Oil fouled air cleaner

[osprey877]

The PCV system in my circa 80's pathfinder 4 cyl diesel (a marinized VW golf engine) consists of a 1/2" breather hose running from the top of the valve cover to the air intake. There is a baffle at the valve cover fitting (and perhaps some mesh filter? I haven't had the valve cover off so can't say for sure).

There is enough blow-by now that the air filter is being fouled with oil and needs cleaning or replacing after a hundred hours or so. The engine otherwise runs fine and doesn't burn oil or coolant and I don't want to rebuild it and hopefully reduce the blow-by.

What I would like to do is introduce some sort of filter or oil separator into the breather hose that would take the oil out of air before it gets to the air filter. I have checked google, Lordco, Napa etc. and nobody seems to have such an animal. Any suggestions? I have looked at a oil filler cap with a small filter on top to which a PCV valve can be inserted, but the filter looks very small and llikely to plug up quickly.

Any suggestions appreciated.

[Uncle Bob]

I do believe that you are looking for an oil catch can, flea bay has thousands of them, in a range of qualities and prices.

[osprey877]

Originally Posted by Uncle Bob

I do believe that you are looking for an oil catch can, flea bay has thousands of them, in a range of qualities and prices.

I think you may be right. Thanks.
The ones I can find on Ebay all seem designed for high performance cars. Does anybody know if there is a marine version? Does anybody have any experience using one of these catch cans on their boat??

[Compass790]

I dont know that engine but is it possible to replumb the breather so it enters air intake after the air-cleaner? Thats how its plumbed on my Yanmar which has savage blowby. Or else change your air filter to an oiled foam type. I'm assuming it has a paper type element.

[TeddyDiver]

Or you can chance the airfilter to a wet filter

[Uncle Bob]

Originally Posted by osprey877

I think you may be right. Thanks.
The ones I can find on Ebay all seem designed for high performance cars. Does anybody know if there is a marine version? Does anybody have any experience using one of these catch cans on their boat??

Marine means expensive. The heavy duty plastic versions can be fitted to any engine relatively easily, without the marine price tag.
Or as suggested re-plumb the vent to after the filter. The only downside to this is that any oily residue will end up coating the inlet tract of the engine, whereas a catch can will eliminate most of it.

[Compass790]

Originally Posted by Uncle Bob

Marine means expensive. The heavy duty plastic versions can be fitted to any engine relatively easily, without the marine price tag.
Or as suggested re-plumb the vent to after the filter. The only downside to this is that any oily residue will end up coating the inlet tract of the engine, whereas a catch can will eliminate most of it.

Oily residue in air intake doesnt seem to be an issue in my YSM8 & as I said it has savage blowby but you may save oil with the catch-can. I cant comment on that as have never used one or heard of them till just now. Learn something new everyday but I probably forget 2 things

[Three Sisters]

And further along the intake path are your intake valve stems. Introducing an oily air charge at this juncture equates to an accumulation of a sooty hard crust at the intake valve. The next stop is the combustion chamber and piston tops. So the whole deal becomes progressive and unhealthy for your engine.

You would be able to build your own if so inclined.

[Compass790]

Originally Posted by Three Sisters

And further along the intake path are your intake valve stems. Introducing an oily air charge at this juncture equates to an accumulation of a sooty hard crust at the intake valve. The next stop is the combustion chamber and piston tops. So the whole deal becomes progressive and unhealthy for your engine.

You would be able to build your own if so inclined.

Not so sure about that, cant see any difference with whats occuring & a 2 stroke engine which has oil in the fuel or squirted into air intake. Some truck operators mix filtered used engine oil in their diesel fuel.In some ways it may be an advantage to have added lubrication but granted probably increases carbon buildup

[osprey877]

Originally Posted by Uncle Bob

I do believe that you are looking for an oil catch can, flea bay has thousands of them, in a range of qualities and prices.

I am leaning towards making one. Most of the car versions have a 1/4"inlet and won't handle the volume of air from my high compression diesel. The large capacity ones are $2-300.00 which seems excessive.

The easiest way to make one appears to be to use an inline fuel filter with a paper cartridge. I assume if it can water from fuel it can separate oil from air??

Again, anybody used and/or made/bought one of these???

[Three Sisters]

The continued fouling on the valve components such as guides and sealing surfaces, again, is not healthy for the engine and can lead to altered valve duration events and the dreaded stuck valve.

[Aeolus6]

After 31 years and 2 VW diesel marine conversions, the second of which is still going strong at 11,000 hours the following.

Both engines burped a bit of oil vapor from the crank case breather hose onto the air filter after 100 or so hours, leaving a 4" oil spot, but never coated the whole air filter.

The VW USA engine rebuilder in Lakefield, Illinois advised me not to modify the breather hose, stating VW diesels have some crankcase back pressure under normal operation and that the enlarged aluminum oil pan employed with the Pathfinder Marine Conversion may make matters a bit worse.

Based on my experience, I don't think I'd worry too much.

[a64pilot]

If you insert a catch can into the existing hose, you are not really modifying it.
All a catch can is is a can with two hose connections on the top, upon entering any liquid will drop to the bottom of the can and air and vapor will continue on thru.
An oil separator is a little more complex, usually it's just a labyrinth that the oil vapor goes thru, but sometimes its nothing more than a catch can with steel wool in it.

Excessive blow by is of course an indicator of possibly worn rings or glazed cylinder walls.

[Kita]

Originally Posted by Compass790

I dont know that engine but is it possible to replumb the breather so it enters air intake after the air-cleaner? Thats how its plumbed on my Yanmar which has savage blowby. Or else change your air filter to an oiled foam type. I'm assuming it has a paper type element.

Compass got it right,connect the pcv hose coming out of valve cover & plum it into intake & that works. ...just make sure it's big enough. .they do that with cars all day

[topmast]

I remember something about those engines running away with own lube oil. Connection? Had a 671 with extreme blowby Ran hose down to 5 gal pail. switched pails when full and just poured it back in the crank . Haywire but no big deal and worked until I could rebuild.