LOW OIL PRESSURE

[bullitt77]

hi

my oil pressure is 45 psi and only 22 when hot .... so not very good

i 've change my oil pump ( and the pick up ) ... nothing change

i was thinking about main bearing failure ?! what do you think ?

is it possbile to change main bearing without put out the crankshaft?

it's a 351 W engine

thanks

 

[rbohm]

22psi hot at what rpm??

 

[mustangdave]

Your pressure is fine.

 

[351carlo]

22 PSI isn't a big deal. I like 30-35 @ 1000 RPM and then another 10psi per 1000 RPM.

You should be fine so long as it doesn't go below 20. What weight oil are you running?

 

[Blue Oval Man]

Pressure sounds OK, so far! Something to check would be the cam bearings. If they have to much clearance the pressure will definitely fall off as time goes by. If you have had a rebuild recently, did they change the cam bearings? Some shops just go with what's there figuring if they were OK before, they will be OK after. This is one of those, been there, happened to me deals.
David.

 

[bullitt77]

hi everybody !

first : thanks for all your answer

i 've 22 psi at 3000rpm engine hot , my oil is 20w50 ... so you could see that's not very good

i don't know if a previous owner change the camshaft , neither the cam bearing ,

so you think about checking cam bearing and crankshaft bearing ?

 

[mustangdave]

Yes, too much clearance at either bearing point will cause low pressure. I thought you had 22 p.s.i. at idle. Usually, too much bearing clearance will cause severe low pressure at idle when hot and it will climb with r.p.m. My old 302 had 0 pressure hot at idle and 30 at higher r.p.m. : never did blow though.

 

[bullitt77]

in fact when the engine is cool i've 54 psi at idle and at 3000 rpm , it doesn't move

then when hot the oil pressure is 22 psi , at idle and at 3000 rpm , she doesn't move with the rpm ???

i 've a mechanical oil pressure gauge : an autometer

what do you think of that?

 

[mustangdave]

Sounds like a little wear in the baerings but not enuff to tear the engine apart for.

 

[Max Power]

I am sure it is all your bearing clearances. The only cure is a complete rebuild, if you want to do it right. You have enough oil pressure for now.

 

[rbohm]

you have excessive bearing clearances, though as stated not enough to cause major problems yet. you can shim the oil pressure relief valve to increase pressure, just dont go crazy.

 

[BB1966]

Good thing about Ford they will go a LONG way on ZERO op!!!!!!!

 

[bullitt77]

thnaks for all this answer !

so if i translate correctly your answer , there is no emergency ?!

good news !

where is the oil pressure relief valve? is hard to change ?

regards

guillaume