E: Engine disconcerting engine noise...

[CoreyL]

We are working on a C Series Touring Comet and when turning the engine over using the kickstart lever, there is a very disconcerting metal-on-metal noise coming from the engine. See video here:

Does anyone recognize the sound or have any suggestion for what to try?

Thanks in advance!

 

[chankly bore]

A couple of things I've come across: generator mounting stud too long and scraping on flywheel, main bearing outer race scraping. Also clutch roller race wrong length rollers and/ or incorrect assembly here.

 

[passenger0_0]

It sounds to occur at a greater frequency than the crankshaft rotation.
I can't see from the video if you have an Alton alternator fitted as these have strong magnets that can cause cyclic loading the unloading of the drive which causes any gear backlash to rattle.

 

[CoreyL]

It sounds to occur at a greater frequency than the crankshaft rotation.
I can't see from the video if you have an Alton alternator fitted as these have strong magnets that can cause cyclic loading the unloading of the drive which causes any gear backlash to rattle.

Yes, the clicking occurs more than once per crank rotation. We also noticed that when we loosened the plate (E212) that secures all the pinions and gears on the timing side, the clicking/clanging seemed to be most associated with the large wheel (E50) spindle which could be seen to twitch and jump each time we heard the noise. There is an Alton alternator.

 

[passenger0_0]

Steel large idlers do ring when tapped and there may be more backlash anywhere in the system.
So do you have an alternator fitted?
If yes, maybe try removing the small driven gear at the alternator and see if this fixes your problem?

 

[passenger0_0]

Sorry, I didn't read that you have an Alton fitted.
I have seen your exact same problem with an Indian 4 fitted with an Alton. Actually it was an Indian V8 but that's another story.

 

[greg brillus]

Comets with altons........the drive gear starts to move on the shaft because the clamping fit of the securing screw and washer......the plastic gear is the issue, the boss center is barely wide enough.......remove the gear and install a packing hard washer behind the gear, then refit the gear, washer and metric screw with some loctite.......This should work ok........Good luck.

 

[brian gains]

large idler hitting halftime pinion retaining nut.

 

[Cyborg]

The gear on the Alton doesn’t look like the plastic one. It looks like it was replaced with a steel 1/2 time pinion. The combination of rare earth magnets and steel gear…..banging against the large idler……

 

[teunvandriel]

Then surely the solution is simple, take off that sprocket and try without it.