Replacing an Exhaust Elbow on a Yanmar 2GM20!

[onesea]

If you can take it off you can put a new one on in 15 mins.

+1

As others have said, if you can get it off, it’s a ten minute job to refit.
Unfortunately when I did mine, as part of a major refit on the engine when I purchased the boat, the bolts were rusted and welded in. Use load and loads of freeing fluid such as plus gas over a period of a few days. One of mine sheared off and I had to drill pilot hole in broken off bolt, and use screw extractor to remove it. Engine was out in the cockpit at the time under a temporary covered workshop erected over the cockpit, but it was still a job to get it out.

Hope you have an easier job than me, best of luck?

You lucky sod, I had 3 days of sweats the begining of this year,
one of mine sheared ,
the screw extractor would not shift it .
Ended up drilling out the old bolt ,
when running tap down old thread it snapped,
Hit it with BIG hammer and punch it exploded out
Another tap very very gently cleared thread
30 mins later engine up and runnning singing like a baby

Seriously if I can do this any idiot can I mean fit it there was some serious luck involved in removing the third...

 

[Blueboatman]

Those who have performed this decoking task probably know but...The exhaust hose will pop off without force or damage if you ''carefully'' insert a thin screwdriver down one edge a bit-but not so much as to lever a tear into the rubber but just enough to squirt some of your favourite goop into the gap so that it will work its way round and down...
I use washing up liquid as it is water soluble and washes through ( didnt notice any exhaust bubbles)
Repeat at 180 deg round the pipe if you like and it should then simply twist and wiggle free, a few deg of twist, visible movement is enough.. it will pop off and be reusable ( with a new jubilee clamp).

 

[Caladh]

Thanks Mr Blueboatman. I have had the elbow off several times for checking but next season will replace all of the exhaust pipe so your tip to loosen up at the elbow end will prove very useful.

 

[parbuckle]

Failure of the exhaust elbow seems to have caused the demise of many a good engine,some time ago I bought a scrapped Perkins Perama for parts and the elbow appeared to be good but on closer inspection with a pointy thing it began to crumble like a piece of cake and I know from the previous owner that sea water had somehow got into the cylinders and destroyed the engine. I am not a professional engineer but it would be interesting to know if corrosion could cause this part to exit sea water into the exhaust side of the cylinder or would the power the exhaust not allow any back flow bearing in mind that on stopping the engine a fair amount of pressure in the system could cause the flow of sea water to continue exiting the elbow and maybe back into the engine and the antisyphon valve if anything would cause more water to flow as the head of water falls this can only go out through the elbow.( I think ive got that right ).

 

[pagoda]

If you can take it off you can put a new one on in 15 mins.

+1

Nothing really difficult. (3GM raw water cooled here) Getting the exhaust hose off may take some effort, but no more than some grunt & WD40

I'd take the old one out and inspect carefully before rushing off to buy one.
If not perforated or eroded- clean out and re-fit??

The carbon- ish gunge inside my one was easy to remove with a screwdriver and wire brushes. It cleaned up nicely.
Hope you have no trouble with the bolts....

Graeme

 

[Spirit of Glenans]

When I last checked, they were about £130. I think ASAP do them. Shouldn't be too difficult to change depending on access. The flange bolts could take some shifting if you're unlucky. A boat engine mechanic should do this comfortably in a couple of hours probably charge £120.
I think it's wise to check the condition annually. This also has the advantage that it stops the bolts 'welding up' too much.

+1 on checking annually. My last boat had been re-engined with a Beta 13 the season before I bought it. Sometime in the 7 years that I owned the boat, the flange bolts had begun to loosen, allowing the flange to come slightly adrift. Three of them then 'welded up' , the fourth corroded its threads. The gas leakage was'nt noticed until just before I found a buyer. In the rush to get the problem solved quickly I almost took my eye out with a slipping spanner. A boat engine mechanic would have been cheap at the price. Lesson learned!

 

[Zagato]

Finally got around to locating mine, looks OK from the outside but will take it off and check out the inners once I have a new gasket.

 

[ghostlymoron]

Zagato, the rusty marks may be just external corrosion but could be a pinhole from the inside. Examine carefully.

 

[Dustin Oceanside]

The hardest part will be getting the exhaust hose off. You can use Sikaflex for the gasket.

Any suggestions for getting it off other than cutting it?? I just started on the project and it's immediately obvious it will be difficult.

 

[RichardS]

Any suggestions for getting it off other than cutting it?? I just started on the project and it's immediately obvious it will be difficult.

It's a very old thread so I haven't read it ..... but with my engine the best way is to unbolt the elbow first then heat the hose with a hairdryer or boiling water to soften it then pull the elbow off it's studs so you can then use a twisting to and fro motion with some easing oil to ease out the spigot.

Richard