Bronze Glitter in Engine Oil

gearguy2012

gearguy2012

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Nov 8, 2015
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I had a not so pleasant surprise last weekend. It had been about three weeks since I last rode my Commando. If I go more than two weeks I drain the oil from the sump before starting. This time I was not happy to see oil that was full of bronze color glitter. The glitter is very fine and not magnetic. The magnet on the drain plug was clean and so was the large sump plug. I have experience with transmissions and this looks like a bushing issue. I am looking for advice on likely areas I should be looking carefully at. I only have been out for a couple short rides this spring and had not noticed any performance or noise issues.
 
Camshaft bushes, timing idler gear bush, valve guides if bronze and the top plate of the oil pump are all the yellow metal I can think of in the engine oil areas. Start the engine and check inside the oil tank to see that oil is returning. If not stop and strip the engine :(
 
What year is your bike. 72's are notorious for having the tab break off the bronze cam thrust washer.
 
Could be an issue. Could be ok.

I‘m not being flippant, just trying to be balanced. These old engines aren’t the same as new ones!

Unless you’re a racer, or planning a super long trip, or enjoy stripping engines for fun, first thing I’d do is fit a filter (if it hasn’t already got one), and ride it and keep an eye / ear on things.
 
If it was the gearbox, I'd not be surprised, just change the oil. But the engine, esp one that is independent of the rest of the bits, I'd want to be a lot more careful. The test is the way to go. Test cost is nothing compared to possible engine damage costs.
 
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Genuine question: what is the test going to show that is not already known?

As posted above, there’s only a few sources of yellow metal in a Norton engine. Is the test going to be able to tell if it’s a cam bush or oil pump plate ?
 
Fast Eddie said:
Genuine question: what is the test going to show that is not already known?

As posted above, there’s only a few sources of yellow metal in a Norton engine. Is the test going to be able to tell if it’s a cam bush or oil pump plate ?
Click to expand...
Genuine answer, not all that glitters is gold.😎

Rod bearings, will leave a signature in the oil sampling (tin) and as such, should be taken out of service NOW, versus waiting until the broken rod buzz saws the cases in half like has happened to a few here.

JMWO


www.accessnorton.com

Why we call it "inspection"...(2018)

'74 Roadster, 43,000 miles (of which, the last 31,000 were well cared, not abused, and there is no reason to think the first 12,000 were different). No unusual noise whatsoever, and I listened. Timing side main has failed.
www.accessnorton.com www.accessnorton.com
 
Fast Eddie said:
Is the test going to be able to tell if it’s a cam bush or oil pump plate ?
Click to expand...
And if it does show which metal which is which. There is one other possible source which is if the shell bearings are trimetallic but this would require all the protective plating to have gone and the big ends to start grinding away at the revealed lead bronze layer.
 
Fast Eddie said:
Genuine question: what is the test going to show that is not already known?

As posted above, there’s only a few sources of yellow metal in a Norton engine. Is the test going to be able to tell if it’s a cam bush or oil pump plate ?
Click to expand...
Save the $28, it will buy you maybe a gasket at rebuild time. 🍻

Oil sampling is merely a tool, that can be used to rule out, confirm, give a clue, etc.

NOT the end-all-be-all, but in the hands of a talented mechanic, very useful.


JMWO
 
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Fast Eddie said:
Unless you’re a racer, or planning a super long trip, or enjoy stripping engines for fun, first thing I’d do is fit a filter (if it hasn’t already got one), and ride it and keep an eye / ear on things.
Click to expand...
An external oil filter is seconded, but I would certainly not keep on riding unless the cause for your observation is found!

RCFA (root cause and failure analysis) suggest either grinding of a hard particle against a plain bearing, or oil starvation, depriving the bearings of oil.

1) Grinding at adjacent surfaces - the likely culprit is the oil pump having sucked in a piece of carbon steel (e.g., a chip of a piston ring, or a broken gear tooth).
2) Oil starvation may have happened if you were running your bike without an external oil filter. The suction filter fitted in the oil tank may have clogged up if not cleaned for decades.
Another possibility is a failing oil pump due to gasket failure, a failed oil pump seal, or internal gears having failed, thus not producing pressure and a sufficient volume flow anymore.

There may be consequential failures of cause (such as rod bearings), but at the outset I suggest you inspect oil tank, oil lines, and the oil pump.

- Knut
 
Get a crankcase breather so you don't have to drain the oil every 2 weeks. You'll save the case threads for the drain plug at least. If you are then pouring the drained oil back in then hopefully you are filtering out the road grit that falls into the pan each time.
 
mdt-son said:
An external oil filter is seconded, but I would certainly not keep on riding unless the cause for your observation is found!

RCFA (root cause and failure analysis) suggest either grinding of a hard particle against a plain bearing, or oil starvation, depriving the bearings of oil.

1) Grinding at adjacent surfaces - the likely culprit is the oil pump having sucked in a piece of carbon steel (e.g., a chip of a piston ring, or a broken gear tooth).
2) Oil starvation may have happened if you were running your bike without an external oil filter. The suction filter fitted in the oil tank may have clogged up if not cleaned for decades.
Another possibility is a failing oil pump due to gasket failure, a failed oil pump seal, or internal gears having failed, thus not producing pressure and a sufficient volume flow anymore.

There may be consequential failures of cause (such as rod bearings), but at the outset I suggest you inspect oil tank, oil lines, and the oil pump.

- Knut
Click to expand...
I would suggest that oil starvation would show up more particles, not just yellow metal / none ferrous.

Of course, a full strip and replacement of everything that is not as new would be the best course of action… but it’s just possible that the OP doesn’t need that…
 
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If it was me I think I'd try to get my finger in through the hole and wipe it around the bottom of the sump and see what it looks like. Or get a boroscope and take a look.
 
Fast Eddie said:
I would suggest that oil starvation would show up more particles, not just yellow metal / none ferrous.

Of course, a full strip and replacement of everything that is not as new would be the best course of action… but it’s just possible that the OP doesn’t need that…
Click to expand...
Tell us more...
 
concours said:
Runnin it as is....

I enjoy takin'a risk as well
Click to expand...

Easy in my opinion.

One oil change with a bit of colour in it certainly wouldn’t be enough to persuade me to strip it.

I’d flush it, change the oil, fit a filter, and monitor the situation.

As said already, if it were a race bike, or a Comnoz cross country bike, I might think again. But if it’s a sunny Sunday and club run classic, I’d be tempted to hold my fire at the moment.

Our OP wouldn’t be the first to be tricked by bubbles in the oil either.

Only MHO.
 
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