Changing exhaust/wager mixing elbow. Yanmar 3jh5e. So soon?

[Oscarpop]

Our Yanmar manual says to change the exhaust mixing elbow every 2 years or 500 hours.

I understand that it can corrode inside, but 2 years seems a little much.

Do you good people stick to the 2 year change?

We are currently at 4 years and have t changed it yet. However we are coming up to our 1000 hour service and could easily add it to the (expensive )list .

Cheers

 

[westhinder]

Mine is a 3JH3E, so very similar, 16 years old. I haven't changed it since I bought the boat 5 years ago. I normally do between 150 and 200 hours per season. As far as I know, the first owner did not change it either. I spoke to my friendly Yanmar mechanic and he advised me to leave it as is.

 

[Tranona]

Take it off and inspect it. You have done a good number of hours - 250 a year suggests you run it well. The elbows gum up and corrode if engines are lightly used and not run for long hours on good load. So doubt yours will give any problems.

 

[[3889]]

My 3ym30 elbow, with the same Yanmar service routine, has just failed after 900 hrs / 9yrs. I would suggest either carrying a spare elbow + gasket on board or being prepared to weld the flange/pipe joint. If the elbow fails in the normal way it is not catastrophic - a drip will develop from a hairline crack - so keep an eye out for water in the engine bay.

 

[vyv_cox]

Contrary to popular advice I believe the failure mode to be thermal fatigue. Repeated heating and cooling creates large stresses in the welded joint between metals of differing thickness. The result is a crack that allows water to creep out. In most cases there is plenty of warning that serious failure is imminent and it is not a difficult job to replace it, so carrying a spare and gasket is probably sufficient. Does no harm to inspect it but you will need the new gasket when you replace it. Look out for unusual water in the bilge and signs of corrosion beneath the manifold.

 

[Oscarpop]

Thank you all. Virtual beer all round.
Real beer if you by any chance in Falmouth harbour Antigua over the net few days.

Cheers