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Yanmar 3GM oil drain option? Could not locate

4K views 8 replies 5 participants last post by  patricks 
#1 ·
I am preparing my sailboat to be splashed which is a newly acquired Southern Cross 31, and started typical maintenance on the Yanmar 3GM (changing oil, replacing belts, fuel filters, impeller, etc...). The previous owner installed a useless - non-functional - in the way - oversized hot water tank to the left of the engine. This weekend I removed the hot water tank and started removing the water pump, etc.. and notice that there was ample room below and sides of the oil pan and started thinking of a conventional oil change via oil drain plug.... but I looked and looked and could not find the drain plug. I looked in the PDF Yanmar manual and could not find any info or location.

Did they not put one in this engine series?

Patrick
Southern Cross 31
 
#5 ·
My Universal engine on my Catalina 30 had a drain plug that I installed a fitting in so I could easily change the oil. I liked that system. The yanmar on my present boat does not have a drain hose so I have to extract through the oil dip stick. I don't think any Yanmar is set up like that.

Tod
 
#6 ·
I have a 2GM. I did a partial rebuild last year. When I had the oil pan off the block, I noticed there was a flat round area that could probably have a plug if you drill and tap into it. Then just put in a plug with an o-ring gasket to seal it. Might work, but using an extraction pump through the dip stick hole works just fine.
 
#7 ·
patrick-
The bottom line, or persistent urban myth, is that there is a USCG regulation or an ABYC practice, or something along those lines, that prohibits oil drain plugs because anything you can screw in, can unscrew from vibration and then destroy your enine and dump all your oil into the bilge and the surrounding waters. I know, there are cotter pins and gaskets and all kinds of stuff like that, but there it is.
Also, MOST engine installations on boats don't have enough room for a real drain pan under there.

So while there's probably nothing to stop you from jacking up the engine, dropping the pan, and having a proper drain fitted, the usual boat installation requires a suction pump to change the oil. (These are becoming normal on new cars when there's a road pan below the engine as well.)

About $70 for a MityVac or similar. Dip tube goes in the dipstick tube, you pump up a vacuum in the big tube/ball, and the warm oil all comes out, neatly for disposal at the sludge tank. I find that judicous use of plastic bags and paper towels, and not letting that damned suction tube whip around and spray oil, makes it a neat process. Store the whole thing in yet another heavy plastic bad in the original box, to confine the inevitable oil it tries to dribble around.
The motorized versions all seem less effective or more expensive.
 
#8 ·
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