Wheel Horse Kohler K341 Knocking - 1300 hours

[Al C. 1,405]

The Kohler K341 engine (1982, 16hp) on my Wheel Horse SK-486 is knocking.  The engine has 1300 hours, does not smoke, has great power, and starts on the first crank.  It has made the knocking sound for as long as I have owned it (one year).  I have cleaned the cylinder head, replaced the head gasket, cleaned the fins, put in a new spark plug, replaced the points (0.018 gap) and condenser, changed the oil, replaced the air cleaner, and tuned the hi/low carburetor mixture at 1200 and max RPM.  The sound has not changed.  The knocking disappears completely when I engage the PTO.  In fact, even slight pressure on the PTO will cause the sound to stop.  I am not an engine expert, but I am concerned that there is "play" somewhere in the engine that is not good.  So, before something really bad happens  I am interested in opinions whether this is normal or whether I need to have the engine looked at.  I read about a lot of engines being rebuilt.  Does this indicate a rebuild is in order?  If so, is this something I can undertake myself with a "rebuild kit"?  Otherwise the tractor is like new and I want to keep it that way.  Appreciate everyone's input.  (Video link and picture attached.)

 

https://www.dropbox.com/s/utp94ukos6oe97z/File Jul 26%2C 2 51 38 PM.mov?dl=0

[N3PUY 1,031]

Sounds like the main bearings on the crank.   Too much play side to side.  Take off the PTO pulleys and measure the end play of the crankshaft.   It is adjustable with the paper shims on the flywheel side.  When you engage the PTO it pushes the crank to the flywheel side.  

  Tractor looks too nice to be that noisy.

Edited July 26, 2016 by N3PUY

[rmaynard 14,897]

 is exactly what I was thinking   The more shims that are placed between the bearing plate and the crankcase, the more end play. 

[Al C. 1,405]

I'll give it a try tomorrow.  Just curious, the adjustment you are referring to, can I do this myself?  Does the engine need to be removed from the chassis?  

[N3PUY 1,031]

You can probably do it yourself.   It can be done on the tractor.   I think in a Kohler engine manual there is the spec for the end play.  

[WHX?? 46,774]

No engine should not have to leave the frame. You will need to remove some tins and pull the flywheel. Before you do this do check the end play like the guys suggested and while you have the pto off check the bearings in it as well. Should have the end play specs in the manual here.

its a nice looking tractor

[Al C. 1,405]

So here is the final chapter of the story.  I'll title it, "Amateur Falls on Sword".  I took the pto pulley off and prepared to remove the flywheel.  Then I tested for the end play on the crank shaft.  There isn't any!!   I tried everything I could to move the shaft.  Hit it with a rubber mallet, pryed it with a crow bar - nothing.  After all that, I was concerned I might have damaged something, so I started it up.   Turned over on the first crank as usual, but there was no knocking. Convinced that I had done something that inadvertently fixed the problem, I put things back together.  Started it up - knock is back.   You guessed it, there is rythmic vibration in the mechanism that operates the PTO.  I could shoot myself.  All this effort, and the source is the simplest thing.  So, I want to apologize for consuming your guys' time.  But also want to thank you for teaching a newbie another aspect of the infamous Kohler engine.  

Edited July 29, 2016 by Al C.
Typo

[rmaynard 14,897]

Glad you found the problem, and thanks for letting us know. 

[953 nut 51,682]

3 hours ago, Al C. said:

apologize for consuming your guys' time.

No apology needed, we all learn from each other and that is the beauty of this site.   

[tunahead72 2,341]

6 hours ago, Al C. said:

... You guessed it, there is rythmic vibration in the mechanism that operates the PTO...

 

I'm still learning, and don't really understand what you mean here, can you be more specific?  Thanks!

 

[Al C. 1,405]

What I thought was a knocking sound in the engine, turned out to be a vibration/rattle in the mechanism/clutch that engages the PTO for the mower deck.  

[Wheel-N-It 2,967]

Al, I owe you dinner. I have the same situation with the K-341 in my 416-8. The engine starts right up hot or cold, never smokes, has lots of power, and actually seems very well balanced and smooth for a big 16 single. There is 870 hours showing on the working hour meter. Like you, I too learned over time there was nothing wrong with the engine, the root cause of the noise is in the PTO assembly. Thank you for this thread. I'm sure it has put the mind of others here at ease. I'll be the first to admit the noise can be of great concern.

[tunahead72 2,341]

I agree with Van, this turned out to be a very useful thread.

 

I have a K241 with a similar noise, it basically runs well but the noise has worried me for a while now.  I'll be checking out the PTO assembly soon to see if that's the problem.  Do you see anything in particular that can be done to reduce or eliminate that noise?

 

Also, and I'm no expert on engines, but I recently saw a video on youtube (donyboy73 I believe) where a similar knocking was fixed on a Briggs and Stratton engine just by properly torquing down the engine mounting bolts.  I suspect our Kohlers are mounted more securely than his engine was, but I suppose any of them could come loose over time, it's probably worth checking as well.

 

And Al, I just read this entire thread a couple of times...  Your initial description of the problem and what you had done to investigate and correct it was really excellent.  Thanks for letting us all in!

[Wheel-N-It 2,967]

3 hours ago, tunahead72 said:

I agree with Van, this turned out to be a very useful thread.

 

I have a K241 with a similar noise, it basically runs well but the noise has worried me for a while now.  I'll be checking out the PTO assembly soon to see if that's the problem.  Do you see anything in particular that can be done to reduce or eliminate that noise?

 

Also, and I'm no expert on engines, but I recently saw a video on youtube (donyboy73 I believe) where a similar knocking was fixed on a Briggs and Stratton engine just by properly torquing down the engine mounting bolts.  I suspect our Kohlers are mounted more securely than his engine was, but I suppose any of them could come loose over time, it's probably worth checking as well.

 

And Al, I just read this entire thread a couple of times...  Your initial description of the problem and what you had done to investigate and correct it was really excellent.  Thanks for letting us all in!

Tuna, I think the noise is coming from the small outboard bearing in the PTO. This thread really has my curiosity up now and I may replace the existing PTO with another I have in the Wheel Horse barn just to see if that eliminates the noise.

Also I completely agree with Tuna's last paragraph. The way Al wrote his initial post in this thread was excellent ! It's written in a way that encourages others to chime in and help.

[kudzu3 323]

Great thread, now we know what to check first.

[Al C. 1,405]

I have not taken time yet to see if there is anything I can do to reduce the noisey PTO.  Candidly, I'm soooo happy that it is not the engine that I've started to disregard the sound.  I have to repeat what I've said a number of times.  This forum is a great place!!!   Everyone is so practical and willing to help out.  It is rare to find a bunch of "practitioners" who demonstrate such effective problem solving skills, good humor, and no ego or motive other than just helping each other out.  I have to imagine that there is something about the Wheel Horse product/brand, that attracts a bunch of us with these characteristics.  Along with the technology of this multi-media site, this is just a great place to listen, learn, and tune our toys.