Oil pipe / crankcase union

[BobbyG]

Hi All. I'm having difficulty getting an oil-tight seal where the upper oil pipe screws in to the crankcase of my 1955 16MS. The crankcase 'socket' has been bodged at some time in the past with Lumiweld or just poor aluminium welding, and may have cracked again (can't actually see where the oil is coming from) and I can feel that the threads are about to strip completely if I tighten any more. The best solution would probably be for the whole 'socket' area to be built-up again with aluminium weld, then drilled and tapped but this would necessitate a full engine strip-down and even then, would it be viable? Is there anyone out there who does this kind of work? Would it be better to find a replacement crankcase/side? What about aluminium epoxy paste as a bodge on bodge? ...or should I just try and live with the oil leak? Your thoughts would be much appreciated.

[Mick D]

Hi

I'd live with it whilst I found a replacement or saved up the cash for a professional weld repair. Another repair option is to machine away the damaged thread and fit a threaded sleeve - similar process to a helicoil but will be more leak tight and structurally sound if the case is cracked.

Regards Mick

[Rob Harknett]

It is over tightening that cracks the crank cases. You need good clean ball & socket joint faces to prevent oil leaks here. If you do the union up tight it will surely crack. If you can see a crack. Give the area a good clean, screw in the union until you see the crack again, run in some araldite. Remove the union so the crack closes, leave a day or two. Check the pipe union is clean and scratch free. Find some to fit in the pipe and protrude out a bit, apply a little grinding paste on the union. Grind in the seat with the union. Clean out. Then replace taking great care NOT to over tighten. You may still get a little oil seep out. ignore it. It is a bodge, but one that worked for me and still Ok after over 20 years, on one of my bikes found to have the common crack. All of which have been caused by previous owners not following the do not over tighten warning.

[Andy51]

My '54 18S engine was rebuilt by the late Malcolm Saggers, and engineers don't come any better than him. He solved this problem on my bike by boring out and tapping the crankcase, making a screwed adapter, and connecting up the oil pipe with a short length of rubber piping and 2 jubilee clips. It sounds a bit of a bodge, but it doesn't show and has been totally reliable for over 10 years and, as I said, Malcolm was brilliant at engineering solutions and never bodged anything - an engineer's engineer! It does mean a complete strip down but any good engineering shop should be able to do the job. If you want photo's, etc, send me a PM. Andy