Yanmar 2GM20F oil pressure problems

[mtoppozini]

Hi folks...hope someone can help me out here... I recently bought a Hunter 29.5 with a 2GM engine. It was checked out by a qualified mechanic who gave it a passing grade. However, if I run the engine for an hour or so at cruising speed, (3000 - 3200 rpm) then throttle back, my oil pressure alarm starts beeping. If I then increase the RPM again, the alarm stops. I put a pressure gage on the engine and I get between 30 and 40 PSI. The oil level is fine and I am using a synthetic Yanmar engine oil specifically made for the engine. The engine runs well and sounds fine but the oil pressure alarm keeps sounding when the engine is warm and I cut the RPM to 8000. Any ideas???

Mike T

 

[n624ma]

Trouble shooting

Mike,
Did you have a chance to look at the oil pressure gauge when the alarm is sounding?

You have several possible causes:
1. Worn bearings (probably the least likely)
2. Oil pressure switch out of tolerance
3. Oil pressure regulator adjusted incorrectly
4. Worn oil pump (not very likely)
5. Engine running hot enough to thin the oil (probably also least likely)
6. Restriction in the oil filter (probably also least likely)
7. Leakage at the rocker arm supports.

According to the Yanmar manual you should have about 42-57 psi at 3600 rpm and the switch should turn the alarm on at 1.4 to 4.3 psi.

Your gauge reading sounds like it's in the ballpark, not knowing at what rpm it was taken.

The regulator is not adjustable, my advice would be to check the gauge with the alarm sounding to see if it's the switch.

 

[kloudie1]

Mike, if the oil pressure is not going below 30 psi at 800 rpm, you are in great shape. The oil pressure sender part number is 124060-39542 and it is around $10. I don’t know the point where the sender is supposed to click “on”, but I think it is around 10 psi.. If your gauge is good and pressure is around the numbers you’re quoting, you probably have a bad switch. Ohhhh, that pressure should be measured where the switch is ..