I have the same on my 1996 #366
Rather than a woven sleeve, mine has a fibeglass woven “wrap” of 2” wide tape wound around it.
When I bought the boat I could see some rust staining on the exit side so I unwound the wrap and the elbow looked awful!
I unbolted it and the good news was that internally it looked vey good. No sooting up either.
I used a wire brush and it cleaned up really well, so the poor appearance was just surface corrosion. The riser is stainless .
I suspected a tiny crack may have developed where the water inlet joined the main exhaust tube so had that rewelded for a couple of beers!
All now good
However I too struggled to find a replacement (especially as I’m not in the USA) and wondered if the other type would be suitable. In the end, had the repair not worked, I was going to get a local fabricator/welder to make me a replacement.
I believe the wrap is simply insulation to stop damaging levels of heat until the water gets injected.
I actually think it a simpler and more elegant design that the other type, with less to cause problems
Hope that’s useful
Sent from my iPad
> On 24 Mar 2021, at 21:33, Dennis Cookson <den...@cooksons.net
> I am thinking about replacing, or at least inspecting, the exhaust elbow on our 1999 Yanmar 3GM30F as its age and condition are unknown. It seems to be a non-standard construction, unlike any Yanmar part I can find, with a U-shaped riser which is fully insulated with a woven thermal sleeve of unknown material, possibly fibreglass.