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  1. #1
    Join Date
    Nov 2015
    Location
    Cape Cod
    Posts
    3

    Default 1 GM oil line leak

    Greetings:
    I have an old (1979 or '80) 1-GM in my catboat, which has slightly over 500 hours on it. It's been absolutely trouble-free for the 11 years I've owned it, until July, when one of the two oil lines which runs across the front of the engine corroded through and began leaking. I replaced both lines. The one which leaked before, the longer of the two (which runs from next to the oil filter to a point on the port side of the block) sprang a leak just the other day. I have a replacement; however, I'm wondering if this has been an issue in the past? A bit surprising that the original line lasted 35 years, and the new one 3 months. Anyone out there have any experience with this sort of thing?

  2. #2
    Join Date
    Feb 2014
    Location
    Kitchener Ontario
    Posts
    19

    Default Re: 1 GM oil line leak

    Check you engine alignment and replace your motor mounts ...if need be. Vibration will kill these lines.
    If you still have problems take the lines to a good hydraulic hose shop and get them copied using hi0-press hose

  3. #3
    Join Date
    Nov 2015
    Location
    Cape Cod
    Posts
    3

    Default Re: 1 GM oil line leak

    Thank you for your feedback, Capt'n Squid. The mounts seem to be in good shape (don't know how old they are, but they're intact and don't seem to have hardened or anything like that). Being a one-lunger, it does bounce on its mounts a bit when idling, but settles right down above idle speed. I examined the new pipe which failed; it appeared to have a rough surface (appeared almost as if it had been repaired) and had a small split about 3/8" lengthwise). The dealer replaced the pipe under warranty. That didn't end the story; the day I went to haul the boat for the winter, I discovered another leak, which got worse as I watched it, at one of the banjo bolts. When I went to tighten it, the bolt came off in my hand-it had broken. At that point, I replaced all four bolts (on the two oil lines), together with their copper washers. My feeling is that it is more likely they failed from fatigue (they were original) than from over tightening-but nonetheless I was very careful as to how much torque I used. The manual calls for 18-25 ft/lbs., but there's no room for a torque wrench, so I had to "guesstimate." Hopefully now everything's good, I'll find out for sure in June....

    I like your suggestion regarding high-pressure hose, if it can be made up with the correct size banjo ends. If I continue to have issues of this kind, I'll look into it.

  4. #4
    Join Date
    Feb 2014
    Location
    Kitchener Ontario
    Posts
    19

    Default Re: 1 GM oil line leak

    You have done all. Keep in mind that you have to change the copper washers every time. Overtorque will push the shoulders of the banjo bolt inwards & reduce the face to face contact.
    When I worked for Yanmar I found your scenario happening too often and we changed a few of them. Never during the warranty period. If you grab a 3/8 ratchet and socket at the 90 and wrist twist, that will give you your 18 ft pounds torque. The 1 GM is a good unit and check the out put coupling for dancing as that will indicate alignment is out. should be 4 thou...
    if it continues to be a pain in the ass remove the oil lines and take them to a hose guy.
    A good hose (weatherhead) and Yanmar has p/n for the banjo's only but I can not remember the p/n it has been 11 years since I left..
    keep an eye on them.. happy sailing,

  5. #5
    Join Date
    Nov 2015
    Location
    Cape Cod
    Posts
    3

    Default Re: 1 GM oil line leak

    Thanks again, Capt'n Squid. I'm 99% sure that the alignment is good-I've never moved (or removed) the engine, and had the shaft out once, about 9 years ago to replace the cutless bearing, at which time I checked the alignment when I put it back together. (Given the tough time I had getting the coupling half off of the shaft-took about 5 hours-I liberally coated the shaft, key and bolts with Never-Seez™). It turns very easily, no discernible wear on the transmission tailshaft bearing, etc. I'll be keeping a close eye on it when I re-commission, hopefully this is the end of it.

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