Metal shavings and bits on sump - what to check?

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arbrnrngr

arbrnrngr

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So took head and barrel off son's '74 when, during oil change we found quite a lot of metal chunks (up to 1mm+/-) and shavings drain out. This engine was built by the guys at CB in upstate Vermont and then, according to PO, he put maybe 2,000 miles on it. Bike was immaculate when we bought it. We only put about 400 miles on her, most of it during the 2016 INOA Rally in Asheville.

Finally had time so took the top end off trying to see the source of the metal and can't find anything amiss - cam looks good, crank is clean and turns normal. Tappets and pushrods all perfect. I haven't taken head apart but visually inspects fine.

Is this old metal from the Classic Bike rebuild or what? Where else do I look for the cause of the metal or do I flush it out, put her together and ride? The crank was clearly balanced but of course we don't know when nor if it was taken apart, sludge trap cleaned, etc. but I assume that's standard practice if you're balancing.

I'm leaning towards splitting the bottom end but I also live by "if it aint broke, don't fix it" approach.

Any advice appreciated!
 
Well you gone that far so far but before you do take the oil filter off and cut it open to see whats inside if there is a lot of metal in it then I would take to the bottom end, but if things look good then maybe just put the cylinders and head back on and ride it as 2,500 miles is not much at all.
Not knowing the person who rebuilt the motor is the big factor and for piece of mind going the extra yard with pulling the motor completely apart to be sure in your own mind, but pulling the bottom end apart just for inspection and if things look good a good clean of parts new gasket set and maybe new set of rings and you be sure in your own mind.
As myself I would not have even lifted the head and cylinders, I would have done the oil filter go through the old oil and put new oil in it and ride it for a 100 or so miles then drop the oil again, if there was more metal in it then but it also depends on how much before I would decide to pull it down or not, the oil filter would be the first place to look.

Ashley
 
Solid logic from ashman. Is there any other way of telling where the bits and chips came from by looking at them; check with a magnet and magnifying glass. A general rule of thumb is if you can read the serial number or part number off of the bit in the sump, you have a problem

The two other things to consider are main bearing fragging (you probably would have heard or felt something by now so not likely) and something in the timing chest. You can get swarf and bits of rubber off of the cam chain tension slipper but that is about it. Tear open the oil filter and read the bones, if not much there I would be inclined to button it up, run it and monitor it.

I would also call the rebuilder and tell them what you are seeing; maybe they will give you some insight.
 
You are going to have to call the rebuilder. Be nice and civil yet concerned. You need to inspect the bits for clues. Curved roller bits ? Brass bits ? Steel whatever bits ? Aluminum bits ? Cut open the filter.
 
Are shavings magnetic? If yes look at ferrous components, otherwise cases.

Any non stock holes in the cases? If yes, possibly PO drilled with cases together. Inserting helicoils such as in the inner primary case mounting holes would create aluminum chips that would get into the sump.

I would follow Ashley's advice. Run 100 miles and check again.

Slick
 
There is no reason for such swarf to be present in the engine if it was properly rebuilt. I don't disagree with Ashman, however, I think you did the right thing by opening it up. I also think that the suggestions made earlier about seeing if the particles are ferrous or non-ferrous and doing the forensics on the guts of the oil filter are smart moves.

Do the rods feel uniformly smooth when you rotate the crank through 360 degrees? Obvious excessive crank end play?

If the swarf in the bronze sump filter got to the (external) filter it had to go through the oil pump; you at want to check it, and while you're in the timing chest it's a good opportunity to check the cam timing. I once found 15 pins between the marks on the intermediate gear and the cam sprocket on a customer Norton that came in running, not well; worth a look.
 
Does your drain plug have a magnet on the end of the drain plug, if it does is there metal stuck on it if not then it could be bits of broken thread from the drain plug hole which will be bits of alloy, its easy to damage the thread on the drain hole and the bits drain out when the oil flows out.

Ashley
 
Yes, lots of magnetic/ferrous gunk - that was the whole point so apologies I didn't say this - it miserably failed the magnet test. Not aluminium at all that I see yet a lot of iron on the magnet. Yes, drain plus has the magnet but also drained into the pan and dredged magnet around and picked up lots of metallic bits. No helicoil (lots of experience there in the Army working on engines). Rods feel smooth and rotate fine - I 've taken the pistons out so as to rotate all - and it's in good order from what I can tell. Absolutely no roughness.

