Perkins 4.108 Exhaust Mixing Elbow

[_Jason_]

Hello all! We had a blow out on the threaded flange leading to the mixing elbow due to corrosion. The motor is rebuilt, and the mixing elbow doesn't look OEM (see photo). The issue was a mild steel flange connected to a stainless elbow, and the weak link finally corroded and gave way. I've since found a stainless OEM replicate mixing elbow from HDI Marine out west (https://hdimarine.net/product/p4bow-cast-stainless-steel-mixing-elbow/), but the water inlet barb is for 1-1/4" hose and the exit from the Bowman heat exchanger is 1". This seems like a simple task to step up the size, but when incorporating a vent loop and the available space above/adjacent to engine, we are finding difficulty to make acceptable bends in the hose without kinking. Anyone with experience replacing the exhaust mixing elbow on the Perkins? And a clever way to incorporate a vented loop in the space. Any feedback is welcome!

p.s. the original hose from exchanger to elbow had a tall loop with a one way valve prior to the mixing elbow. That doesn't seem like it would stop a siphon from filling up the exhaust and flooding the engine. Not sure the original thought, or perhaps they couldn't fit the vented loop either!

 

[terry_thatcher]

My engineer installed such a vented loop in my new Beta install. He seemed to think it was a good precaution, particularly if you are motor sailing. Very important is the size of the water lift muffler. My vessel ran a Perkins, however, without a vented loop with no problems. And evidently Morgan also spec'd the right muffler. But after 44 years, its glass was deteriorated. I used the same size. The Entek folks said the spec was to have a muffler whose design capacity would accept a full exhaust line draining into it. The Morgans have a pretty long exhaust run, as you know.