Brad The Bike Boy: Odd alternator cover leaks

Saturday, July 30, 2016

Odd alternator cover leaks

I'm on a roll now, so possibly the second in a three part 748 tale of woe.

I had another 748 in recently, just purchased sight unseen from interstate from a shop I believe. Allegedly a low km (3,500 miles) import, clearly bought from a bloke with a very long nose and charred pants. It's really sad to see people get ripped off like this.

Apart from a couple of basic and unmissable compliance issues - LH drive headlight and non approved braided brake hoses - it had undersize front brake discs, front brake and neutral lights not working, steering stop broken off the frame, rusty steering head bearings and more. Minor detail stuff too, like normal screws holding the mirrors on instead of the brass, breakaway head screws, screws holding the seat on instead of the plastic pins and rubber keeper and no tank pin grommet in the front of the airbox, which was contributing to the steering damper taking the paint of the front of the tank on the RH side. Again (self righteous wanker statement time) just work done by someone who doesn't know the bikes or what causes issues. Some of it well intentioned, some just sloppy.

I worked out the neutral light issue was that the dash / front section of wiring loom was for a late style single wire neutral switch, where the switch completes an earth circuit through the engine, while the neutral switch and rear section of loom was the older two wire 12V continuity switch style. To make the light work I left the switch wire from the dash globe connected, and made a little wire to go from battery negative to the other (originally 12V power) switch wire to earth out the circuit and bring the light on. Simple, but never going to work as was.

Another was oil leaks from the alternator cover. Usually they leak from the clutch pushrod hole, caused by the clutch slave (which is bolted to the cover) trying to pull the cover off the crankcases every time you pull the clutch lever and stressing the goop over time until it no longer seals. Often the cover screw behind the slave is loose too, in this case it might have been too long and not bottomed. Anyway, I pulled the cover, looked for other obvious issues, cleaned, gooped and refitted. I also replaced the rotation sensor o-ring (old two screw pickup, original o-ring now NLA) and applied some more goop, which I really don't like doing when o-rings are involved unless I really have to.

Then I went for a ride and parked it to see what it dropped and to my profound dismay it started immediately. At which point the source of the leaks became a little more apparent. Certainly nothing I've ever seen before either. The video shows oil bubbling out from under some corroded paint near the top of the cover, around the unused boss originally for the crank sensor on P8 ecu models.

It had more leaks, under the DUCATI logo at the bottom of the cover and a couple up at the front of the water pump below the rotation sensor. Again, just oil coming through. I don't know if it's just porous or if it is residual crash damage. While trying to find a replacement cover I spoke to Shaun at D Moto and he said in his DDT days that they used to see the race bike covers do similar things after crashes. No obvious marks or damage on the outside or inside, just leaking.

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