Yanmar 3YM20: cleaning exhaust elbow

charles_reed

charles_reed

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Has anyone any experience of doing this 1000hr maintenance task?

Detailed instructions on all other maintenance requirements but not a word on this.

Do you unbolt it from the head, or can it be cleaned by removing the muffler hose?

Any other tips welcomed.
 
Just cleaned the one on my 2GM20F. I was replacing it anyway and so removed it completely. The problem was not removing it from the engine but the exhaust hose was completely heat hardened onto the old elbow and I had to cut the hose in two to get it off and then replace the hose. Fortunately it was only a short section that connected the elbow to the water lock.

After fitting the new elbow, out of interest, I then cleaned out the old one to see what it was like. It took some pretty serious chipping with a screwdriver to get the accumulation of carbon off and then I found that the inner pipe had perforated. I cannot imagine trying to do an efficient cleaning job without first removing both the elbow and hose.

If you do remove it, remember to get a new gasket as the old one will almost certainly not be reusable.

Hope this helps.
 
I remove the unit from the manifold. The hose was stuck but it wass pretty easy to separate working a large flat screwdriver around the hose.

I soaked the unit in hydrochloric acid ....... although I would prefer to use phosphoric acid as HCl is too agressive on the cast iron. It came out clean after about 20 minutes.

These elbows have a history of cracking or corroding through, so it would be best to have a replacement handy.
 
We inspect our annually now after the first failed. Tend to run engine to warm hose first. Then unbolt manifold from engine. Good clean with screwdriver and wire brush to inspect joints. Lucky this year as gasket came off complete. reassemble run engine check again after a few hours running for leaks.
 
The unit on the 3YM is a stainless fabrication.

I suspect the weld on one side is leaking, and the list price for a replacement is a ridiculous £153.

The engine has done 1323 hrs from new, but cleaning the exhaust elbow is specified in the Yanmar handbook at 1000 hrs.

Thanks for the feedback
 
exhaust pipe

Hi,take a look at my albums and you will see a solution to your problem.I presume your outer pipe is in tact ,so you just need a new inner one. You will need to bring it to a welder to make one and cut out the older one. They might be able to repair it.The one in the album was for a yanmar2gmf.
 
To add to the other posts there is a Yanmar sealant called Three Bond they recommend for the gasket.

Ours were perforated at 1000 hours and I had them welded up but was advised it could not be done again, so we replaced them recently - not cheap as has been said.
 
charles_reed said:
The unit on the 3YM is a stainless fabrication.

I suspect the weld on one side is leaking, and the list price for a replacement is a ridiculous £153.

The engine has done 1323 hrs from new, but cleaning the exhaust elbow is specified in the Yanmar handbook at 1000 hrs.

Thanks for the feedback
Click to expand...

You're lucky - the price for the non SS version on the 2/3GMFs is £180+!!
 
Scarboroughsloop said:
You think that's bad? Mine needs a high rise elbow......Just shy of £500 for that!!!!!
Click to expand...

Well I know lots of SS fab shops at home in the UK,and guess I can get one made for £30-40 at the outside, in 316.

I'll take advice from Soton Uni engg dept on the best material though.

It appears the exhaust-elbow problem is a known fault with the 3YM series.

Perhaps a little leaning by Trading Standards on UK distributors would not be amiss?
The quoted prices are a total rip-off.
 
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