dropping oil presure

[norm1896]

could anyone tell me what all could cause oil presure to drop after engine warms up,im going to pull it out and hate to miss anything.87 f150 w/302 about 138000 miles

 

[d-kuzmen]

Weak pump, bearing clearences, pluged return ports. When the engine is cold the oil is thick but as it warms it gets thinner and if theres any excessive bearing clearences and such the psi will drop down.

 

[blacksnapon]

 

[TheRoadVirus]

Oil psi generally drops after the engine warms up.. The oil is thicker 'til it heats up.

 

[norm1896]

should i replace the cam bearings too?

 

[Fellro]

How are you reading the oil pressure? If you are looking at the stock gauge, you need to verify it by hooking up a good gauge, the factory unit is not a good tool, as accuracy can be a real problem. Before you get too excited, make sure it actually is what it seems. It is normal to drop some from the cold reading once warmed up.

 

[blacksnapon]

should i replace the cam bearings too?

If you have the means, Yes, definately. Any of the bearings being worn can cause oil pressure issues.

 

[norm1896]

the stock gauge fluchuates,but after truck runs a while goes all the way to the bad side and engine begins ticking.

 

[Fellro]

That does sound like low oil pressure.. My 88 drops down to zero, but the engine doesn't sound like it has no pressure. The gauge waves wildly too. I haven't taken the time to hook up a good gauge yet, but no ticking from this engine.

 

[norm1896]

ok thanks, im going to take it out and tear it down and take a look.ive tried the merical in a can stuff but never have had much luck with that kind of stuff

 

[msb71]

My 78 w/ 351M read just like what fellro was saying good pressure on start up , then low at idle, half at 60 MPH on highway, needle went all over the board.

Mike

 

[norm1896]

i have a79 with the 351m ive had nothing but bad luck with,if i can get this 87 half rite im going to try to get that thing going,last time i had it running i could rev it up and throw a three foot flame outa both exhaust pipes,things a mess.