Don,
Earlier M25 engines had the crankcase breather tubes simply directed down below the engine. Later engines re-routed the breather tube to a spot near the air filter, so that the oily fumes are sucked into the engine when it is running. I was planning to do that myself (I have an '87 M25XP), until I talked to a Westerbeke/Universal rep at a boatshow. One of the "problems" with routing the breather hose to a spot near the air filter is that the oil fumes (from the crankcase) tend to get the air filter dirty at a faster rate. Instead, at the suggestion of the W/U rep, I took the intake manifold off, and drilled and tapped a hole for an elbow fitting. To that fitting I attached the other end of the breather tube. Now the oily air is sucked directly into the engine and bypasses the air filter. It has worked very well that way for the past 10 years or so. Others have simply attached their breather tubes to a spot near the air filter, and others have attached fittings to the air filter housing, all with good results. Hope this helps.

An early suggestion on our C34 website material was to simply put the end of the breather hose in an old beer can with foam inside of it to absorb the effluent. I did it one better, I stuck it into an Excedrin plastic bottle, figuring the beer would come earlier anyway! I've "had" to replace at least 5 Excedrin plastic green bottles in the last five years, but we have had no oil spills on the deck of the engine compartment. We did, however, purchase the newer air intake kit. I have yet to reroute the breather hose over to the starboard side to the air intake of the engine. It works just fine, and we have plenty of old empty Excedrin bottles - I pick 'em up from friends whenever I can.:)

I've routed the hose to the air filter but use an auto filter to run it thru so the crud doesn't coat the boats filter with oil. A lot of 70s and 80s cars had the pvc hose routed to the air cleaner via a small filter that passed thru a round hole in the side of the air filter housing. I've attached one of these to my boats air cleaner and attached the breather hose to it. Works great.

Bob Uehlein
Island Time C36 #424
Charlevoix, MI