Cases were repaired from what I can see and Classic Bike guys mention that this motor (which is Gus I, their original custom) has a hole in teh case they repaired = which I can see inside and all looks fine (plus it's aluminium of course).

So I think I'll make the investment and split the cases, remove crank and basically rebuild. Yes, I respect the opinions of those suggesting to put her back together for 100 miles but at this point I'm in for a penny and in for a pound so worst case is I disassemble, find nothing and put her back together.
 
Gunk to me sounds like swarf which is usual in the oil and magnet on the drain plug. Lots of chips and chunks, is not so good. Sources of metal swarf typically include the the rings bedding in to the cylinders, the cam chain tensioner, if it is metal to metal, and the oil pump ends, especially if they were lapped in upon rebuild. You should also have a close look at the cam as it may be a soft one and is beginning to whittle away. As you split the cases, consider splitting the crank to clean out the trap of any loose stuff. Good luck with it and please share what you find.
 
arbrnrngr said:
So took head and barrel off son's '74 when, during oil change we found quite a lot of metal chunks (up to 1mm+/-) and shavings drain out. This engine was built by the guys at CB in upstate Vermont and then, according to PO, he put maybe 2,000 miles on it. Bike was immaculate when we bought it. We only put about 400 miles on her, most of it during the 2016 INOA Rally in Asheville.

Finally had time so took the top end off trying to see the source of the metal and can't find anything amiss - cam looks good, crank is clean and turns normal. Tappets and pushrods all perfect. I haven't taken head apart but visually inspects fine.

Is this old metal from the Classic Bike rebuild or what? Where else do I look for the cause of the metal or do I flush it out, put her together and ride? The crank was clearly balanced but of course we don't know when nor if it was taken apart, sludge trap cleaned, etc. but I assume that's standard practice if you're balancing.

I'm leaning towards splitting the bottom end but I also live by "if it aint broke, don't fix it" approach.

Any advice appreciated!
Click to expand...

The engine builder being held accountable usually likes to do the exploratory surgery.
Interested in what you find, I've had the same artifacts showing up, and need to find the sourcethis winter.
 
Last edited:
concours said:
The engine builder being held accountable usually likes to do the exploratory surgery.
Click to expand...

The corollary to this is: "If you want it done correctly, do it yourself". Not trying to be contrary here; the engine builder would naturally like first dibs at it, especially under fee. It comes down to a matter of trust where the builder has had their chance to be trusted; perhaps now is the time where the engine builder trusts the owners findings. I have a hunch that
arbrnrngr knows a thing or two about tearing down a Norton twin. The flip side of this is that I would certainly keep the engine builder in the loop on this.

Just another perspective here.
 
few years ago fitted a new sump plug with magnet... to my horror next oil change produced metal mostly trapped on magnet... the whole plug had been chrome plated and this plating had come away when plug inserted...hope its nothing more serious... if the bits are small then i would suspect cam chain tensioner-- the chain just loves to cut groves into the slipper
 
Yes do it yourself but keep the engine builder in the know what you find, if its something major and it was from something he has done wrong, but wheather he will except it is another matter, but by the sounds of it its doesn't look major in what you have been saying so far, most engine builders do a quick job of cleaning parts when pulled down, in a cleaning tank with a stiff brush, myself soak all parts from cases to cranks head and cylinders for days at a time fully submersed in kero then a good scrub down and resubmersed for another day then blowin out with high pressure air, it might be time consuming but is worth it in the long run.
It might have been something he has missed while cleaning, parts that have been machined and a bit of swaf he has missed, but in your own mind it will be better off going the full tear down, good luck with it.

Ashley
 
I'll finish the tear down but so busy at work, it will be the winter project. Dances w/shrapnel, I've checked the cam and see absolutely nothing wrong. That might change once I can see it disassembled but for now, nothing visual. So apart she comes. I'm starting to think somethings amiss on the timing side and am thinking I got there before the real damage happened (again - as I said, this motor blew a hole in the crank case before the guys at CBE fixed it).

At least I now have a winter project to keep me occupied.
Thanks to all the input. I very much appreciate everyone's wisdom and, above all, time.
kevin
 
An interesting question: Are experts that do work on your classic motorcycle or any of its components, for a fee, allowed to make mistakes? When you fix a major issue with a patch rather than a new part or an undamaged part are you doing the customer any favors?
 
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