I have a 1991 motorhome with a Ford 460 EFI engine. When the engine is started, the oil pressure takes as long as 60 seconds to reach it's normal level. The longer the engine has been off, the longer it takes to reach it's normal level, which is about 55 psi at 3,000 rpm and about 35 psi at idle. It is as if all the oil is draining out of the all the oil galleys and the oil pump has to refill everything before the oil pressure is achieved. During this time, the hydraulic lifters are noisey. The engine has about 68,000 miles. The problem seems to be getting worse. Any one have any ideas?

Thanks,

 

What kind of oil filter are you useing?

Some oil filters (Fram Espically) have a problem with oil draining out of the filter and back into the pan and then not wanting to refill right away again.

It could also be a screwed up pressure relief valve, or a oil pump getting weak.

What I would do is switch to a thicker oil....like 20W50 or so. I

later,
Dustin

 

Since its a M/H with a 460, probably got a rear sump oil pan & would need a long pick up tube for the oil pump.
That long pick up tube can crack right around the flange weld where it bolts to the pump & causes it to be slow building oil presure at start up.
A cheap test just to see if thats what it is, would be way over fill the engine during an oil change, enough extra oil added to reach the level of where that tube bolts to the pump. Start the engine & run just long enough to see what the presure gauge does. If oil presure goes up when the engine is started you'll know that is the problem .
If that tube is cracked, its sucking air on start up & not building oil presure.
When you do the over fill test, that crack in the tube will be under oil & cant draw in air.

After the test, get a good CLEAN pan to drain the engine oil into so it can be used after the repair is made.
I've been through this reason I know it will work.
Neil