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Suspected problem with cranshaft?

PostPosted: Sat Oct 12, 2019 2:45 pm
by Herbert
Seeking your thoughts please:

Before I start stripping the engine down, I think there is an issue with the crank.

When reducing the revs of the engine to near tick over, a fairly high pitched, rattling noise is coming from the top end area. The rattling noise then disappears as the revs are increased. Could the crank and/or con rod be distorted or is it a disintegrating big end bearing?

I will work on the engine soon and to see what is going on, but as anyone experienced such a rattling noise to discover that the crank was at fault? I would also be interested to know what happens when the crank does give up especially when the engine is turning. Does this result in a seizure within the barrel?

Thanks for reading. H.

Re: Suspected problem with cranshaft?

PostPosted: Sat Oct 12, 2019 3:24 pm
by MickYork
I had similar with a little end bearing. When stripped the conrod eye was slightly oval.

Re: Suspected problem with cranshaft?

PostPosted: Sat Oct 12, 2019 4:55 pm
by Herbert
Thanks Mick.

Re: Suspected problem with cranshaft?

PostPosted: Mon Oct 14, 2019 6:11 am
by Toddy
H , Strip and inverstigate try and find the problem if it is the Small or Big end bearing and it does let go it can cause serious damage to the top end and casing

Re: Suspected problem with cranshaft?

PostPosted: Mon Oct 14, 2019 10:55 am
by Rich Oswald
Toddy wrote:H , Strip and inverstigate try and find the problem if it is the Small or Big end bearing and it does let go it can cause serious damage to the top end and casing


Don't I know it!