oil pressure gauge problem

[Aaron D]

Hello,
I am new to this forum and I am hoping that someone can help diagnose the source of a problem that I am having with my bone stock '63 327/340 roadster. This afternoon I just finished installing a new engine wiring harness and a new dash wiring harness. Everything went smoothly except now the mechanical oil pressure gauge is reading way too high. Prior to disassembly of the dash the oil pressure gauge would read approximately 18-20 psi at idle and appx. 40-45 psi while cruising. Now the gauge reads 30psi at idle and 60+psi while cruising. Absolutely nothing was done to either the engine or the gauge. I could see how a new high volume oil pump might give these symptoms, but as the engine was left absolutely untouched I assume that the problem lies with either the gauge itself or the line. Any ideas?

[Mac Peppers]

Re: oil pressure gauge problem

sounds like the needle has moved on the needle shaft. i'd get an aftermarket gauge and confirm the actual oil pressure, then pull the needle off and reposition it correctly.

[Aaron D]

Re: oil pressure gauge problem

Thanks Mac. I'm going to get another gauge this afternoon and check it out. I don't think that the needle is the problem as it returns to zero psi once the engine has been shut off. If the needle had been knocked out of position I assume that the gauge would read 20 or 30 psi with the engine off, no?

[Aaron D]

Re: oil pressure gauge problem

Well, now I am worried. I hooked up an auxiliary oil pressure gauge and it reads the same pressure as the stock gauge. I am stumped. Anybody?

[Mike McKown]

Re: oil pressure gauge problem

If I assume everything is the way you present it (and I don't doubt it for a minute) I'll speculate the oil pump relief valve is stuck shut.

I'd have no idea what else it could be. The only other way to boost the pressure is to increase the oil viscocity or tighten the bearing clearances. You've indicated you've done neither.

[Paul Reynolds]

Re: oil pressure gauge problem

Could be that when you took the engine out of the car, some crud drained out of the oil gauge line and now it's reading correctly. It may have been clogged up for years before giving you the lower readings.