M-25 Crankcase vent?

[Russ Williams]

My 1984 C-36 has the 3 cylinder M25 universal diesel. The crankcase vents to a thing that looks like an oil filter via a hose from the top of the valve cover. My engine owners manual doesnt show any such thing. Is this typical for this engine or has mine been rigged??RussS/V Four Sail

 

[Mike s/v Chute the Breeze]

PVC

I'm just guessing but usually they have positive crankcase vent (pvc) so it should be feeding back to the air intake somewhere.. fumes get sucked back into the engine and reburned? Mike WD9EOU

 

[Mike s/v Chute the Breeze]

PCV

sorry my eyeballs are crossed this morning PCV!!

 

[Gordon S.]

Venting Vapors

Russ,I have had the annoying problem of a sooty transom on my C27 for two years.I now think that the crankcase vent on the M18 diesel, which is a hose strapped to my engine air inlet, is the culprit. It appears that some oil vapor escapes this hose, is intentionally sucked into the diesel air inlet, and deposits itself unburned on the transom as the exhaust gas swirls around. I have purchased a small air filter used on lawn mower engines and will install this on the end of said hose to trap the mist. If this works this weekend, trapping the oil mist and curing the problem, we may have the answer to what that filter-looking thing is for on your boat. Probably an owner mod. Gordon S.

 

[Rob]

Vent

I have an 87 and the vent runs through a hose to the bottom of the engine by the motor mount. The end of the hose is open and sprays a little bit of oil and Diesel gunk on the side of the motor pan. This really sucks as it makes it impossible to keep the area really clean. Perhaps the previous owner installed the filter to cure this problem. I am trying to figure a way to fix it myself.

 

[M Kolbenschlag]

crank case vent

I used to have a c30 with the same engine that I bought new in 1989. the crank case vent was as you say, open ended and aimed down into the bilge at the motor mount. Same mess. Solution was to add some hose, drill a hole in side on the air filter and stick the hose in. That ended the problem and had no noticeable impact on exhaust out the back.