Oil Pressure Question

[SkipBurney]

I have a strange oil pressure question. My oil pressure usually runs around 40 psi but yesterday it began to drop down to 10 or15 lbs. I was near the house so I stopped for fuel and when I got back in the truck its back to 40 psi. Today its back down to 10 or 15. Is there a relief valve that could be sticking open or something and how can I check it out.

 

[IDIBRONCO]

Yes there is. First, are you using a good aftermarket gauge?

 

[SkipBurney]

Stewart Warner

 

[SkipBurney]

It must have been something in the bypass valve I went out and started to pull it into the shop and lo and behold it has 40 lbs at a hot idle. I drove it around for a while and it has a solid 40 lbs at idle or cruising down the road

 

[IDIBRONCO]

So the oil pressure never changes? It sounds like it's your gauge or sender (if it's an electric gauge) to me. I don't think that there's any way that you could have 40 PSI at a hot idle.

 

[SkipBurney]

Its a mechanical gauge and it may fluctuate 5 lbs or so. I even checked it against a Rochester gauge I had left over from restoring my J-3 Cub and they both read the same. I`m thinking the relief valve hung partially open and was dumping oil back and when it cooled down it reset

 

[riphip]

Should not read higher than 20 at idle. You may have a blockage or problem restrictor valve. What does it read driving, say 35-45 mph.

 

[SkipBurney]

It reads 40 psi going down the road maybe 35 at a hot idle. I has been this way since I got the truck a few years ago. The dash gauge reads right in the middle of the sweep its on the R in normal

 

[Macrobb]

The dash gauge is just a switch; useless. It only reads ">7 psi" or off.

Otherwise, what I usually expect to see is ~12-18 psi at hot idle, ~25-40 at 2000 RPM, and a max of perhaps 55 when cold at high RPM.
In your case, if it's measuring higher than that... wow, that's good I guess.

 

[SkipBurney]

Yeah that’s why the first thing I did was to install a gauge.