Chips of metal in sump

[Anonymous]

Hi Folks,

I was changing the oil and filter this morning - but the job got bigger pretty quickly. This is the first time I have changed either, I've only topped up before. I've had the bike for about 5,000 kms.

The oil had too much silver dust in it for me to be happy, and when I took off the filter cover I saw that it had been sealed with red jointing paste. I wasn't happy with threads of rubber stuff in there either. So I dropped off the sump plate to check the strainer.

The strainer was clogged with red paste bits and black gunge like silastic rubber that hasn't quite gone off yet. And the sump plate was covered with similar stuff, and a good collection of bits of metal. Something in there has busted and ground itself to bits sometime.

I have a scan of the largest metal bits here.

http://www4.tpgi.com.au/kkmiller/bike/motorchips2.jpg

This is a high resolution scan (and about 75K) so it takes more than a full screen. The ruler is in millimetres.

The metal bits have a flat side which is black and the rest of them is just ground up stuff. The biggest bit is about a quarter inch long, they are all about an eighth inch thick. I can't think of where they might come from.

So I cleaned up the whole thing, refilled with oil, added some stuff for older engines that are starting to blow some smoke to keep it a little cleaner, and started it up.

The bike is running quieter, which I think is because it is getting more oil. The oil pressure light always behaved itself, but the strainer must have been like a flow limiter with all that gunk on it.

I will run it for a few weeks and then change the oil and filter again, but next time put some engine oil flush in there to really clean out any residual stuff.

So everyone (Scotty especially - who I think lives inside his motor) any ideas of where this metal might come from? It is cast alloy, not machined steel, and one side
looks like it has carbon build-up on it. It was lying in the sump so it must have a way to get there. That makes it top end bits coming down an oilway, or perhaps bits of piston skirt. Or perhaps bits of something else.

Thanks

Kim

[Anonymous]

looks like some piston chunks to me, if the motor overheated it could turn the pistons brittle....do a compression test.

[Anonymous]

Definitely look like piston bits to me. Judging by all the other crap in there I'd say your engine holed a piston and someone bodged a fix and left all this junk behind.
You have 2 choices. The first you outlined, and I agree that a compression test would be a good idea to verify the health of the engine. If the engine keeps running then there's no problem, they are tough.
Your second choice would be to fully strip and rebuild the engine, replacing any worn parts. If you do this be sure to check the oil pump thoroughly to avoid any repetition. This option will give you peace of mind but will obviously incur a higher initial cost.
You don't say whether there are any other symptoms such as high oil consumption, unusual noises, low power, hard starting etc. These would all influence your decision.
If not then you may well get away with a good flush out. Good luck.

[Anonymous]

The motor starts easy, it runs OK and pulls well, it is noisy but within my tolerance limits for an old aircooled engine, but it uses oil more than I'm happy with.

I've got a call to make to the guy I bought it from to check what engine work he did, and a call to a bike-riding mechanic friend to do a compression check. After that it's a matter of seeing how close I need to get to taking the head off.

Thanks for your replies
Kim

[saaz]

Possibly piston bits. A clutch basket is another possibility, so perhaps check in there as well.

If they did not clean it out properly, and used heaps of silastic, I would guess that the bores were not honed/bored and new set of pistons used...perhaps only one piston replaced. Who knows if new rings were put in!

[Anonymous]

I finally got through to the guy I bought the bike from. He said that the previous owner to him had blown a piston, that's why he sold the bike. My mate then got it going again. He didn't do the work, but took it to a mechanic to do the top end. The mate never looked in the sump because he thought the mechanic would have cleaned it out.

However, he thought the mechanic didn't do a great job on some other stuff, and he charge too much, and never went back to him.

Now I've only got to find my (very good) mechanic mate at home to give the GS a compression test.

Kim