Patrick;
The PO installed the new Universal M35B using the basic exhaust elbow available from Westerbeke instead of a riser, which put the high point of the exhaust 6 to 8 inches above the waterline, to port of the centerline of the boat. Because of the geography aft of the engine on a 38 MK2, the horizontal Hydra Hush muffler was installed on the starboard side of the transmission, near the waterline. That gave an angle of 30 degrees or less from horizontal to the hose that crossed from the exhaust elbow to the muffler (behind the heat exchanger). Aft of the muffler the 2” hose from the exhaust was reduced to the original 1 ½” hose used on the original A4 (increasing back pressure and probably resulting in more water staying in the muffler) and the hose was just laid in the bilge on the way back to the original 1 ½” through hull in the transom – maybe 8” to 10” above the water line and less so when the boat squatted under power. So the high point of the system was pretty much the exhaust through hull and the hose was undersized, but apparently adequate. When under power the exhaust sprayed out of the through hull like a rooster tail; I corrected that with a rubber elbow that redirected the spray downward, but didn’t really think about why it was happening. In retrospect, when the engine was shut off all the water in the hose aft of the muffler drained back into the muffler. Then when sailing with high port heel, the water drained back from the muffler to the exhaust manifold. So long as I started the engine after sailing (which is normal) the exhaust pressure cleared the water out of the manifold. That arrangement worked for 5 years and about 400 engine hours, until I put the boat into a slip without the engine, and left it sit for a couple of months. That let the water in the manifold seep into the cylinders and rust the rings to the cylinder walls. The replacement system is what Westerbeke/Universal recommends in the installation manual – and a bit more when space permitted. After 9 years and about 900 hours no problems so far – and I don’t need to put up with the rooster tail getting the cockpit wet when motoring downwind. Rick Brass Washington, NC From: CnC-List [mailto:cnc-list-boun...@cnc-list.com] On Behalf Of Patrick Davin via CnC-List Sent: Tuesday, January 30, 2018 3:54 PM To: cnc-list@cnc-list.com Cc: Patrick Davin <jda...@gmail.com> Subject: Re: Stus-List Vented loop for engine above exhaust elbow? Rick, that's the sort of nightmare story I'm hoping to avoid! When you say corners were cut "on the exhaust elbow, hose routing, and the siphon break" do you mean the prior engine had those things installed in a poor manner, or that a siphon break wasn't installed?
_______________________________________________ Thanks everyone for supporting this list with your contributions. Each and every one is greatly appreciated. If you want to support the list - use PayPal to send contribution -- https://www.paypal.me/stumurray
