View Full Version : Rebuilt Yanmar 3GM30

09-23-2008, 12:35 AM
"I recently installed a rebuilt Yanmar 3GM30 from a reputable dealer who also lined it up for me. We went on a 3 week trip and while we were gone the engine ran well but has a few fuel leaks. Two "banjo" fittings leaked quit a bit and I replaced the copper washers on either side of the fitting. They still leak a bit but not nearly as bad as before I replaced them. I'm not sure how much torque is required and I'm nervous about breaking something. My main concern is that where the fuel leaves the injector pump there's three standoff kind of fittings and the fuel is leaking quit bad from the bottom of two of them. I talked to the rebuilder and he tells me that there are "O" rings on the bottoms of these fittings. If I remove the lines to the injectors I should be able to put a "deep" socket on them and tighten them, but I was wondering if I could use a "crow's foot". And by loosening the lines to the injectors try to tighten these units. First question again is what torgue should I use and what size are they? I imagine they are metric and I will have to buy some "crow's feet" to do the job. And one more thing ... should I replace the "O" rings? Sorry about the long winded question but I replaced the old engine because I'm and old submariner and my wife and I both aren't fussy about the smell of diesel and I hope to remove all leaks. Any suggestion to fix this would be of great import to me. Regards and thanks in advance."

09-23-2008, 06:35 PM
"Changing the copper packings is good, and you can remove these packings and anneal them. ie take the copper washers and get them red hot on the galley stove burner and then toss them in cold water. They will puff up and reseal. You can do this once. If you still do not get a seal, you may have to replace the line, as the shoulder the copper washer and banjo bolt may have been over torqued and has caved in the shoulder and therefore will be difficult to make a uniform tight seal. The nuts on the fuel injector pump that hold in the delivery valves should be torqued at 45 foot pounds. I am checking this torque number, so hang tough. No do not loosen or replace the orings, try tightening them first. You can pick up a wrench that has an small opening to get through the fuel line then go over the delivery valve hold down nut, which I believe is 15 MM. If you get leaks then you may have to change the o rings. Best to get your self a Yanmar workshop manual, it has all the values. Regards Ron"

09-23-2008, 08:25 PM
Thanks Ron - I've picked up 8 of the copper rings and will replace them all ... only a few cents each so what the hey ... I do have a manual for the little beasty but can't find the information I'm looking as far as torquing is concerned. 15mm - great! I'm thinking that I should be able to loosen the fuel lines and then use a crows foot to tighten the nuts on the fuel pump - probably the same idea that you are suggesting. Thanks for the reply ...