Exhaust elbow

ParaHandy

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On my 3GM I cleaned this out 3 years ago. There wasn't a lot of muck even although it hadn't been done, AFAIK, since fitting the engine in 96. At the time, I wondered if the scratches left on the surface prising the muck off might form a key which would promote future growth of carbon. Well, I took it off last week and it was virtually blocked solid. So much so that it had to be chucked ..

Anybody else seen that happen .. ?

the engine wasn't particularly smokey beforehand although the reason for doing the elbow was that it started to belch blue smoke & unburnt oil at high revs.

Marine Power at Bursledon offer a much cheaper alternative elbow to the Yanmar part. A few years ago, I used to get all the routine stuff, filters etc, from a USA cpy which also ran the yanmar help website and you paid in $ what would cost same number of £ but then Yanmar restricted their sales territory and the US cpy couldn't supply to anyone not in USA. This peeved me but I see that Marine Power now host the website and it has grown into a very useful site
 

boatmike

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One reason for this Para can be running the engine at light loads for short periods, typical of using the engine for "parking" and short runs at low throttle. A really good blast at full throttle for several hours (like a channel crossing) can often blow the carbon out of the manifold and elsewhere. Not when it's that blocked though!
I doubt if a few scratches makes any difference as some cast elbows are rough as rats inside and don't seem to suffer worse for it.
 

ParaHandy

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could be ... although in the years before and after 2004 (when it was last cleaned), I don't think the way I use the engine has changed .... mostly X-channel
 

toad

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Cleaned my 3gm exhaust this winter, it was down to about 3/8 which was probably why it had started to smoke and get hard to start . the the book of lies that came with the engine it says decoke exhaust at 300 hours or something like that.
 
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