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Hi, I've got a 1993 L3 which has just developed a very loud engine rattle. I realise that without seeing the bike and hearing it it's pretty much impossible to diagnose and suspect I'm looking at a replacement engine here but I just thought I'd see if anyone had any ideas before I began to source one. There is no history to it, it's not been overrevd or dropped - it just suddenly started for no apparent reason. I've been down to my local bike shop and without stripping it they couldn't say where it was coming from, but agreed it does sound very bad indeed and it isn't the cam chain. It goes up and down with the engine revs and about the only useful diagnotic help I can give is that it still seems to be running on all 4 cylinders and if the engine is under load i.e. under aceleration the rattle seems to go away when it gets to 4000 rpm. Engine oil level looks to be where it should be but it does look white or emulsified in the inspection window. There is no sign of anything coming out of the exhaust and the bike is well looked after and has only done 17,000 miles.

Grateful for any help please?

the insection windows always have a bit of white on them if the bike hasnt been ridden recently, likewise the filler cap can be a bit foamy as well, nothing to worry about.

Clutches rattle a fair bit on these bikes and clear up around the 3k mark.

The hardened faces of the rockers can lose their hard coating and chew themselves in 50-100 miles once its gone, that causes a tap/tink sound from the top end.

If you can get the engine out that would be a bonus, i would check the cam chain tensioner, the tensioner guides, the cam chain, then i would check the valve timing, pull the cams out and check the condition of the cam lobes and the rockers, finally i would pop in new exhaust gaskets, check/replace the clutch, check the condition of the clutch basket for excessive wear and then fire it back up and see how it seems.

as banner says, replace the exhaust gaskets first. I had a very similar problem, which sounded like a serious engine fault. Turned out changing the 4 copper gaskets for £6 sorted the problem completely!

Thank you very much both.

Jamie: I read your earlier post about the exhaust gaskets and was hoping that might be it. But how loud was it? This is very loud. Consensus at the bike shop was it could be rattling a big end out. It really does sound awful.

Banner - thanks for the advice regarding sequence. I don't think it's the clutch rattle I'm familiar with that and the mechanic at the bike shop didn't think it was the cam chain, so it's probably onto the other things you recommend. Is it possible to strip the engine in the frame or does it have to come out altogether. I suspect the answer to that one is going to be "yes" but thought I'd check. The problem is going to be finding somewhere to store the bits in as I strip it.

Thanks again both for coming back to me.

It's possible to strip all the way down to the head gasket with the engine in the frame, but remove the radiator to give you a bit more room to manoeuvre.

If nothing else you will know that the top end is fine.

Many thanks everyone. Think I'll start at the top end and see how it goes.

Sorry for the delay! It was pretty loud, easily could hear whilst riding, and also had a few others saying sounds like the engine's knackered!

JamieNeve wrote:Sorry for the delay! It was pretty loud, easily could hear whilst riding, and also had a few others saying sounds like the engine's knackered!

Many thanks Jamie.

In case it helps anyone, I finally found out what the problem was. The rear cam chain tensioner blade had snapped. It wasn't apparent until I removed the cam chain - it looked fine till then - It was still in place and where it should be, but when I took the cam chain off 3/4 of it fell out (the top part is held in by a screw) and so it wouldn't have been doing very much.

I replaced the cam chain and the tensioner blade and she's running as sweet as a nut again.

Thanks to all that helped and especially Banner.