Kohler 20hp command

[John2189 503]

I took the air filter out to clean it and the where it mounts is filled with a thick film oil, had to wipe it up with a rag. It’s a horizontal shaft. It has a hose coming from valve cover. It doesn’t smoke. Sometimes starts hard at operating temperature. 
could I have a blown head gasket?

 

john

[Maxwell-8 4,366]

Or the pcv valve is going bad...

 

An high hour engine?

[John2189 503]

14 minutes ago, Maxwell-8 said:

Or the pcv valve is going bad...

 

An high hour engine?

744 hrs. 
 

how do you check pvc alve?

[Snoopy11 5,717]

51 minutes ago, John2189 said:

744 hrs. 
 

how do you check pvc alve?

Oil blowing out is a bad sign. Might have some bad rings. Hard to start follows along that line. Head gasket would be the easiest fix, (I say easy... easier than rings...)...

 

Are you 100% sure that the crankcase is not overfilled with oil? Just trying to discount the obvious, buddy!

 

Don

[JoeM 7,923]

I have several of those CH20 and CH22's, 300 hours to over a 1000 and the all have oil in the air cleaner from the crankcase vent. Not a lot but there is a visible film.

 

Hard starting,  you mean it cranks a lot? 

 

I found cranking is a usually a fuel issue.

[John2189 503]

17 minutes ago, JoeM said:

I have several of those CH20 and CH22's, 300 hours to over a 1000 and the all have oil in the air cleaner from the crankcase vent. Not a lot but there is a visible film.

 

Hard starting,  you mean it cranks a lot? 

 

I found cranking is a usually a fuel issue.

Ok there is a pretty thick coating of oil. 
 

yes it cranks a lot. When it does start, it misses bad and blueish black smoke.  Then it smooths out and runs ok. 

[JoeM 7,923]

3 hours ago, John2189 said:

yes it cranks a lot. When it does start, it misses bad and blueish black smoke.  Then it smooths out and runs ok.

What makes it start? A little choke? What is the throttle position? 

 

Some are different then others, I usually start hot 3/4 throttle, no choke. I let her spin 4 or 5 times, wait a few then try again. 

[John2189 503]

2 hours ago, JoeM said:

What makes it start? A little choke? What is the throttle position? 

 

Some are different then others, I usually start hot 3/4 throttle, no choke. I let her spin 4 or 5 times, wait a few then try again. 

Full throttle no choke.
 At idle, it ran battery dead 
before when hot it would start right up at idle  

 

it starts cold at idle about 1/2 choke 

[JoeM 7,923]

Nothing glaring there, Sounds like you have paid attention to what is going on. 

 

I would pull the plugs after running a while and look at the quality of burn. 

 

To make sure the coils are firing good,  another easy test while you have the plugs out, have them connected to the wire and plug against the frame. Do this with the engine hot crank it over and observe the spark quality. 

 

 As far as further diagnostics, my next step would be a leak down test. I prefer that to compression. compression is okayish but leak down is a good indicator.

 

Being an overhead valve machine, a  blown head gasket would be problems hot or cold. 

 

Incase you don't have it i attached a Kohler Service Manual, lots of good info, I think troubleshooting is on page 17

 

Kohler CH18-CH25 SM _2469006 RevC.pdf

 

 

 

[John2189 503]

5 hours ago, JoeM said:

Nothing glaring there, Sounds like you have paid attention to what is going on. 

 

I would pull the plugs after running a while and look at the quality of burn. 

 

To make sure the coils are firing good,  another easy test while you have the plugs out, have them connected to the wire and plug against the frame. Do this with the engine hot crank it over and observe the spark quality. 

 

 As far as further diagnostics, my next step would be a leak down test. I prefer that to compression. compression is okayish but leak down is a good indicator.

 

Being an overhead valve machine, a  blown head gasket would be problems hot or cold. 

 

Incase you don't have it i attached a Kohler Service Manual, lots of good info, I think troubleshooting is on page 17

 

Kohler CH18-CH25 SM _2469006 RevC.pdf 3.04 MB · 0 downloads

 

 

 

Thanks for the help and the manual. Never thought of a bad or weak coil. 

[John2189 503]

On 10/9/2021 at 11:37 AM, Snoopy11 said:

Oil blowing out is a bad sign. Might have some bad rings. Hard to start follows along that line. Head gasket would be the easiest fix, (I say easy... easier than rings...)...

 

Are you 100% sure that the crankcase is not overfilled with oil? Just trying to discount the obvious, buddy!

