The tempered water lines should have antifreeze in them to prevent freezing. Are you saying that you don't heat the boat at all during the winter???
I've had 2 8v92's and 1 12v71 that blew tons of black smoke under load and all of them had a low cylinder......like 90 psi...... I've had dirty...
Have you considered doing a compression check.....or easier still, start the motor and shoot the temperatures of each exhaust port of the exhaust...
Yeah, if it's the dometic one it's easy.......they press in, but you have to carefully cut the tubing to fit (use a tubing cutter) and make them...
Also, bleed all pressure and check the air pressure in your expansion tank if you have one.
Call headhunter. They have a great customer service department. Sounds like you may have an air leak on the suction side or suction hose that's...
