The BSA A7-A10 Forum

Technical => A7 & A10 Engine => Topic started by: t20racerman on 08.07. 2011 14:24

Title: Sludge everywhere despite using detergent multigrade and filter.....
Post by: t20racerman on 08.07. 2011 14:24
Hi all

I've been rebuilding my poor neglected A10 for a while now and although I must admit to giving it a fair bit of abuse in the past (see this thread
http://www.a7a10.net/forum/index.php/topic,3769.0.html  (http://www.a7a10.net/forum/index.php/topic,3769.0.html) I was surpried by the amount of sludge I found. I only ever used 20/50 with detergents, and had a filter too. This bike was my main transport for years and as such it got heavy use with little maintnance. It burned oil badly through worn bores and guides and I was chucking in a lot of new oil regularly towards the end. I never actually changed it very often though....

Anyway, to my surprise now I'm restoring it, the sludge trap was over half full, and there was heck of a residue at the bottom of my oiltank. This was a very fine but thick gunge. It made me wonder about the benefits of having a filter although the big end shells were perfect after about 25000 miles.
So, did my filter do the job it should have, leaving only a very fine paste like sludge, or was it a waste of time having it?


PS - This is NOT another oil thread, I just wondered how effective my filter had been, and was it worth keeping it now the engine is totally rebuilt and cleaned out.
Title: Re: Sludge everywhere despite using detergent multigrade and filter.....
Post by: MG on 08.07. 2011 14:44
IMHO a filter is definitely worth having, especially with modern oil and its detergents.
I'd say whatever passes through the filter is so small it won't do any harm in the engine. Big end shells in excellent nick after 25000 miles are the best evidence.

Just a thought, but since you mentioned you had neglected the bike a bit, did you ever change the filter? The spin-on cartridges (and the new version of the MAP kits) got a bypass valve that will let the oil pass unfiltered once the filtering element is clogged.
Title: Re: Sludge everywhere despite using detergent multigrade and filter.....
Post by: t20racerman on 08.07. 2011 15:21
Just a thought, but since you mentioned you had neglected the bike a bit, did you ever change the filter? The spin-on cartridges (and the new version of the MAP kits) got a bypass valve that will let the oil pass unfiltered once the filtering element is clogged.

I did change the filter now and again yes.

The big ends being so good does seem to suggest nothing sharp, big or damaging was getting through doesn't it? Think I will keep it as it was with filter and multigrade, but I was still surprised at how full the sludge trap was. It was like thick black rubber soot!
Title: Re: Sludge everywhere despite using detergent multigrade and filter.....
Post by: fido on 08.07. 2011 16:06
Hi Ade, I think the wear on the bores is often more down to the lack of an air filter rather than poor lubrication or contaminated oil. Even since the '80s oil has probably improved so you will hopefully get less sludge formation in future. You probably remember my old blue Mk1 Escort I had for a while at college? When I took the rocker cover off that to do the valve clearances you could hardly see the rockers for sludge!  *lol*