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> Sticky pressure relief valve?, Erratic oil pressure issues with new T4 motor
RoadGlue
post May 27 2019, 07:22 PM
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Hey everyone, hope you're all doing well.

My newly built four banger's oil pressure is all over the board and I'd really appreciate any advice you might have.

When the pressure is behaving normally, I'm seeing a pretty normal fluctuation from 10 PSI at idle to 40-something at cruise. However it seems that depending on direction I'm turning (maybe!?) the pressure can jet up to 65+ PSI which of course is alarming. Worried I'm going to blow out seals.

It doesn't always jump up though. It's rather inconsistent.

At idle I've had it stick at around 60 lbs as well. Giving the throttle a jab seems to free it up and it'll drop back down to where it's supposed to be.

I think it's a stuck pressure relief valve. If it were stuck in a high pressure state, would cornering have some effect on the pressure spikes?

I'm using Penn 20-50 and everything I listed was at normal operating temps (130-180 F).

Thanks!!
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ChrisFoley
post May 28 2019, 06:35 PM
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I say its unlikely because the pressure relief valve doesn't work the way you imagine it does. But it is hard to imagine how going around a corner could affect the relief circuit.

Another point - oil pressure above 65 psi will not blow seals. My modified pressure relief valve raises the max pressure to 75 psi. In fact, the first thing to fail if oil pressure actually gets too high will most likely be a galley plug.

Cold oil pressure can easily exceed relief valve design pressure simply because the return passage is too small to bleed off all the excess oil when it's thick.
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