Question about Breather Tube & Reed on Kohler CH18 Engine

[kruss77]

On a Kohler CH18, what does the breather tube & breather reed do? I've been getting an occasional coating of oil on my air cleaner pan around the carb opening and don't know why (assumed to be come up through the breather tube which vents into the top of the carb). I assume that the breather is like a PCV valve on a car that vents crankcase gasses back into the carb to be burned-off. But I'm getting a film of oil that has on two occasions caused the engine to stall (usually after I've mowed uphill for a period of time). The oil level is just below the full mark on the dipstick.

Can anyone shed some light on why this might be happening?

Thanks.

 

[OldMachinist]

Yes, the reed valve is like the PCV on a automoblie engine. It's possible that the reed is broken or stuck on yours allowing the oil into the air filter housing

 

[jimdiesel1]

Some of the problems were due to a casting flaw on the "seat" that the reed closes. If you check the reed and it shows an incomplete seating problem you should consult your dealer or examine the seating area for "flash" in the seat which does not allow it to close fully. Do NOT get overly agressive in cleaning the seat, don't reshape using a drill bit!

In addition there were cases of reed failures, cracking occurred and split the reed material.

Now before you get too indepth, you should do a simple check to see if you have vaccum or pressure in the crankcase. Grab a balloon and fit it tightly over the dipstick tube. Start the engine and observe the balloon, in should be drawing in. If it instead is inflating the balloon you know you have positive crankcase pressure, not good! Pull the spark plugs and inspect each side for oily deposits, if one side is wet and oily suspect a leaking head gasket {leaking compression into crankcase at the oil return passage or lifter gallery}.

If plugs look great suspect the breather reed/seat issue.

 

[Frosty2]

You can take a small filter and run the tube to that with a piece of hose. Do it all the time on motorcycles. Shhh,Don't tell the EPA.

 

[kruss77]

Well, I finally got around to inspecting/servicing the breather and reed on the Cub. The reed was fine, but the filter was in pretty bad shape, so I replaced it, reassembled everything, and hoped for the best. It worked great for 1.5 complete "mowings". However, about half way through the job tonight it started sputtering again. Upon further inspection -you guessed it: the breather tube was dripping oil. Something I forgot to mention before was that my back yard is on a bit of an incline, so I'm always either mowing down a hill or up a hill -rarely ever on perfectly flat ground. I never suspected this to be a problem before because I've mowed this way for the prior 6 seasons without a problem -until this year. Now I can't keep the oil out of the breather tube. Looks like it's time to route the breather tube away from the intake altogether.

Anyone have any other ideas?

 

[2manyrocks]

I had this problem with one of the cast iron K series kohler engines. I replaced the breather assembly with a kit and the problem stopped. The kit has a new plate, filter, etc. in it. Was cheap enough that you could try it.

 

[kruss77]

Don't suppose you recall the Kohler part number?

 

[2manyrocks]

I just did a quick search for a breather kit for the CH18. Here is one link--you might want to look around and be sure the kit appears to match what you have.

Breather Parts : Kohler Engines and Kohler Engine Parts Store, Genuine Kohler Engine Parts

 

[rallen1]

Did you ever solve your problem? If so, how?

I have a Kohler CH25 with the exact same symptoms, and like above, I mow on some fairly steep inclines. I did not have this problem when I was mowing on flat land before I moved. It is an issue because the oil contaminates the paper filter to the point I have to replace them frequently.

When I replaced a bad head gasket on one side (oil fouled plug), it solved a backfiring problem but not the oil on the carb platter problem. At that time, I opened up the breather and did not notice any defects, so reinstalled it, but perhaps i should just replace the reed and breather filter at this point.

Do I need to replace any other parts? I looked at a "kit" for the breather assembly but it didn't include the reed or filter; just the cover and gasket. Any other suggestions? Is it possible the other side has a bad head gasket letting pressure into the crankcase even though there is no oil fouling (both plugs look fine)?


I thought of two options if this doesn't work:

a. Purchasing a K & N air filter for this engine. Apparently, this filter is supposed to be oiled since it is not a paper filter. My thought is that at least it would not keep plugging up as fast, and when it did I could wash it.

b. Install an oil trap, similar to what one might use as a water trap on a compressor, routing a new tube from the breather to the trap and then back up to the carb.

I would REALLY like to know how to solve this problem. It doesn't burn oil; it just seems to blow it out the breather when I mow on my slopes. It is not overfilled.

Robert

 

[kruss77]

Yes, I solved this problem! As it turned out the oil in the breather wasn't actually causing my problem as I thought. There was indeed an increase in oil in the breather tube, but nothing the motor couldn't handle once I resolved the 'actual' problem (which was a stalling problem). In my case I had a bad FUEL PUMP that would operate fine on flat ground but as soon as I headed up a hill and put a load on the engine it just couldn't keep up. I had rebuilt the original OEM aluminum pump and therefore had eliminated it as a potential failure mode when attempting to diagnose this problem. This is why I started looking at the oil buildup in the breather tube -thinking that a large amount of oil feedback could actually be causing the stalling problem. However, my brother (and several people here and on another websites) all felt my 'stalling' problem was fuel related and had little to do with the oil in the breather. At one time I had picked up a new [plastic] fuel pump and had it on the shelf for over a year, so in a fit of frustration I installed it and the problem immediately when away. Oil in the breather wasn't causing my problem.