High Oil Pressure

[Don]

Just had my engine rebuilt. It's a 230 in3 flathead, originally from an M-37.

My problem is the oil pressure is too high. It pegged the 80 psi gauge at startup. Also had problems with leaks at the filter, hoses and gauge.

I checked that the relief valve was properly installed. Then I checked that the oil filter passages were clear, and even bypassed it with hoses. I replaced the relief valve spring but got no change. I finally cut down the spring by trial and error until I got 35 psi at idle.

Has anyone had a similar problem or have an idea as to what is causing this?

[fred ransome]

Just a thought. I see the parts catalog (for WWII engine) lists three different relief valve springs. I assume the heavier spring is used to compensate for low oil pressure in a worn engine. You may have had the heavier spring in your engine prior to rebuild. With a newly rebuilt and tight engine maybe you need the lighter spring.

[motto]

There is something that doesn't make sense here. If an original oil filter is bypassed with unrestricted oil lines the oil pressure should dramatically reduce to a very low figure as the restriction is within the filter. By removing the filter from the system with a bypass line the output from the pump should be dumped straight back into the oil pan. From memory it is returned through the same orifice as the pressure relief valve dumps its excess oil. If that orifice is partially blocked it would have the results you describe.
Another possibility is that your indication is faulty.
The TM takes excess oil pressure seriously and calls for immediate investigation as it may indicate a blockage.
The ultimate test is to remove the oil pan and pressurise the system with an external pump and see where it does or doesn't come out.

David

[tankdriver]

Mine was running high oil pressure and some one had put a spacer in the plug to press on the relief harder than it should be. Puled it out, and pressure was fine.

[Don]

Thank you all for the replies.

I'll check to see if I can find a lighter spring.

The oil from the filter back to the pan is controlled by the relief valve, so the pressure wasn't lowered when I bypassed the filter.

I did check the passage through the relief valve and into the sump was clear. However, I found a drawing of the valve on the web that shows there are 2 holes that dump to the pan. I'll go back and make sure the other one is clear, too. Also, I'll try another gauge to check my original is ok.

Besides my M-37 engine, I've got 2 other relief valves; 1 from a dodge truck and 1 from a Plymouth car. All 3 are slightly different shapes and lengths. The one in my M-37 engine matches the one in the M-37 maintenance manual.

I'll let you know how it turns out.

[motto]

I have a T245 engine that I am putting together at the moment and went out to check on a couple of things. There is no restriction in the relief valve for oil returning from the filter to the sump. It certainly does not have to unseat the relief valve to do so. The relief valve poppet is 1/2" diameter and 1-7/16" long with a hole drilled up the middle that intersects with a hole drilled cross ways. It has three lands roughly 1/4" wide, one at each end and one to one side of the half way point.
The poppet would have to be put in the right way around to function correctly as it is not symmetrical. I believe the correct way is with the blank end inwards and the drilled end outwards towards the spring.
I tend to think that you're problem is related to the relief valve installation/selection.

David

[Don]

I'll check again the orientation of the relief valve plunger, and also if any shims have been installed between the plug and the spring.

Here is the description of the relief valve from the T-245 engine manual:

"Engine oil pressure is controlled by a relief valve mounted on the left side of the engine below the starter and consists of a plunger type valve, spring, gasket and plug. The relief valve spring controls the maximum oil pressure to 50 psi and circulation through the oil filter starts at approximately 46 psi if the temperature of the oil is above 135 degrees F. The design of the oil relief valve shuts off circulation to the oil filter at low pressure and permits circulation through the filter slightly before the valve discharge port is uncovered."

[motto]

[quote="
"Engine oil pressure is controlled by a relief valve mounted on the left side of the engine below the starter and consists of a plunger type valve, spring, gasket and plug. The relief valve spring controls the maximum oil pressure to 50 psi and circulation through the oil filter starts at approximately 46 psi if the temperature of the oil is above 135 degrees F. The design of the oil relief valve shuts off circulation to the oil filter at low pressure and permits circulation through the filter slightly before the valve discharge port is uncovered."[/quote]
Looking at the T245 engine I have here it appears to have a similar relief valve configuration to the T214 and T223 engines with no restriction in the return from the filter and no temperature sensing capability. It bears no relation to the system description you quote from the TM.
You have surely encountered a puzzle. I hope we can get to the bottom of it. I have other T245 and T214 engines here so I will see what story they tell.

David

[ng19delta]

There is something that doesn't make sense here. If an original oil filter is bypassed with unrestricted oil lines the oil pressure should dramatically reduce to a very low figure as the restriction is within the filter. By removing the filter from the system with a bypass line the output from the pump should be dumped straight back into the oil pan. From memory it is returned through the same orifice as the pressure relief valve dumps its excess oil. If that orifice is partially blocked it would have the results you describe.
Another possibility is that your indication is faulty.
The TM takes excess oil pressure seriously and calls for immediate investigation as it may indicate a blockage.
The ultimate test is to remove the oil pan and pressurise the system with an external pump and see where it does or doesn't come out.

David

The 230(and all Chrysler in line engines of the day) already bypassed the oil filter, so to speak: It is in parallel with the lubrication passages- oil does not have to pass through it- actually, I think the number is only 10% of the oil passes through the filter at any point... This was before the days of the oil having to pass through the filter... When the engine is running, it comes through the pump, and into the main passage along the side of the block: from there it ports to passages for the bearings, etc, and another hole takes some to the filter. The filter itself does not provide the restriction t o the oil flow, as a blockage in the filter circuit would simply keep oil from entering that part of the system, while still allowing flow through the rest of the system. The bypass is in the same passage- but does not control, nor is controlled by, the oil filter. It simply opens when a blockage causes excessive pressure.

Another reason for high oil pressure is the grade of oil being used, and the temperature. If the oil is too thick, it will have high pressure- but whatever it is cold, as the oil warms, the temp will drop: and a 35lb pressure at warm idle sounds reasonable. Remember- often the gauge indicates twice what actual pressure is, depending on the gauge...

Scott

[ng19delta]

[quote="
"Engine oil pressure is controlled by a relief valve mounted on the left side of the engine below the starter and consists of a plunger type valve, spring, gasket and plug. The relief valve spring controls the maximum oil pressure to 50 psi and circulation through the oil filter starts at approximately 46 psi if the temperature of the oil is above 135 degrees F. The design of the oil relief valve shuts off circulation to the oil filter at low pressure and permits circulation through the filter slightly before the valve discharge port is uncovered."

Looking at the T245 engine I have here it appears to have a similar relief valve configuration to the T214 and T223 engines with no restriction in the return from the filter and no temperature sensing capability. It bears no relation to the system description you quote from the TM.
You have surely encountered a puzzle. I hope we can get to the bottom of it. I have other T245 and T214 engines here so I will see what story they tell.

David[/quote]

I think the manual is referring to the temp of the oil warm, as opposed to cold, and not indicating a temperature sensing device.

Scott