what could be causing this?
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Senior User
Joined: Oct 2003
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From: Southeastern N.C.
what could be causing this?
My 88 300 6 cylinder 4x4 holds about 55-60 psi oil pressure cold and at idle 10 mi down the road the pressure drops the further I drive until it gets down to about 5 psi at idle.I have changed the oil,even put a second filter after the oil change."switched from fram to motorcraft and gained 10 psi at idle".Any ideas what the problem could be?I would think if it was the oil pump the pressure would be low all the time."Maybe the screen?"
I have allways changed the oil regularly and allways used a good brand name oil to prevent problems like this.Any idea what coud be the culprit please let me know!
herothc
I have allways changed the oil regularly and allways used a good brand name oil to prevent problems like this.Any idea what coud be the culprit please let me know!
herothc
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Joined: Apr 2003
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From: Citrus County, Florida
Oil viscosity. The warmer the oil gets the thinner it gets also. What size oil are you using? I had to go to 15/40 rotella to keep the oil pressure up and eliminate lifter noise when the engine was warm.
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Senior User
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From: Southeastern N.C.
I`m useing 10w/30 with oil treatment.After warming up it holds mabey 10/12 at 1000/2000 rpms.And it`s got 91,000 miles on her.Mabey more,it was suposeovly rebuilt according to first owner.I think I`m going to try a good bit heavier oil to try and keep oil pressure,what could it hurt? Galaxiedan,was your pressure running this low?As Krocklein say`s I`m just trying to learn what I don`t know!Please reply.herothc
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Senior User
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From: Southeastern N.C.
I`m using a heavier oil now,20w50,just to see what it would do. It held the high pressure a little longer,after warm it idles at about 5 psi and 20 psi at 2000 rpm.Any other ideas what else I can do to bring the oil pressure up?
Cargo Master
Joined: Oct 2003
Posts: 2,833
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From: Jefferson, Iowa
Check bearing clearances, maybe main bearings might be the problem. What brand of oil are you using, i have seen pennzoil to plug up several componants in the iling system, which would get plugged from the wax in the pennzoil. Try getting a good engine flush and flush the engine out. Otherwise i would try getting a melling high volume oil pump, pretty cheap compared to an engine.
Senior User
Joined: Apr 2003
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From: Citrus County, Florida
I never had a gauge that told actual pressure number in lbs but my oil pressure will barely get into the normal range and I will get terrible lifter noise if I use 10w 30. Once I put in 15w40 the pressure stays almost in the middle of the gauge and the motor is quiet.
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From: Long Island
Hey herothc.
do you have lifter noise at idle, if you don't, you have "enough" oil pressure to get by, if you do and it goes away with a rise in rpm then you lack oil flow.
If you don't know what lifter noise on the inline 6 is, just pull the oil filter and put a new on, you will hear the lifters clack untill the system is primed and it will go away(assuming it isn't clacking now"
One mans "rebuild" is another mans valve job, who knows what was done.
The rule of thumb for 10 lbs pressure per thousand rpm was first proposed by Smokey Yunick, for nascar racing engines in rase trim. It does not hold for stock vehicle engines. Look at fords specs for the oil sending unit, 6 lbs pressure it registers O.K.
The things you have to worry about is that the lifters are pressurized and you are maintaining adequate oil film on the mains, most of the rest of the engine is splash lubricated.
If the engine is running fine, no noises etc., I would just run it, unless you're into doing a rebuld
do you have lifter noise at idle, if you don't, you have "enough" oil pressure to get by, if you do and it goes away with a rise in rpm then you lack oil flow.
If you don't know what lifter noise on the inline 6 is, just pull the oil filter and put a new on, you will hear the lifters clack untill the system is primed and it will go away(assuming it isn't clacking now"
One mans "rebuild" is another mans valve job, who knows what was done.
The rule of thumb for 10 lbs pressure per thousand rpm was first proposed by Smokey Yunick, for nascar racing engines in rase trim. It does not hold for stock vehicle engines. Look at fords specs for the oil sending unit, 6 lbs pressure it registers O.K.
The things you have to worry about is that the lifters are pressurized and you are maintaining adequate oil film on the mains, most of the rest of the engine is splash lubricated.
If the engine is running fine, no noises etc., I would just run it, unless you're into doing a rebuld
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Joined: Oct 2003
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From: IL
Have to say i think that it could b the oil pressure sending unit or something in the gage or arround those parts....I rebuilt a inline 6 and was going through almost 2 Qts every 3 thousands miles and always had low oil pressure on the gage...the oil sending unit was wet and leaking oil ....changed and all well...
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