Low Oil Pressure Questions


Old 06-14-02, 05:19 AM
Mr. Kiss
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Unhappy Yanmar 4JH2-HTE Low Oil Pressure Questions

Have a problem with low oil pressure on this turbo Yanmar and wondering if anyone has seen similar readings.
I've checked the electric guage and changed the sending unit but still reading low so suspect a weak regulator spring in the filter bracket or perhaps the safety valve bypassing in the pump. This engine has been well maintained with frequent oil changes (don't have hr meter reading right now however). I plan to rig a mechanical pressure guage to the sending unit port today to check actual pressure before tearing into the pump.
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Old 06-15-02, 07:42 AM
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Hello: Larry

Low oil pressure can be caused by several possibilities, if in fact there really is a low oil pressure problem. Your onto the correct track by mechanically checking the pressure.

Since you have already replaced the sending unit and checked the guage to no avail, it may be possible there is an electrical resistance problem in that specific circuit.

In order to determine this, use a volt/ohm meter and take some readings at various locations. Also insure that all electrcial connection points, terminals and wiring are free of corrosion etc.

Do not forget to check the ignition switch contact source of power for the gauges, fuse locations and grounding sources. The idea here would be to first eliminate all electrical problem possibilities prior to any mechanical repairs.

If you have not already done so, check all online sources of information provided by the engine manufacturer or owners of the engine brand etc.

Post back any and all final results on this specific problem. The forum topic readers will all learn by doing so and we appreciate it. Use the reply button to post further updates, etc. Thanks.

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Old 06-20-02, 05:19 AM
Mr. Kiss
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Hi Tom,
Thanks for the reply on this thread.
I was finally ably to get out on the "can" yesterday and do a mechanical oil pressure test.
At idle (about 850 RPM) I was reading around 37 PSI which to me would say that's plenty of pressure. I again did my tried and true circuit testing method of grounding the sending unit lead which should send the guage to its highest deflection and it did. This leads me to believe that perhaps the needle on the guage has somehow moved itself to a lower position so will forever read low.
I'm thinking about replacing the electric guage to see what happens. Besides, I think for we old salts it would be nice to read the pressure in PSI rather than the metric kg.
Any other suggestions?
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