Hot Rods oil pressure go to 100 + psi

Well I don't know what happened but my oil pressure went from around 80 psi cold to over 100 psi. This is a 1969 440 mopar in a 1938 Plymouth coupe, with a Melling pump HV. I had not started the car in a couple mouths and when I did, it pegged the gauge to 100 + psi. This is an electric gauge so I replaced the sending unit, then the same 100+ so then I changed the oil & filter and the same 100+ psi, now the oil is running out the valve covers. I called Melling and they had no answer for me or they did not help me.
So do I just order a new pump or what ? Thanks for your time Mike

 

Hydraulic system HP = HV . Change the filter 1st if you haven’t . If you have dis***emble the pump and verify operation of RV that it is not stuck or binding in any way . If nothing toss the pump . Have you ran the engine before now with no issues ?

 

High viscosity oil / extremely cold? Just a WAG.

 

Yes I have change the filter & taken the pump apart to check the spring and slug, and I have ran the engine for years with no problems

 

The oil is 10w40 and the car sits in a heated garage

 

I had a Ford engine do that. Blew the filter right off the car. It was the check valve in the oil pump.

 

If you've changed the filter and inspected the relief (pressure regulator)valve, then before anything else I'd suggest using a mechanical gauge to verify the readings your electric is showing.

 

Got to be a bad pressure relief valve or a bad gauge. Can't think of anything else that would do that.

 

^^^
What they said. If the pressure is accurate, it's got to be the relief valve unless something REALLY strange is going on. At least the pump is external.
Was the filter ballooned? That would indicate the pressure is too high.
The only other cause would be a sudden new restriction (deadhead) in the oiling p***ages, but even then the relief valve should byp***.

 

I do not know for sure if you can spring a Electric gauge like you can't a mechanical ,
I would verify with a known good mechanical gauge ..

Curious to know what oil filter brand and Standerd, Gold , Max ect.

 

I had a Ford FE that would blow the filter apart. Stuck relief valve on the pump

 

I have just put a new mechanical gauge in and ordered a new pump

 

I’d look at the gauge first.is it mechanical. If so there maybe a piece of garbage hung up in the line. Next culprit would be the spring and pressure valve in the pump, may be hanging up. What’s the pressure when the motor is warmed up?

 

Oil pump, remove the plug and check the oil pressure relief valve and spring. It can get stuck. Access the valve on the oil pump's cover. The valve sleeve can get stuck and tough to remove. Might have to remove power steering pump to get at it. If you can't get it out you will have to take pump off.

 

The filter was OK, but I but a new one on anway.

Wix racing filter with Lucas Hot Rod 10w30 oil

 

100psi

 

@Bonehead II
I use wix race my self , The ones I have are 10 yrs old a few cases ,,
I am hearing now Issues with wix band for like last few years ..

 

I'd recommend against a high pressure pump when replacing it. High volume is nice but requires oil pan modification. I used the M-15 and had to make a slight mod as the pump is a bit deeper.

 

I'd change out the gauge itself first.

You've changed oil filter, pulled pump and relief valve and checked those, changed electric sending unit so the only thing left is the gauge itself not reading properly OR a wiring or ground problem to the gauge itself.

I'd buy a cheap mechanical gauge over the counter at the local parts store, stick it on the motor real fast and dirty, fire it up and read that gauge. IF it shows regular oil pressure then I'd just order another oil gauge to go back into the cabin and swap them out...

....

 

Did you replace the oil pump before the surge in OP or has the pump been on the motor for a while?
If the new pump and the mechanical gauge don't fix the problem, I think I would be looking for plugged oil p***ages between the pump and the gauge. I would think there would be enough places in the lower block to bleed off oil pressure, but a cam, rod or main bearing turning could cause a jump in oil pressure by blocking an oil port. Pull a valve cover and make sure oil is coming through the oil p***age to the rocker shafts, and that they are not plugged either.

 

Seems oil running out the valve covers would indicate the gauge and sender were working fine.

 

Check the PCV valve is working correctly. The following info is from the googley machine.....

High top-end oil pressure with leaks often stems from a clogged or faulty PCV valve causing crankcase pressure buildup. Inspect the valve cover gasket for damage or wear, as leaks commonly occur there. Ensure the PCV system is clear and functioning to regulate pressure.

 

Its too late I have the new pump, but its HV and I have a 6 qt pan

 

OK...Thanks

 

My bad man, I had flathead stuck in my head for some reason. I just went back and read post one. Duh.