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Kohler CH20: Bad Breather Filter?


jbrukardt

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So, some of you may remember my last thread where i learned thanks to all your excellent help how to pull the engine from my Sunstar and redo the head gaskets. Thank you for that.

Now you may all remember the original cause for doing that, before i threw a valve seat. It was hard starts, oil foiled plugs, and overheating due to all of the above. After my rebuild, i took the tractor out for half an hour of mowing to test it out... and upon stopping to blow everything out before moving it into the garage... Voila, I have the same problem as before. My plugs are terribly foiled with oil and it wont start again. This will not do.

So outside of my rings being completely and utterly shot, which is still a possibility, I think I may have my root cause.

A bad breather filter/gasket. I think im spewing oil contaminated air back into the crankcase, causing overpressure, forcing oil past the rings, and contaminating my combustion chambers (equally on both sides). Similar to how a bad PCV valve on a car can do that.

My reasons for believing that are as follows:

1) Contaminated air filter with oil spray

2) Small puddle of oil (1 tsp'ish) sitting on the mounting plate for the air filter

3) upon pull the carb and linkages, and the breather filter plate, both sides of the gasket and the small filter are soaked with oil, indicating oil is getting where it should not be.

Gasket honestly looked ok, but symptoms indicated it was not. The 10mm bolts that hold the breather plate on seemed awfully loose to me. I know theyre only supposed to be torqued to 65 inch pounds, but they came off with almost no effort whatsoever.

So with no further ado, ive order a new style breather plate, and a new gasket, and we'll see if that solves my oil fouling problem. Pictures below.

What do you guys think?

Gasket

9054578photo_1_.jpg

before gasket remover to clean it up nice and a good soak for the whole channel in seafoam to make sure none of the galleys were plugged

1576343photo_1_.jpg

Also, how the heck do you remove this part of the linkage. Its got a tiny little cotter pin the base and a tightening screw. But when you remove both those, and try to pull it off, the whole pin just raises out of its socket, and loses its motion restriction.

8228456photo_1_.jpg

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Have you been able to do a compression test on the engine? Typically you should have 180PSI if it's in real good shape, down to 140ish if its getting tired.

I don't think the breather filter would have too much effect on the oil coming through, but if it is leaking from the pressurized outer channel into the breather compartment, that could definitely cause it. How does your breather valve/reed look? Is it sealing completely?

The Oil in your air filter indicates to me that it is coming through the breather. I would think replacing the gasket should solve your problem. Of the breather covers I've taken off, usually the gasket rips in half as it's stuck to both halves, yours looks oily around the outside, kind of like the cover was just sitting on there not sealing very good. Most likely because of the loose bolts.

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breather filter reed looked good, replacing it anyway, but it looked good.

The pressurized outer channel was almost definitely getting into the breather compartment. The filter was black and soaked in oil.

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Also found a crack in my breather tube. Gonna go to the auto store and see if they have anything of appropriate size i can replace that with

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Mine is around 145 - 150 on compression in my Sovereign 18, doesn't use oil in a 50 hour oil change interval and run like a top. Where are these tired engine compression figures etched in stone published? Just curious.

One thing you definitely need to do once you get it sorted out is remove the oil and dirt accumulation from the motor. It will run cooler. I run an oil cooler on both my CH an CV 20. Some people will say they are not necessary but they made them for a reason and can be had cheap on eBay. Kohler states they will run 30 to 40 degrees cooler with the cooler.

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Ray, those numbers certainly aren't etched in stone. That's why I said typically, and 'getting tired' However, I have a new CH23, it has 175PSI, a CH20 with 40 hrs with 185PSI, and a CH20 with 495hrs and 180PSI. Now, the older engines, I have one with 1400hrs and 160psi, and several with unknown hours have anywhere from 150psi down to 125. They all still run good, however it is noticeable when under a heavy load the lower compression engines don't perform the same. I haven't run into an oil burner yet.

I also agree on the oil cooler, I have on my CH23 in my Agco 1920 and wouldn't mind finding a few more.

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Interesting that was the compression on my CH a year and a half ago. Makes me want to check the CV 20 in my Prestige.

Yesterday I was mowing a 1/2 acre lot that was in the 1 - 1-1/2 foot range and the CH20 ran great.

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quote:Originally posted by RayS

Interesting that was the compression on my CH a year and a half ago. Makes me want to check the CV 20 in my Prestige.Yesterday I was mowing a 1/2 acre lot that was in the 1 - 1-1/2 foot range and the CH20 ran great.


id="quote">
id="quote">Before i oil foiled again, thats about equivalent to what i was doing. Foot an a half or so, high mow (hydro deck as high as it would go). Ran like a champ, not a single bog down.Its a very powerful motor.
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