rodgling
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| posted on 23/6/12 at 10:31 PM |
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particles after big end replacement
How much is normal? I've just done a hundred mile oil change after preventatively changing the big end bearings on the new engine (old bearings
looked worn but no signs that it would have been knocking before I bought it), then pottering about below 3k rpm, and found a quite small amount of
very fine particles in the oil. It looks much like what I found in the old engine after it spun a shell, but much less of it.
Should I be worried by this or is this normal? I'm tempted to give it another hundred miles and then see what the new oil looks like.
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jollygreengiant
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| posted on 24/6/12 at 08:47 AM |
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Not a good sign at all. Sounds like more than shell replacement was needed. Also, did you thouroughly wash out ALL the oilways before replacement and
did you replace or clean the oil pump.
Beware of the Goldfish in the tulip mines. The ONLY defence against them is smoking peanut butter sandwiches.
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rodgling
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| posted on 24/6/12 at 08:55 AM |
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No, but the old engine was sold to me as not knocking, and this is borne out by the condition of the bearings I took out of it, which were fairly well
worn but not spun or damaged. I replaced them mainly as a preventative service. So I had thought that a full flush of the oil ways was not needed,
just a few short interval oil changes.
So this could just be some particles that were still in the engine showing up in the new oil. Or they could be newly created. Not really sure how much
to expect from new bearings, I'd kind of assumed nothing.
[Edited on 24/6/12 by rodgling]
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rodgling
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| posted on 24/6/12 at 09:06 AM |
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Hmm, can moly assembly lube cause the appearance of glitter in oil? I've read elsewhere that it can, and I did use some.
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jacko
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| posted on 24/6/12 at 09:13 AM |
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When i have used Moly it turns the oil a silver/ gray i would run it a little longer and change the oil again
what oil are you using to run it in ?
Jacko
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rodgling
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| posted on 24/6/12 at 09:14 AM |
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Just cheap fully-synth 5w40 (the recommended weight for this engine).
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jacko
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| posted on 24/6/12 at 09:21 AM |
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I was always told fully syn oil was bad to run engines in with i would think someone will be along soon to say one way or the other
Jacko
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perksy
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| posted on 24/6/12 at 01:23 PM |
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Difficult to say without seeing the oil
But If all you've done is change the big end bearings then you won't need to run it in as such
Fully synthetic oil should never be used for running in purposes anyway as it doesn't give the mating parts chance to 'bed' to each
other
What state were the crank journals in before fitting the new bearings ?
Did you check for scoring and mic them up for ovality ?
Were the old bearings the same size ? (sizes/details marked on the back of them)
This might sound daft but i saw an XE crank once that had to big end journals that had been ground a different size to the other two 
I'd be tempted to flush it through with some cheap oil and Then fit a new oil filter and change to some decent oil
and then go from there...
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rodgling
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| posted on 24/6/12 at 02:45 PM |
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I gave it a run today up to 5.5k rpm, nothing blew up or started knocking. A quick sample of the new oil after today's run showed nothing
untoward, and cutting open the filter that I previously used showed only 8 visible aluminium coloured particles over the section I inspected (about
1/4 or so) which I imagine is pretty normal. So I'm not overly worried.
I think I'll carry on with a week or two of building up the rpms with the new oil (I agree it's not necessary to run in the new bearings,
but there is also the aspect that, having swapped the engine, if anything else isn't right, I'd like to find out at the lowest possible
rpm & speed) and then do another (probably final) oil & filter change, and see where that leaves me.
The crank looked fine when I fitted the new bearings, only one tiny score on a main bearing which I'm ignoring. I checked a couple of clearances
(both big end and main) and they were bang in the middle of spec so I very much doubt it's been ground.
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