Excessive oil pressure problem

I changed the oil filter in my BN1 and noticed how it looked like it hadn't been done in years and the oil was like black paint. I was correct after talking to the previous owner he said he didn't have it changed since it came to Canada 25 years ago. So I pulled the valve cover and the rocker arm assembly . Cleaned it and also the crap that was under the valve train. Then removed the oil pan and pickup screen and cleaned it. Put in a new filter, added oil. cranked the engine over till there was pressure then started it. Now it goes to just past 100 lbs!!!!! I know the passages are clear and pulled the relief valve under the filter to check for sticking. It was ok. Anyone have an idea as to why the pressure is high?

Re: high oil pressure problem

Sounds like the oil relief valve is stuck. It's located on the side of the engine. It's purpose is to bypass excessive oil pressure. It is a spring loaded conical shaped valve. Needs to be removed and the passage cleaned out.

Re: high oil pressure problem

Is the gauge accurate?

Bruce

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Put in a new filter, added oil. cranked the engine over till there was pressure then started it. Now it goes to just past 100 lbs!!!!! I know the passages are clear and pulled the relief valve under the filter to check for sticking. It was ok. Anyone have an idea as to why the pressure is high?

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I wonder if the outlet to the relief valve is plugged? Why not pull the valve, remove the rotor or plug leads and crank it over to see if any oil makes it out?

It sure is nice having the Forum back!

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Put in a new filter, added oil. cranked the engine over till there was pressure then started it. Now it goes to just past 100 lbs!!!!! I know the passages are clear and pulled the relief valve under the filter to check for sticking. It was ok. Anyone have an idea as to why the pressure is high?

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What was the pressure before your changes?
The possibilities are:
1- Someone has changed or shimmed the relief valve spring for more tension.
2- The spring is binding inside the relief valve plunger.
3- Related - the plunger is not moving back far enough to uncover the relief port, or the wrong plunger is installed. The Fours & the Sixes use a different plunger.
4- The plunger is still binding, although you checked it.
5- The passage from the pump to the relief valve is restricted/plugged.
6- The passage from the relief valve port back to the sump is restricted/plugged.

See attached pic of the oil flow.

A remote possibility is that the oil pressure gage itself is sticking at full pressure. My gage does this occasionaly. Simply moving the hard line on the back of the gage very slightly unsticks it.
D

you know for some reason I do not remember the oil pressure before I discovered the plugged oil filter and did all that cleaning. I did remove the relief valve plunger and noticed that the edge beside the front was scored .Probably from being forced open from the plugged filter for all that time. The pressure reads O before I start the engine then pegs to the 100 mark. . I will try removing the valve and turn over the engine briefly , to see if any oil comes out the plug hole.

The oil pressure gage take off is down stream from the relief valve & the filter. A plugged filter would have caused the gage to read very low. If I could get the above mentioned pic to you, you would be able to see immediately how it works.
D

Dave, I added my address to my profile so you can send the pic now.
Thks
Dennis

Dennis,

It's on the way.
D

Tonight I checked the oil pressure with a new oil guage. It went high the same as the in-dash guage. So I removed the valve cover and the small oil pipe along with the fitting that screws into the top of the head leaving an opening about 1/2 " Dia. Then I removed the coil lead and turned over the engine with the starter. I noticed that the pressure went to 55 and there was a considerable amount of oil being forced out the hole in the head ! LOL!!
So my next thought is the valve train is plugged and not allowing the oil out the rockers. I'm pulling the valve train this weekend , dissassembling it and try the pressure again.

I don't think that the rocker arms allow enough oil flow to seriously reduce pressure. With good tight rocker to shaft fits, there should only be small dribbles of oil coming out of the rocker to shaft joints. If there is more, it will flood the valve guides & cause problems. I'm not surprised that you got lower pressure with the hole wide open. Way more than normal flow. There is still a problem with the presure regulator.
D

ok then I will look again at the regulator. Perhaps someone stretched the spring to compensate for the plugged filter lowering the pressure. Any idea as to the proper length of spring ? I could purchase a new one with tip!

well I pulled the valve train and disassembled it. Luckily I did that because I found some rocker oil holes where plugged including some that feeds the pushrods and the rocker tube had some crap in it also. Reassembled everything, reset the lifters and tried the oil pressure again. Still went past 100 lbs. So I pulled the oil pressure spring and measured it - 2-3/4" long. Put it the vise and compressed it then touched the flame of a propane torch in the middle to relax some coils. Tried it and the pressure went down. Now I reset the idle to just over 500 rpm and trial and errored the spring lenght to 1-7/8". Now the hot oil pressure is just over 50 lbs. Someone had stretched the spring to compensate for the plugged oil filter.
Problem solved!!!!!!!

Excellent! You may want to get a new spring now, ‘cause your spring may be sprung from the heat.

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Tried it and the pressure went down. Now I reset the idle to just over 500 rpm and trial and errored the spring lenght to 1-7/8". Now the hot oil pressure is just over 50 lbs. Someone had stretched the spring to compensate for the plugged oil filter.
Problem solved!!!!!!!

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Excellent. Your explanation is very likely why someone stretched the spring. As Greg said, not sure if I would trust the spring for the long haul. You could get a new spring, Moss #329-045 for about $5. Might be a good idea.
D

ya I will get a new spring. Just curious about what pressure this engine should be at say around 3000 rpm. Any books I have here only relate to idle pressures @ 50-55 psi.

The pressure "should" be around 60 psi max at any rpm above 2000 rpm. This would be the maximum pressure that the regulator allows, hot OR cold. It would likely be around 30 to 40 at HOT idle. Hot meaning that the engine has been driven for 30 minutes or more. Cold idle pressures might be as high as 55. Excess pressure just creates more leaks & oil consumption & puts unnecessary strain on the pump drive.
D

Rusty--

I'd be interested knowing what is your experience after you install the new spring and the source of it. I recently shimmed the spring in my car using a hex nut inside the plunger that was about .25 thick and it increased pressure about 10 psi across the board. But pressure still varies quite a bit (for example, it is about 45 psi at 2500 rpm's but goes up to 55 at 3000 rpm's) which makes me suspect that the spring has just seen better days.

Please let us know the final outcome.