oil pan and then u can get at everything fairly easy. on mine i had to lift the engine up a litttle though. before u try this i would highly suggest pressure washing the underside of your pickup first (it saves a lot of dirt in your face and engine).
the total time it took me was about 4 hours. i changed the crank bearings and rod bearings
the total time it took me was about 4 hours. i changed the crank bearings and rod bearings
FTE Leadership Emeritus
Joined: Sep 2000
Posts: 7,298
Likes: 45
From: Southern California
It's what we call an 'idiot gauge', or an idiot light with a needle. It only takes 8 psi to keep the needle above the L\ indication. You're not going to see any big difference even if the true oil pressure is 70 psi. One fair idication of good oil pressure is the lifters. If they aren't tap tap tapp'in at idle, chances are oil pressure is sufficient.
L\normal/H
I would confirm the pressure with a mechanical gauge first. Then move on to the other good advice you've been given. I would add to that, the oil pickup screen may be blocked and need to be cleaned of sludgey gunk.
L\normal/H
I would confirm the pressure with a mechanical gauge first. Then move on to the other good advice you've been given. I would add to that, the oil pickup screen may be blocked and need to be cleaned of sludgey gunk.
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New User
Joined: May 2004
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From: Wichita
Fordtruckman - How much did the crank and the rod bearings cost, and where there any seals that had to be replaced when you took off the oil pan?
horsepuller - You can probably tell i dont know a whole lot about my truck, where would the oil pickup screen be?
The only two things that i've done to my truck are, replace the alternator, change the shocks and put on a glasspack muffler.
horsepuller - You can probably tell i dont know a whole lot about my truck, where would the oil pickup screen be?
The only two things that i've done to my truck are, replace the alternator, change the shocks and put on a glasspack muffler.
FTE Leadership Emeritus
Joined: Sep 2000
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From: Southern California
Oil pickup screen is on the suction of the oil pump. It's submerged in oil. You'll have to pull the pan to inspect it.
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Posting Guru
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From: Florida Hill Country
Horsepuller, I thought those pre-86 oil gauges had "real" sending units. What about the temp gauges? I know there are a lot of guys who put a pre86 sending unit in there 87 up Broncos and pull the instrument cluster and put a jumper on the gauge where the resistor is on the oil pressure gauge. The needle the deflects normally.
There are some good suggestions on here. Especially check the distributer and change the oil and filter. Like Horsepuller said, if you had low pressure, you should be hearing lifters making noise.
There are some good suggestions on here. Especially check the distributer and change the oil and filter. Like Horsepuller said, if you had low pressure, you should be hearing lifters making noise.
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From: Venezuela
Originally Posted by rlh
...Like Horsepuller said, if you had low pressure, you should be hearing lifters making noise.
FTE Leadership Emeritus
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From: Southern California
Originally Posted by rlh
Horsepuller, I thought those pre-86 oil gauges had "real" sending units. What about the temp gauges? .....
Post Fiend
Joined: Jun 2003
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From: NE Texas
Originally Posted by ghettomonkey2003
I have to get this fixed soon, I cant afford $50 in gas every week just going
back and forth to school.
Please help..
back and forth to school.
Please help..
Just to let you know that the oil pressure problem is more than likely not the cause of the fuel consuming problem.
And welcome to FTE!
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