High Oil Pressure Reading?

[mbplace]

2f in a 77 fj40 - question about oil pressure readings. Just got the vehicle serviced/oil changed and the oil pressure seemed fine and steady about midway on the OEM style gauge until the other day — now it’s showing as pegged at idle.

Hooked up a mechanical gauge and it reads 55/60 cold idle and I’m hearing a slight knock. Any cause for concern? What are the limits on these gauges and could it just be a bad sending unit?

Searched the forums and really only found info on the low pressure, not so much on high pressure. Want to take it back to the shop but concerned about the 5 mile drive

 

[Grayscale]

Try a different oil filter. Perhaps the internal pressure relief valve is faulty, in the new filter?

Where is the oil pressure sending unit on a '77? Check for anything not normal there.

 

[charliemeyer007]

I'd be concerned with the knock. Gauges especially electronic ones can lie. Oil pressure is too important to risk, so I put in a direct read unit.

Pull the valve cover and verify you have oil flow up top at idle.

 

[Pighead]

2f in a 77 fj40 - question about oil pressure readings. Just got the vehicle serviced/oil changed and the oil pressure seemed fine and steady about midway on the OEM style gauge until the other day — now it’s showing as pegged at idle.

Hooked up a mechanical gauge and it reads 55/60 cold idle and I’m hearing a slight knock. Any cause for concern? What are the limits on these gauges and could it just be a bad sending unit?

Searched the forums and really only found info on the low pressure, not so much on high pressure. Want to take it back to the shop but concerned about the 5 mile drive

View attachment 3694144

Not too high. My aftermarket mechanical gauge shows 72 PSI on startup. I think that's about where the FSM says the oilpressure relief valve should be set.
Check your oilpressure gauge wire to see if it's grounding somewhere.
Did you change weight of oil?

 

[pb4ugo]

60 psi shouldn't peg the gauge. See if the wire is grounding at the sender or anywhere along the wire. If it's not, then I would suspect the sender.

 

[mrboatman]

Here’s where my gauge sits and the manual gauge is pretty pegged at 80psi