ET: Engine (Twin) Sparkly oil!

[Peter Holmes]

I aways run with a magnetic sump plug, at every oil and filter change I normally see a small amount of very fine grey paste on the magnet, rubbed between forefinger and thumb it is smooth, very fine, grey not shiny and without any hint of sharpness, the last oil change, and now just checking the magnet again after approx 1000 miles there are some larger fragments of metal, shiny silver, that appear to be flattened and not sharp, like they have been though flattening rollers, but they are small, you really need a magnifying glass to get a good look at the flattened shape, is this a classic precursor to big end failure, I am really not in the mood for a complete tear down of the engine right now, I am not looking for anyone to solve my problem with a remote magic wand, but just wondered what anyones thoughts might be.
I guess something very small passing through the timing chest gears might also produce flattened fragments, but I am not running an ATD and I can't think what else it could be. Back in the days of felt oil filters they were always full of sparkly stuff, but I think that was mainly due to the large idler shedding aluminium, but now I run a steel idler gear (don't we all) and the metal collecting on my drain plug is obviously magnetic.

 

[Alyson]

does anything "sound" different ? Chain is not too tight, push rods set right ?

 

[Robert Watson]

Or a bearing doing what is known as "Brinelling" where the hard surface that the balls/rollers rotate on breaks up. Happened to me on the timing side small roller once. The bits look exactly as you describe.

 

[oexing]

The outer small roller bearing ?? That would tell me the trueing of the crank was far from perfect - or the crank twisted in use , no ? In most cases failures of roller barings start with bad unfiltered oil as grit will cause minimal imperfections in the surface, getting worse in time till looks improve to what is seen below with a new Ducati 860 motorbike and its conrod set. Just from a long trip from Munich to New Delhi and back plus IOM and not quite back . . .

Vic

 

[Peter Holmes]

Not quite what I wanted to hear, but not surprised either, come what may the engine needs to come apart, these problems do not improve if left, but I am really not in the mood right now, I very much doubt the crank will be to blame, it was/is a Maughan crank, with I believe an INA big end bearing, with very regular oil and filter changes, but bearings do wear out I suppose. I have not noticed any unusual noises, but that is difficult with a Vincent, you are not exactly starting off with the sound of silence, I guess you just get used to the cacophony of sound, hard to filter out what should, and what should not be there.

 

[timetraveller]

It might give you a clue if you run the engine and use a mechanical stethoscope, or failing that a screw driver. One places one end of the device against the engine and the other in ones ear(s) and then moves the engine end around the engine. The noises are horrific and worrying but if there is one place that is causing trouble there will be a different noise there.

 

[greg brillus]

The Ducati failure shown in Vic's pics above were typical of poor hardening of many parts from Ducati at that time.......with non replaceable liners in the rods, many bikes were parked up for long periods until new parts or a better fix was found. The small bearing that Robert mentioned (ET 94) can be an issue.......I've had engines where you literally had to press the crank out of this bearing. Vic's point about the out of true shafts will load up the bearings and is most certainly the main cause of loose outer races in the cases. The thin outer race of the small ET 94 means that it can easily have too much crush in the bearing housing, thus when the case cools, the inner race is too tight to install. I would say this happens to 50% of the new ones i install........the only real fix is to hone the outer race so the inner fits nicely and rotates without any binding at all.......A big issue with bearings is if they are not the correct C3 clearance.......I have an engine here were the 2 ET 92 main rolllers were not a C3 and the drive side roller was seized solid, the crank shaft had been spinning in the bearing for many years.......it basically destroyed the crankshaft, as the shafts were badly worn and the flanges on each wheel were completely gone......The drive side big end nut had chewed the housing webs very badly........This is probably the worst case of incorrect bearing instalation i have seeen on one of these engines........Within the timing chest, apart from the most common cam/follower failures, the spindles and cam bushes do wear a bit, as does the large idler bush and spindle.......even the breather gear tube part suffers from wear as well, especially the alloy ones.......not to mention the original "Floating type" rocker bearings.......these slowly chewing away at the alloy in each tunnel bore.......I always change these and install the ET 100/1 locking feedbolt set up.......all these changes make for a quiet reliable engine.