The exhaust port in the mixing elbow of our Yanmar 2GM20F was 99% blocked, yet the engine was still running relatively well. She was blowing a little smoke, and this past spring the mechanic said that we should check the exhaust port because the rpm were low at full throttle. Eight months later.......
We removed the exhaust elbow from the engine block with the mixing elbow still attached. The four bolts came out very easily, but getting the hose off was much tougher. We used a hack saw to cut the rubber hose and dikes to snip the reinforcing wires embedded in the hose.
See the small hole just to the right of the thin metal rod. It’s about the size of an aspirin. We’ll try to chisel away the carbon so we don’t have to buy a new mixing elbow (~$185 from yanmar), but I’m not counting on it.
We sprayed with PB-Blaster and used a vise and a pipe wrench to remove the mixing elbow from the exhaust elbow. But we couldn’t subsequently unscrew the “joint”, (the double threaded pipe that connects the two elbows together), from the exhaust elbow. I plan to reuse the exhaust elbow, and now by necessity, the joint. I assume the joint can be reused…. I’ll ask the parts guy at the marina next week when I pick up the mixing elbow and the gasket for bolting the exhaust elbow to the engine block.
Can we reuse the joint? Or is it tapered and not reusable?
What gasket dressing should we use, if any?
We’ll use Teflon tape and Teflon paste when reassembling.