Oil underneath Yanmar 2GM20

[zachduckworth]

I was replacing my fuel filters recently and noticed some oil drops on the absorbent pad below my engine. There was also some oil, not much, on the bottom of the engine towards the transmission. No oil towards the front of the engine. What would be the most likely source of the oil? Thanks!

[Cheechako]

Wipe it clean and observe it for wetness or drips for a week or two. Find the drip with toilet paper dabbing lightly underneath the oil pan, but then look for the highest wet location, nut the lowest! That may tell you something.
A small amount of oil can look worse than it is though.
It sounds though like you may have a rear main seal dripping from your stated location. It's not transmission oil? Hard to say on the Yanmar I guess as the tranny used engine oil doesn't it?

[lockie]

Originally Posted by Cheechako

Hard to say on the Yanmar I guess as the tranny used engine oil doesn't it?

I agree with all you said except that part: the engine oil will be black while the transmission oil will look like new.


Cheers, Graeme

[zachduckworth]

The transmission uses its own oil. The leaking oil is definitely engine oil, very black. I’m going to do as advised, clean it up, also change the oil and then see where it’s leaking from.

[skipperpete]

First check the dipstick, maybe the front and rear crank shaft seals too but the sneakiest oil leak of all on yanmar 2 and 3GM’s is the oil feed pipe that runs from the front left side of the engine near the oil filter , along to ..and under ….the starter motor then up to the cylinder head to lubricate the rocker gear. The 3GM pipe continues to the RH side front of the engine and has 2 more connections. On your engine the most likely place for that fragile unpainted thin wall tube to fail is behind the starter motor and it usually begins as a tiny weep…. of dark engine oil , and progresses to a jet of engine oil a few weeks later in the worst case scenario. First check the banjo bolt connections.

[Wotname]

Originally Posted by zachduckworth

The transmission uses its own oil. The leaking oil is definitely engine oil, very black. I’m going to do as advised, clean it up, also change the oil and then see where it’s leaking from.

I'd be inclined to leave the oil change until you have located the leak. The darker the oil, the easier it is to find and you may have to drain the oil to repair the leak. No point is draining near new oil.

Skipperpete is on the money about the external oil feed pipe. It is a common problem and almost impossible to see unless you know it is there.

[NorthCoastJoe]

Clean the engine with Simple Green. Then run for awhile and look for the leak.