Oil fouled air cleaner

[a64pilot]

Originally Posted by topmast

I remember something about those engines running away with own lube oil.

This is your worst case scenario, and it can happen, has happened.

[Kita]

Didn't really think of that but it sure could, well that would solve the reman thing! I was near a dc9 I think,big dozer...when it ran away. It was a fresh start of a rebuilt engine & it was a dozer that was donated to the school & was built in house & I think someone put the wrong fuel in cause it went to wide open immediately. The diesel class was at the other end of the complex I was in motorcycles and I heard that thing spooling up so we jumped on scooters and went to go watch. That was really something to see. A guy walked up to the intake with a box of rags and it was like a big giant chipper didn't even slow it down a bit! That was a big bad boy that went kaboom! Sounded like a military bomb. It shook the buildings near it maybe for a block it was Unreal. You definitely don't want to let that diesel Runaway that's definitely not good or cheap

[Sailorbob8599]

I question your need for an Air Filter in a boat at all! I've yet to see dust in my boat as I would expect to find in my home. The engine room, being closed off from all other parts of the boat with the exception of the Bilge, is spotlessly clean. I can run my hands over any part of the engine and its compartment and not find dust contamination of any kind . . . So I guess the only purpose or value of having an Air Filter on a boat might be to keep Seagulls out of the engine?
Personally, I would ditch the Air Filter . . . end of problem.

[osprey877]

I still haven't heard from anybody that has actually ever seen or used a catch can or similar on a marine diesel.

Aelous6: Sorry, but I can't follow your response. Is the "bit of back pressure" good or bad?? Does the larger sump increase or decrease the backpressure, and is this a good or a bad thing? What effect on the amount of backpressure would adding a catch-can have? The inline fuel filters etc are sealed units so it seems to me that whatever the pressure at the valve cover end is will be the same at the air cleaner end provided the hose size at each end is the same?

[Cheechako]

You shouldn't have excessive blow by. I wonder if valve stem seals could be doing that? Many marine diesels have no paper air filter, you could eliminate that if you have one. Then you'll just be burning the blow by.

[a64pilot]

Back pressure, bad.
Automobiles since the last 50 yrs or so have had PCV valves that actually make a slightly negative pressure in the crankcase, that is what you want and likely what you now have.
Many, many Commercial Diesels just have an open tube that vents to atmosphere which works fine, but not in an enclosed space though.

[knockabout]

a small plastic oil bottle of the type you buy oil in placed lower than your motor / run your crank case vent hose to the oil bottle then run a hose from the oil bottle to the air cleaner /a piece of copper pipe same size as the inside of your crank case breather hose inserted in the top of the oil bottle that reaches almost to the bottom and sealed where it's poked through the bottle / the second hose connected to a short piece of copper pipe inserted in the oil bottle lid approximately 40mm long (only drawing vapour from the top of the bottle) /

[Barney21]

Originally Posted by 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.

band aid won't fix the problem , I suggest you do leak down test . I think you are blowing diesel back up the intake manifold. This can be caused by valve stem wear or the pil seals on the valve stems ate perished. You don't say if engine is turbo charged , that could cause oil / diesel to get to the engine crank case thereby back through to the air cleaner.

[osprey877]

Originally Posted by Barney21

band aid won't fix the problem , I suggest you do leak down test . I think you are blowing diesel back up the intake manifold. This can be caused by valve stem wear or the pil seals on the valve stems ate perished. You don't say if engine is turbo charged , that could cause oil / diesel to get to the engine crank case thereby back through to the air cleaner.

Engine is not turbocharged. Diesel is not blowing back up the intake manifold. I know this because the oil staining is in the middle of the filter where the breather hose enters, not on the ends where the intake manifold draws its air from.

[01kiwijohn]

UH, Uh, Uh......you run a very real risk of having the engine run away on you if you do this. A diesel will quite happily run out of control burning crankcase oil and fumes. Be very careful. If it does run away, the only way to stop it will be to block off the air supply; quickly!

[Kita]

Originally Posted by 01kiwijohn

UH, Uh, Uh......you run a very real risk of having the engine run away on you if you do this. A diesel will quite happily run out of control burning crankcase oil and fumes. Be very careful. If it does run away, the only way to stop it will be to block off the air supply; quickly!

Yes,quite right,if run to intake, bad idea.where the line comes into air cleaner, reposition it to where it comes in from bottom of air cleaner instead of pointing right at the filter that way it's not hitting the air filter and it's still on the correct side of throttle valve..I had one like that once

[osprey877]

Originally Posted by 01kiwijohn

UH, Uh, Uh......you run a very real risk of having the engine run away on you if you do this. A diesel will quite happily run out of control burning crankcase oil and fumes. Be very careful. If it does run away, the only way to stop it will be to block off the air supply; quickly!

If I do this?? I'm trying to f ix an existing problem by removing the oil from the blowby, not adding more oil to it!

I've decided I'm going to make my own catchcan. I'll post some pics when its done.

[sartorst]

Sound like you are making a problem where a problem does not exist ALL engines run the crankcase vapor back into the engine to be burnt there is no problem with this that is the perfect way of disposing of the oil vapor , fumes ,moisture, no collection needed ! I might would route it inside the filter so that it does not wet the filter if it is that bad but all engines have some blow-by no worry > Don't compare a gas engine to a diesel a gas engine has vacuum in the intake and has a pcv valve to stop a back fire from blowing the oil pan off !

[UNCIVILIZED]

I wonder if K&N might be able to assist with this issue, given their specialization in engine air filters?

[Suijin]

I just made a few days ago a catch can out of a 2" PVC "T" piece, some bushings and fittings, and a stainless steel scrubby pad. It's not a complicated device.



Picture is displaying sideways. It will be mounted vertically, plug at bottom, on a bulkhead. However, PVC is only rated to 140 degrees so I'm going to check this frequently after installation to confirm it can handle the vapor temp while I see if it's doing anything.

On Amazon you can find dozens of aftermarket catch cans, some pretty fancy, but non evidently engineered for marine/saltwater applications. I wanted to see what it did for me with my ghetto version before investing in something more...professional.

Mainsail posted a photo not so long ago with a breather hose entering the bottom of a K&N so it does not spray residue directly on the filter element.