C2 Oil Pressure Reading High

[Donald T.]

My 65 L79 has been reading high oil pressure since I acquired it. The motor was rebuilt before I owned it, and the rebuilder installed a high volume oil pump. I just replaced the oil pump with a standard unit and the reading is lower, but still over 60 lbs. at idle. The archives suggest using a test gauge to verify the reading. I checked the Internet and the only one I found cost $125. Is there a cheaper method for checking oil pressure? If the gauge is found to be faulty, how can it be recalibrated? Is there anything else I should look for that would cause the high reading? Any advice would be greatly appreciated.

Thanks!

[Dick W.]

Re: C2 Oil Pressure Reading High

Go to one of your local auto parts stores and purchase a mechanical oil pressure guage. Connect it to your engine and verify the reading. If your guage is faulty, there are several vendors that specialize in repair and restoration of insturments. I would almost be certain that your guage is out of calibration.

[Donald T.]

I'll try that. Thanks again! *NM*

[Tracy C.]

Re: C2 Oil Pressure Reading High

Don,

Before you buy one like Dick suggested, see if they have one you can "rent". This is usally just a deposit that is refunded upon the return of the tool.

Many parts houses are doing this now. Call around first.

tc

[Loren L.]

Go sit in a C4 or later - start it

and watch the oil pressure gauge - now, relax and realize that you have a car that does not depreciate, and drive the snot out of it.......

[Mike McKown]

Another thing

If your block has an oil galley plug at the front of the block, you can plumb in your test guage here much easier than messing with the port at the back where your oil sender is located. Keep in mind that reading from the front of the block will show maybe five pounds less at idle than what it will read at the back of the block due to pressure loss through the cam and valve train.

[Chuck S.]

Re: Another thing

Actually, Mike, I don't think I would mess with any of those small pipe plugs on the engine block.

My experience from rebuilding my own engine is that those small pipe plugs are dang near impossible to get out sometimes...I don't know if they screwed them in deep while the block was still warm or what. My rebuilder advised against removing them. If that front plug is as hard to get out as the rear plugs, Don will end up with a rounded, buggered plug that still won't come out.

[Brian Monticello]

Re: C2 Oil Pressure Reading High

Don,
Before I rebuilt my engine I had the inverse problem. My in-dash gauge was telling me I had 5 lbs at idle and 15 at 4000 RPM. I started a fake company and ordered a nice 0-100 # gauge from grainger + a 1' hose. Went to the HW store and picked up some fittings. Total cost = $35.

I removed the line at the gauge and connected the gauge from grainger -- 20lbs at idle and 40 @ 4000.

I still have the bad gauge in the dash with a fresh engine and I have that same grainger gauge connected to the front of the block at the location mentioned in the thread. The melling m55 (standard) and .003 main and .0025 journal clearance on the crank generates about 60 at cold start and about 40 at hot idle (at the FRONT of the Block)........in dash gauge still reads 15.

Brian

[Craig S.]

Re: Another thing

Chuck - I always take mine out in a rebuild and clean the oil galleys with bore brushes, you need a square drive tool, I crafted one from a socket extension shaft. I also apply heat via an oxy/acet by lightly fanning the area of the block around the plug, with the flame set on the cool side. This basically works every time, and the plugs come right out. This is not something I would sugget though with the engine still in the car......Craig

[Ralph E.]

Re: C2 Oil Pressure Reading High

Don,
I had this exact same problem last fall.
Run the engine to normal operating temperature. Shut it down. Wait 5 minutes. Restart engine. Chances are the oil pressure will not be as high. What is happening is the oil in the pressure gauge is not the thin heated oil that is in the engine. Also, you may need an oil change.
Please give this a try. Good Luck
Post results.

Ralph #37280

[Donald T.]

Re: C2 Oil Pressure Reading High

Thanks Ralph. Yes, it does come down a little when the engine warms up. I just replaced the oil pump, pan, and filter, so it has fresh oil. With the engine at operating temperature the gauge will come down to just below 60. Increasing the RPM sends it right off the scale. I think I'll just wait until the first snowfall here in Indiana, and send in the gauge for a rebuild.

Appreciate everyone's advice on the topic!