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nknowland · 08-03-2016, 11:27

Westerbeke 52 oil gauge ran high (85-90psi) on a recent offshore cruise. Never had this issue before and most posts here suggest the oil sender, but that was replaced less than a year ago, along with oil gauge.

A neighbor on the dock loaned me an oil pressure test kit. Can I get an accurate test by running the engine at idle and then revving to 2000 rpms at the dock?

Lepke · 08-03-2016, 14:32

In gear you should get the same pressure. Out of gear at high rpm there isn't crank resistance to turning so it's easier for the oil to move thru the bearings and possibly less pressure. But the test should be good enough whatever you do.

DougR · 08-03-2016, 15:40

W 52 manual states the operating oil pressure should be 50-65 psi. When warmed up it should be at least 54psi at 3600 rpm.

Suggested procedure is to warm the engine and then take psi readings with the electrical gauge at rpm intervals of perhaps 500 rpm up to 3500 rpm. Then remove the electrical pressure sender and install the mechanical gauge into the same port that the electrical sender came out of. Repeat the test and compare the readings. This should tell you what you need to know.

The oil pump is equipped with a pressure relief valve which should open and release excess pressure back into the crankcase. This normally occurs when the oil is cold, and helps protect the oil pump from damage, but it's possible that the spring/ plunger in the valve are stuck and not dumping excess pressure. Your mechanical gauge test should point you in the right direction.

DougR

nknowland · 08-03-2016, 17:16

Thanks Doug. Took measurements today with electrical gauge....steady 75psi. I'm thinking it's the sender. (Hoping it's the sender one-year of oil pump!). I'll do mechanical test tomorrow.

guyfromiowa · 08-03-2016, 18:23

I use a test kit like this one

Amazon.com: GearWrench 3289 Oil Pressure Tester Kit: Home Improvement

Unscrew the filter, install the adaptor, start the engine. Faster than taking out the sending unit and you can compare mechanical reading with instrument reading with the engine running.

deblen · 09-03-2016, 14:15

Oil filters can fail internally & restrict the flow of oil causing high pressure. There is usually a bypass valve that opens if this happens. I think this is the valve that Doug speaks of.

Cheers/ Len

seabreez · 09-03-2016, 16:21

Westerbeke 52 oil gauge ran high (85-90psi) on a recent offshore cruise. Never had this issue before and most posts here suggest the oil sender, but that was replaced less than a year ago, along with oil gauge.

A neighbor on the dock loaned me an oil pressure test kit. Can I get an accurate test by running the engine at idle and then revving to 2000 rpms at the dock?[/QUOTE]

Before doing a pressure test, I would do an oil and filter change with proper oil for that engine. Just in case the oil is contaminated and giving you a false reading when comparing to manufacturer specs. I would do a before and after... test

**a64pilot** · 09-03-2016, 17:41

Quote:

Originally Posted by deblen

Oil filters can fail internally & restrict the flow of oil causing high pressure. There is usually a bypass valve that opens if this happens. I think this is the valve that Doug speaks of.

Cheers/ Len

Yes they can fail, but it's extremely uncommon, I've never seen it myself.
In the event of failure, there is often a bypass valve, really there in case the filter clogs and or a cold oil bypass valve, but it won't raise pressure, it will lower it as there is a restriction up stream of the filter, and down stream is where pressure is measured. This valve is often in the oil filter adapter.
However there is an oil pressure relief valve, it's job is to keep pressure from going too high on a cold engine during warm up, all I have seen are a ball that sits on a hole, with a spring that holds it closed. Very often this valve is in the oil pump.

I have never seen an engine that had the proper grade of oil have excessively high pressure once fully warmed, but I have seen more bad gauges that I can remember.

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**a64pilot** · 09-03-2016, 17:44

Oh, pressure will read high of course until engine is fully warmed up, and engine oil, not coolant of course. So if possible make sure it's fully warmed by using an IR temp gun on the oil filter itself. I'd consider a temp above 150 F to be warmed up enough so oil pressure ought to be normal.

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nknowland · 10-03-2016, 15:07

Thanks for all the useful ideas.

The pressure test showed 60psi at all rpms. Oil and filter were changed a month ago but I put on a new filter anyway. Installed a new sender today and gauge is still reading 75psi at all rpms. And it's a steady 75psi from initial start to complete warm up (not seeing any drop as engine warms). Is that a problem? I am in South Florida so no cold weather to speak of.

The oil relief valve is inside the oil pump on a W52 so not something I can access.

Next up, should I replace the oil gauge or just go on the reading from the mechanics gauge test?????

**a64pilot** · 10-03-2016, 17:09

60 PSI at all RPM points to a really strong as in very little wear engine, when they get tired you'll see 15 PSI or so at low RPM and only good pressure at high RPM when warm, cold will show higher pressure of course as cold oil is thick oil.
Myself I would change the gauge to one that works, all you know now is its broken, but having said that all I have is a buzzer that goes off at some unknown to me low pressure. Ideal I believe is both.

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