high oil pressure

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Sep 6, 2011 | 02:05 PM

390injun

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high oil pressure

Hi I got an issue that seems to putting wut little knowledge i have about trouble shooting lol, I currently have a 73 F100 pick up with a 390,that i put alot of time and money in to the motor,as of resently my oil pressure gauges has been reading high but after a bit it will drop to normal,this has been going on for a bit with not much concern as it has done it for a little while.long story short i fired it up the other day let it warm up not 1min into it i hear a pop lost my oil pressure shut the truck off looked underneath and a river of oil flowing down my driveway,i pulled the filter off and seen the seal had blown off seat,so changed filter dumped cleaning stuff in motor filled it back up started it ran fine,pressure a little high but dropped off like it did b4,fired it up the next day to get the same resaults.I cant afford an xpensive motor job and in hopes that some1 could shin some light on my poor 390 issue,i dont recall these motors having pressure releif valves in them but not wondering if my pump isnt pumping out more then it should be? Thanx for reading my story and in hopes that some one can help me

Sep 6, 2011 | 02:35 PM

DrainBramage

Senior User

Joined: Jul 2011

Posts: 215

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From: California

Filter should have an internal relief valve... what brand/part number filters are you using? What were your bearing clearances when you built the motor? What brand/model oil pump did you use when you did the rebuild? HV, HP, etc...

Sep 6, 2011 | 03:03 PM

Argess

Laughing Gas

Joined: Aug 2008

Posts: 840

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First, can you give us actual pressure numbers in psi?

Most FEs will show a drop in oil pressure once it warms up, so that part is normal.

Having pressure so high it blows the oil filter o-ring is not normal. The most likely problem is the relief valve inside the oil pump is stuck shut. When this happens, the oil pressure will get extremely high, especially when the engine is first started and the oil is cold and thick.

The bypass valve in the filter is not an issue here. It merely opens if the pressure into the filter greatly exceeds the pressure out of the filter. Typically, that valve would open if the filter was clogged and thus the engine would be saved from self-destruction due to lack of oil.

The good news is that oil pumps are very cheap. And you'll need a pan gasket. The bad news is it can take some time to remove an oil pan depending on whether there is a piece of the frame in the way, and what type of gasket sealant was used to install the oil pan.

Sep 6, 2011 | 05:22 PM

390injun

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Hi the motor is original all i did after I bought it was do the top end,and I have been using fram filters for ever in all my vehicles,exact pressure I do not have,but to be popping the o-rong off the filter has to be high and i had replaces the filter after the first time it popped,If its just the pump itself thats a releif as I have not yet had issues with the motor up till lately.And as i have read in different forums trying to find a salution it almost seems to be going back to the pump in general.And there is a cross member in the way and its looking like a motor removal unless i can jack it up high enuf to clear it.Thanx for the responces it most definately helped

Sep 6, 2011 | 10:30 PM

orich

Lead Driver

Joined: Aug 2003

Posts: 7,592

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From: **** hole San Jose ca.

Yup oil pump. My brother had that something happen to his 70 c/s 360 motor. But he would change oil around 6000 miles like the glove box manual said to do. Then maybe about a yr of having the truck this problem started. The fix replace the oil pump. Don't remember what filter he used. You can replace the oil pump with out pulling the motor you just have to take your time be careful not to raise it up to high so you don't bend carb or tranny linkage, gas line fan shroud stuff like that rad-hoses. But I've found it easier to also pull the distributor when installing the oil drive shaft. The washer on the drive rod goes up only. I've had these damn thing slide down the shaft while pulling the dist. out so I put JB weld epoxy to fix it in place. Been doing it like this for 30 yrs and on every fe I work on. I'd Put in a new oil pump drive rod while your at it. You'll have to turn the motor so the counter weights are up at there highest to slid the pan out once the oil pump is removed, with some trucks. But if you have a 4x4 high boy the pan comes right off no cross member in the way. my 2cents
orich

Sep 6, 2011 | 11:25 PM

390injun

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Thanx Orich for the input that will help for sure,i was hoping that i didnt have to pull the motor and im sure if carefull enough it should go with out a hitch lmao who m i kidding lol.Thanx all for your help and input it is most deffinatly appreciated.

Sep 7, 2011 | 06:32 AM

gfw1985

Cranky Old Guy

Joined: Mar 2008

Posts: 3,562

Likes: 6

From: Raphine, Virginia

Go back to a Motorcraft or Pure One filter. Stories abound on bad Fram filters and I personally had the side bust out on one. Filter could have been too loose or too tight or the other things mentioned. Still, Fram will never be on another vehicle of mine.