Yanmar Oil Pressure

[sailorboy1]

I searched for past stuff and found lots about Perkins, but........

Yesterday while motoring in my oil pressure was only reading 3 psi and it normally reads 6-8 psi (Yanmar 4JHE). Shutdown the engine and checked level and it was fine. At low rpm of around 1000 it was barely reading anything. The oil and filter only have 10 hours and the engine has never burned any oil since i've had it.

Looking though the stuff on past oil pressure problems for the Perkins I find common items of the sending units and the pressure relief valve. Any one know of common Yanmar ones?

I've had corrosion issues with the wiring harness lately and recently had to jumper around the low oil pressure switch plug to fix that. Would a corrosion problem in the wiring cause a low oil pressure reading on the meter (ie does it read high if I were to ground it, meaning that high resistance due to a corroded connector would cause it to read low)?

Since I was trained to believe my indications unless it was proved to be wrong; I should have dropped the anchor and called for a tow. But the engine was running and sounded fine (but it would till it died due to low oil pressure) so I ran it an hour with the low reading.

[S/V Illusion]

I doubt your 4JH gauge is reading in psi but regardless, the service manual spec for the 4JH series indicates the oil pressure between 3.5 - 4.5 kg/cm2 is nominal. This would correspond to approx 45-55 psi.

[delmarrey]

Check your connections and sender/gauge. The alarm would go off at very low oil pressure. Check the alarm too!

BTW the fitting for the oil pressure is a BSPT, so you can not screw any standard pipe fitting into it.

http://www.cruisersforum.com/forums/...tml#post436218

[sailorboy1]

Alarm is working. Just recently fixed the wiring problem for it, which is why I know what it normally reads and that it was way low (except I've never looked at the meter close with my glasses on to know what the units are and assmed PSI, not that it matters as all I need to know it the normal reading). Hope it's just a wiring problem as the sender is like $150 and I should don't it to have really been low the other day!

[S/V Illusion]

Originally Posted by Don Lucas

know what it normally reads and that it was way low (except I've never looked at the meter close with my glasses on to know what the units are and assmed PSI, not that it matters...!

If you see 3 -4 on the meter and it is NOT psi, that is normal

[sailorboy1]

doesn't get into the "green" till a little after 4, and normally is around 6

[cantxsailor]

Mine is in PSI because its a real tube type oil gauge I bought at the auto parts place. It has never showed more than 30lbs. I have it from several Yanmar owners/mechanics that anything above 10psi and you're fine..........m

[delmarrey]

Originally Posted by Don Lucas

Alarm is working. Just recently fixed the wiring problem for it, which is why I know what it normally reads and that it was way low (except I've never looked at the meter close with my glasses on to know what the units are and assmed PSI, not that it matters as all I need to know it the normal reading). Hope it's just a wiring problem as the sender is like $150 and I should don't it to have really been low the other day!

I have a sender that I removed from a brand new motor 3JH4E. If you find that yours doesn't work right (8-10 ohms) I could sell you mine at a reduced price, if interested.

Did you use a Yanmar filter or aftermarket?

[FrankZ]

Hey Del!!! My panel doesn't work cause the sender is optional... hint hint.

The water temp gauge needs the sensor as well. hint hint.

[sailorboy1]

Originally Posted by delmarrey

I have a sender that I removed from a brand new motor 3JH4E. If you find that yours doesn't work right (8-10 ohms) I could sell you mine at a reduced price, if interested.

Did you use a Yanmar filter or aftermarket?

Thanks I'll keep it in mind and will check it this coming weekend. Now That I understand how the sender works I feel I'm going to find a wiring problem that is causing a resistance from corrosion.

The filter was a Yanmar.

Good thing I fixed the alarm last month or I would have had to believe the reading!!!

[sailorboy1]

And the answer is.......frayed wire connector at the pressure sender. Turns out it takes more than 2 strands of wire. Of course the wire was too short to just put a new connector on it.

[delmarrey]

Originally Posted by Don Lucas

And the answer is.......frayed wire connector at the pressure sender. Turns out it takes more than 2 strands of wire. Of course the wire was too short to just put a new connector on it.

Yep! Too small of wiring makes it's own resistance. Glad you found it. It eventually would have completely severed!