Crankcase breather pressue

[NormSail350]

Hi all,

It has been a while since I have posted a question, generally because well, I have not had any major issues other than just never ending maintenance that I found that I just enjoy when I cannot be sailing. But I have a question. I took my air filter off to clean it, I still have the original air filter with the wire mesh stuf inside. (I removed and cleaned with diesel fuel). However, I have noticed that I have little or no crakcase pressure from the breather tube that leads back into the air filter. I never really noticed how much pressure there was over the last few years that I have owned the boat, but there was always some little bit of oily residue dripping onto the air filter. Just a little, bit that I believe is absolutely normal, but this seems to have stopped or is very minimal and I really don't feel much pressure out of the tube when the engine is running. I replaced the breather tube (old one was a little gummy and had some black gook in it), I pulled the crankcase cover to inspect (clean as a whistle) including the wire mesh screen inside the little cage in the top of the crankcase cover. I don't see any valves (like a PCV valve on a gasoline car engine) on our M35B's.

Engine seems to be running fine, but no noticeable pressure out of the tube (and the new tube was bone dry after running for a few hours yesterday).

Normal? Do you have perceivable pressure (puffs of crankcase gases) out the tube? Thoughts/comments?

[wolfe10]

Easy to verify that there is no restriction in the tube. Remove it from the air filter and blow into it. Should be zero resistance.

If you have a foam air filter, a good idea to replace it every couple of years. I have seen them designate and the pieces sucked into the engine.

[ElizabethG]

Brett is spot on...

That foam will basically rot over time. Mine crumbled in my hand.

Per a recommendation from Ken Krawford a few years ago, I replaced mine with a K & N filter.

Bill

[Monty]

do you have a model number or equivalent for the K&N filter you used on the 350?

[ElizabethG]

Hi Steve,

I ordered mine from eBay back in July of 2021.

It was a K&N RU-2450 Universal Clamp-On Air Filter. They are not cheap at about $60

Looks like Amazon has them as well.

Bill