Yanmar Ysm 12 breather baffle gauze

[Alan1958]

Hi can anyone help with this issue. My engine is getting oil though the breather hose into the air intake. I removed baffle plate etc and found that a gauze was missing? I have tried to find information or images of this part but no success anyone know what size or where I can get a replacement?

Thanks in advance

Alan

[sailormed]

"My engine is getting oil though the breather hose into the air intake".....What is the problem?

[Alan1958]

After 20mins starts to smoke at first thought it was oil though the piston rings or Valves but a fellow boat with lots of boat engines experience told me to check how much oil getting past the baffle into intake which after 20 mins is a lot. In the past I have had the engine run away more than once. It starts first time no issues runs for as I say 20 mins then starts smoking and the tone changes if I left it longer it go wild.

Thanks alan

[Alan1958]

Gauze should be behind this small plate bulge on the main plate?

[Mike Banks]

I do not know about the Yanmar engine--but I once had an engine with a similar oil fumes condenser-recovery system that was allowing oil into the inlet manifold. There was a series of metal plates designed to condense oil vapour and to allow it to drip back into the oil gallery and hence back to the sump. They become carbon coated and not comparatively cold enough to condense the oil, which is then drawn into the inlet manifold. Cleaning the plates only provided a temporary sort of solution, but for me it was just something one had to do. It was a bad design in the first place. In a few months I would have to clean it all again. It was not a gauze though--a pack of metal plates with a thin spacer between each so that the oil-air mixture could pass between them--and this is what blocks up with carbon and sludge.

Wire brush and petrol or kerosene shifts it. If you have one using a coarse wire wool system, the replacement one can try is soap-less stainless steel kitchen scouring pads. Cheap as chips at any supermarket. Throw away when dirty and replace with more of the same, but be sure they can not be sucked into the engine. They HAVE to have a stainless steel gauze baffle to prevent this. Mine came from a camping toaster.



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[Compass790]

Yea what Mike Banks said, go with the s.s. wire scouring pad. Yanmar would probably make you buy a new block. I'll look at my spare YSB8 block & see if it has one on it if you want the genuine part. Might take a day or 2 to get to it tho.

[Uncle Bob]

Originally Posted by Alan1958

After 20mins starts to smoke at first thought it was oil though the piston rings or Valves but a fellow boat with lots of boat engines experience told me to check how much oil getting past the baffle into intake which after 20 mins is a lot. In the past I have had the engine run away more than once. It starts first time no issues runs for as I say 20 mins then starts smoking and the tone changes if I left it longer it go wild.

Thanks alan

Hi, if you have enough blow by to allow the engine to run away then you have a problem. What oil do you use, is it a good quality that maintains it's viscosity at higher temps? Another thing you could consider is a catch can in the hose between the rocker cover and intake.

[Compass790]

Originally Posted by Uncle Bob

Hi, if you have enough blow by to allow the engine to run away then you have a problem. What oil do you use, is it a good quality that maintains it's viscosity at higher temps? Another thing you could consider is a catch can in the hose between the rocker cover and intake.

Yes good point you make about blowby but remember these are single cylinder engines so there is a lotta air movement as the piston goes up & down.
If the oil gets taken out of the air going into intake wether by gauze or catch can it should solve runaway problem.
Maybe he should do a leakdown or compression test as well.