Author Topic: M32 Oil Pump Drive Dog  (Read 142 times)

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Offline Hamwic

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M32 Oil Pump Drive Dog
« on: 09 Nov 2021 at 11:52 »
Hi all, another M32 tale, and a question if I may?

After replacing the oil spray bar on the M32, we set off down the road again, and apparently all was well. Well, for at least the first 5 miles, but then a gradual tightening of the engine became apparent. The oil regulator was well open, and all the oil was being delivered, but it felt like either piston(s) or big end(s) were going to pick up. A roadside pause to consider my options. The bike restarted but soon warned me that all was not well, with a pronounced clattering, so a push home was called for. By the time I was home, the engine was cool, and turned freely again, but the clattering was audible valve gear perhaps?

A look inside revealed that the timing gear support plate was loose, allowing the valve clearances to vary from negative to positive hence the apparent clatter. There being plenty of oil where required within the cases, this plate was re-secured and a couple of clamping problems addressed. With the clearances reset and the cover put back on, the engine span freely and fired up readily. Off we went again. Within a few hundred yards the tightening again made itself felt, so we crept home again.

With the engine out and the front cylinder off, it was apparent that all was not well with the front big end, it feeling a bit stiff to turn, and the rear likewise. However, when taking off the timing chest cover, the rods dropped down freely. No signs of seizure in the bores.

It transpires that the oil pump driving dog locking screw had gently unwound itself, and was pushing the timing gear plate about. The driving dog had also unwound itself, and was bearing heavily on the pump drive gear worm in the timing cover. This had squeezed the flimsy crank endwise such that it had nipped the big ends between the crank webs. Once the dog was put back from whence it came, and the screw re-tightened, normal clearances are restored.

Perhaps a left-hand thread would have been a better idea for the drive dog, rather than the hard-to-reach and apparently ineffective locking screw?

Im not overly confident that the drive dog will properly stay put, although the thread engagement is very stiff, and the screw has gone further home this time. Is Loctite required perhaps, and if so, which grade? Any other suggestions as to how to secure this dog?

Cheers for now
Doug

 

motorcycle