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Oil Pressure Relief Valve

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jman15

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Recently, I was couple blocks from home when suddenly the oil pressure went up to around 100 PSI. That is not normal for my car as it should be 60 PSI at speed. I quickly returned home and fixed it by repairing the Oil Pressure Relief Valve's little plunger (thimble shaped item).

I have two questions: 1) if that oil pressure valve is completely blocked will there be no oil being distributed to the engine's rocker/camshaft area or to the mains? and 2) does the oil passing through the oil pressure valve go directly from the oil pump or does the oil first pass through the oil filter?

FYI my car is a 67 BJ8.
 
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If that plunger is somehow jammed closed, oil pressure would go higher, as you saw. It is meant to relieve pressure so it doesn't send higher pressure flow to bearings and filter housing and do damage. Oil is scavenged from sump by the pump, sent through the filter and on to the galley to lube the moving bits. Any oil going by the plunger simply drains back into the sump. Usually the spring fatigues or the seat/plunger wear and result in a drop in pressure.

Check your filter seal(s) area for potential leaking in case the excess pressure deformed the seals.
 
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DrEntropy said:
If that plunger is somehow jammed closed, oil pressure would go higher, as you saw. It is meant to relieve pressure so it doesn't send higher pressure flow to bearings and filter housing and do damage. Oil is scavenged from sump by the pump, sent through the filter and on to the galley to lube the moving bits. Any oil going by the plunger simply drains back into the sump. Usually the spring fatigues or the seat/plunger wear and result in a drop in pressure.

Check your filter seal(s) area for potential leaking in case the excess pressure deformed the seals.
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Thanks for the response. FYI, when I removed the plunger in the oil pressure valve I discovered it had a small scoring or burr on one side. This burr had raised the metal on the side of the skirt and I also noted the plunger showed slight wear on only the opposite side of the skirt. So I concluded the scoring was not a recent occurrence and the burr caused the plunger to be canted and stuck partially opened. Once I removed the burr and reinstalled everything the oil pressure went back to normal. Don't know how the plunger got scored but it had to be something passing through the opening and likely was a small piece of metal or sand. So what ever it was I was wondering if it also passed through the rest of the engine. That answer would depend on whether the filter would catch it before then and presumably it would. So from the sump does the oil go A) from sump to pressure valve, to filter then rest of engine or B) from sump to filter to pressure valve and then rest of engine or C) from sump to rest of engine then filter then pressure valve. I'm guessing its A but just not sure.
 
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The short answer is: B)!!! But the relief valve is just part of the galley, not a "first" device.
 
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