Exhaust problem - Any Advice?

Created by doina. Last modified on 2006-04-20 10:07:08
Topic: Equipment

Hi, I would like to explain a problem that we have and from which I don't find a definitive correction.

We have an HR42 1989. We have replaced the original engine "MD31" for an "TAMD31". The exhaust hose is much larger than the original one. So we have to modify the exhaust design. It comes out from the engine with a reducer from 90mm to 75mm, then go to a waterlock, from the waterlock we made a loop right there, in the locker above and come back in the engine room. We also have installed a check valve. From there, we go to the exhaust connector on the stern port side right above the water line (original place).

Our problem is that: when the boat speeds up, the boat wave brings the exhaust exit way under the water and starts building back pressure in the system. After 2200RPM, we have reached the back pressure limit specified by Volvo.

To solve the problem, we think to bring the exhaust ahead on the starboard side near the bulkhead between the head and the master cabin, as high as possible. This will shorten the exhaust line length and hopefully it will keep the exit above the water when running under engine.

All comments will be appreciated before we make any modification.

Guy

S/Y BlueTang HR42

nicodesautels@hotmail.com