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? 

 

 

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