I just finished, actually I am installing the new mixing elbow
tomorrow, the same exercise on my 4JH2E. I talked to a lot of people about the Yanmar
mixing elbow "issue."
Yanmar offers a $250 elbow for my 4JH2E that the Yanmar dealer wanted me to use. The problem was that, on our Caliber 40, the exhaust
manifold outlet to the mixing elbow is only 5" above the water
level in the water lift muffler
. AYBC requires the bottom of the mixing elbow turn to be 10.5" ABOVE the water level.
The $550 Yanmar elbow for a 4JH2 engine (Yanmar Part # 12947013540) provides the necessary additional 5.5" rise so now the bottom of the U-turn in our mixing elbow is 11" above the waterline.
I talked with several local mechanics, welders, and machinists about a custom or semi-custom elbow. The cost, in every case, was far more than using the stock $550 Yanmar elbow.
Two Yanmar owners I talked to had custom stainless elbows installed to replace old leaking Yanmar elbows. They were pleased but spent way more than I did and their machinists did NOT expect those custom elbows to last any longer than the stock Yanmar elbow.
My elbow was not leaking but I did replace it after 20 years and 2,900 hours.
My Yanmar parts
manual and factory service
manual show the elbow I chose can be used on any 4JH2 engine, up to and including the TE.
Hope this helps.