 

Don

No it is not overfull

[John2189 503]

Ok I pulled the plugs and both are dry and black    
that says it is running rich. The shutoff solenoid clicks, so I assume it is working. 
the air filter is coated with oil, so im sure it is restricting airflow. I have a new filter on order.  Im going to pull the carb then pull that plate under it and check the reed valve, I assume that is the pcv valve. Plus there is a filter in there.

[John2189 503]

Ok i ran it today. I took the oil cap off and the back pressure almost blew it out of my hand. I checked the hose coming from pcv valve it was blowing air out of it too 

[Snoopy11 5,717]

24 minutes ago, John2189 said:

Ok i ran it today. I took the oil cap off and the back pressure almost blew it out of my hand. I checked the hose coming from pcv valve it was blowing air out of it too 

Gotta be crankcase vent issue...

 

Don

[John2189 503]

1 hour ago, Snoopy11 said:

Gotta be crankcase vent issue...

 

Don

Im still thinking it’s a head gasket. Ill start with the pcv valve. What I can tell by the repair manual, looks like a reed valve. I assume it should be closed. If its closed, I’ll pull the heads. 

[John2189 503]

Well I ran it to mow back yard before I tear it down. I checked the oil cap on the valve cover again and it has both pressure and vacuum.  The pressure I would compare to what comes out of the exhaust at idle. I checked it when cold start.  

[JoeM 7,923]

@John2189 Got to do a cylinder leak down test. You should get some pressure in the crankcase but not that much.

 

If you take off the valve covers during the test, while the cylinder is pressurized, you may now it is a head gasket. At the top of the head would be the place where the air would escape into the valve train area.

 

And it will confirm the condition of the rings. 

 

[John2189 503]

Joe, I will see if Oriellys has a leak down tester. 
If I took off the valve covers and  cranked it over with out starting it, would I be able to tell if it was leaking compression in the valve train by the push rods?

 

 Thanks for all your help 

[JoeM 7,923]

3 hours ago, John2189 said:

would I be able to tell if it was leaking compression in the valve train by the push rods

It would have to be leaking bad. 

 

Harbo Freight sell a cheap one (25$).....but then unless you are into it, might not ever get used again. Might just save you a lot of work.

 

 

[John2189 503]

13 minutes ago, JoeM said:

It would have to be leaking bad. 

 

Harbo Freight sell a cheap one (25$).....but then unless you are into it, might not ever get used again. Might just save you a lot of work.

 

 

I think Oreillys loan tools for free 

[Gregor 4,847]

The hardest thing about doing a leak down test, is somehow preventing the engine from moving while performing the test at TDC, or slightly after TDC on the power stroke. You have to get a hold of the crank somewhere and hold it. Not as simple as it sounds.

[John2189 503]

3 hours ago, Gregor said:

The hardest thing about doing a leak down test, is somehow preventing the engine from moving while performing the test at TDC, or slightly after TDC on the power stroke. You have to get a hold of the crank somewhere and hold it. Not as simple as it sounds.

I can energize the pto and hold it there 

[Gregor 4,847]

Might work.   Have never tried that.

[JoeM 7,923]

On this engine it is not hard to hold I've done a few and not had to hold them as of yet. If necessary the drive shaft is right there and easily secured with a pipe wrench. The best way of getting TDC is to remove spark plugs, air cleaner, and  the valve covers. Have the throttle open and remove the guards on the side of the drive shaft. Turn the drive shaft and watch the valve train as it comes up on compression, You can put a thin screwdriver into the spark plug hole and feel the piston moving up. You can rock the drive shaft and feel when the piston to put it right at TDC.

 

After finding TDC, I like to put a reference mark on the flywheel screen to the shroud with a paint marker. I put this mark at the area where I think the center of the coil is located beneath the shroud. This is handy if you put a timing light on to check ignition advance. Also, on twin cylinder machines, it will help locate the general area of TDC for the other cylinder.

 

When you get the leak down gauge set, you need to confirm if the two gauges are reading the same. Do this by putting air into the gauge not hooked up to the cylinder   and slowly turn it up to 80 psi. If the gauge set is good they will read within a few pounds. ie. 80/77.

 

When you do the test it needs to be quiet so you can listen to where the air is escaping. Carb, exhaust, or crank case and or a combination of both.

 

John I know you ask about being able to look at if the head gasket is blown internally. Here is a pic of the area, the offset is where the head gasket resides.

 

 

 

[John2189 503]

Joe, thanks for the info. I hope to get the mowing season done, then I’ll tear into it. It seams to run ok. I don’t think I’m doing any damage by running it. 
 

john