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Oil reservoir rupture

Discussion in 'Technical and Troubleshooting Torque' at netrider.net.au started by redralphy, Oct 16, 2015.

  1. hi,
    my fg650gs dakar 2000model started spotting oil after rides, from the oil tank area. tank was diagnosed ruptured and weeping oil.
    replaced with after market tank, with advice from bike shop that repairing tank not good idea.
    almost one year later, (but less than 10th ks) the same spotting begins, worse.
    found the seam weeping.
    bought second hand tank ebay, fitted, on test ride had an oil fountain under LHS fairing.
    got refund to sellers credit.
    then i tried to screw/seal original tank sections together, using the best recommended gasket sealer from local auto spares shop.
    seemed ok when stationary, (warming up to check before the time consuming fairing fitting procedure.) fitted fairings, 2 ks up road, the same oil fountain, and on inspection the tank ruptured at top seam, same as the ebay bought tank. the after market and original were weeping underneath.
    ive ordered the only used part i can find in our galaxy, trying to get back on the road (os orders being exxy and take a while).
    - is there a better/the best sealant/glue to join the sections of tank together?
    - could my bike be twisting/stressing the oil tank?
    -has this happened to anybody else? most topics have forum results when googled, this has nothing, well known bmw spares suppliers say never heard of happening!

    hopefully theres a solution, as im getting frustrated with my bike out of action (an good example of why we all need more than one bike!!)
  2. whats it made out of mate
  3. nfi, but google found some random info.
    quite a few threads about leaking reservoirs replaced, and leaking again in short time.

    "Well, I've cycled through several of these Dakar oil tanks only to find that their failure is apparently a symptom of the root problem, not the problem itself. A BMW service wunderkind I am not, so I'm shamelessly relying the technicians for legitimacy of the following explanation.
    Apparently, there is a "release valve" of sorts on the engine head. It has, for an unknown reason, failed at it's sole mission in life causing pressure in the oil system to build to the point of F650gs-oil-tank-seam failure."

    other points ,reservoir is rubber mounted so twisting shouldn't stress it.

    an oil resistant silicone will survive a bit of vibration.. or you could permanently seal it with a decent epoxy.. or JB weld or similar
    • Informative Informative x 1
  4. i believe aluminium, but not 100%

  5. thanks old corolla,
    i had begun to think along those lines.
    tried an oil resistant gasket sealer, silicon would be worth a try, but im leaning towards the epoxy (and try another second hand tank) in the interim, till i can hopefully ride it to my nearest trusted service mechanic and get that release valve possibility looked at
  6. I think there is something in Oldcorollas thoughts. As a design principle, remote oil tanks shouldn't be pressurised. They are, after all, not built like pressure vessels.

    I had a similar problem, on a different bike once, which turned out to be a blocked pipe. There is a certain amount of "breathing" between the engine case, oil tank and atmosphere which has to happen for the engines lubrication system to return oil to the remote tank and pump it through the engine. If this doesn't work as it should your oil might not be getting where it needs to go. The results can be catastrophic.

    Get it sorted, don't just try to block the leak.

  7. gday jstava,
    after swapping tanks, joining tanks, different sealants etc, i checked the oil vent pipe......it was blocked!! a cap for transit/stop crap getting in got pushed up inside pipe by a gorilla stuffing it on(me) and in. couldnt be seen, but i think it caused all the problems, apart from the initial leak (minor). yep, blocked pipe. your spot on.
    thanks for your input mate
    • Like Like x 1
  8. Fluke really.

    Here is how it unfolded for me - this was following a complete engine rebuild:

    It drove me nuts. first ride, test (probably 8 km) ride upon collecting the bike - I had oil everywhere, though a seam in the remote oil tank. I didn't even go home. Took it right back. They sealed it. Second ride, it blew oil past the seal on the threaded filler cap. I took it straight back, again. They dumped the oil. There was WAY too much oil in it - hiding in the sump. Refilled with the right amount of oil. Rode it home. Confident that the oil level would be right, I didn't check the oil hot (as I usually do). The bike was up for rego so I rode it to the inspection - not far. I checked the oil before I went - It was low. confident it would pump up on the ride, I just rode it (1 km) Checked the oil when I got there anticipating it would be full. - There was NONE in the tank! I put in a small amount and started the bike with the filler cap off. I'm thinking oil pump. The oil pumped up to the right level , plus a little (what I'd put in) I put the cap on and rode home. Checked again, without stopping the engine. It was real low again. I put my thumb over the filler cap and could feel the pressure of the return pump trying to get oil into the tank (generally the return pump pumps more oil than the "feed" pump which delivers the oil to the engine,this keeps the remote tank full with all available spare oil). There was nothing wrong with the oil pump. That leaves one thing. Bingo. As soon as I took the pipe off (to blow through, from the engine side towards the remote tank first, air went in but it went "click" and blocked. I took the other end off and blew out a roller bearing! It could move inside the hose, but at each end, it would hit the bayonet and block it. It was preventing the air in the tank escaping which in turn was preventing the oil from being pumped back into the tank.

    How did this happen?
    The second string (B team) mechanic did the engine removal, the "gun" did the engine strip down, the engineer rebuilt the crank with the new rod and bearings (specialised equipment needed), the "gun reassembled the engine, and the "B team" reinstalled the engine, but forgot about the roller bearing he'd put in the breather tube to prevent wasps building nests in it while the engine was out. (this rebuild took a long time)

    I can only speculate as to how much harm I might have done in the 15km or so I rode home with not a lot of lubrication in that new engine. I was not impressed. The "B team" now works elsewhere, not of course, due to this incident on its own.