Jump to content

Unofficial Home of Old Simplicity & Allis-Chalmers Garden Tractors


Kohler Command CH18 Leaking Valve Covers

Recommended Posts


Question for the experts here...working on my late model Sovereign project tractor, almost done and ready to mow. I ran it around the yard today, and noticed a most unusual problem. Both cylinder valve covers are weeping oil-from the top surface. The bottom gasketed side is fine. I can wipe the oil droplets off with my finger as it runs, and the drops reappear in the exact same spots. It is as if the plastic or composite valve cover itself has microscopic pin holes or porosity in it. I have never seen this before, a quick Google search didn't really turn up much. I'm guessing I will need new valve covers on both sides, just wondering if anyone has seen this before.

Share this post

Link to post
Share on other sites

CH18 valve covers were changed one or two times from the originals, but I thought mainly for the seal (kind of a flat O-ring).  But corners where the bolts attach are also different.  A side-by-side pic (left cover with fuel pump from a 2001 CH20; right cover part # 24 755 141-S purchased 2014):


A close up of the new cover:


New bolts came with the valve cover; here's the directions:


Maybe the original bolting caused stress cracking of the cover that leads to the leak you described.


  • Like 1
  • Thanks 1

Share this post

Link to post
Share on other sites

FYI, Midwest Super Cub and Zach Kerber Machine and Design both manufacturer cast aluminum valve covers. ShaunE just purchased a set of Zach Kerber's. Hoping he will post a picture.

Share this post

Link to post
Share on other sites
46 minutes ago, Bill725 said:

Hoping he will post a picture.

Kevin's 75th had aluminium valve covers:


Maybe by one of the suppliers you list.  

The prototype 75th also had chrome or aluminium valves covers, different from above:



Share this post

Link to post
Share on other sites

I just bought these.  Very nice pieces.  I do NOT like the stock covers.  I have owned all three styles.  The only way I have ever found to stop the covers from leaking is to use sealer.  The SAME as the Triad covers.


  • Like 1

Share this post

Link to post
Share on other sites

I know from Triad discussions it is suggested to replace overhead fuel pump with vacuum type.  What about CH27's, same theory to reduce chance of valve cover leakage?

Share this post

Link to post
Share on other sites

In my opinion, yes if the impulse pump will supply enough fuel to the higher hp engine.  I have no experience with the CH27.  However the new Kohler engines that are 18-20 hp that individuals are using to re-power Sovereign platform tractors need to have that cover replaced & an impulse or electric fuel pump installed for hood clearance.  That is why I purchased these aluminum covers.  They also make taller covers if one was going to install Roller Rockers.

Share this post

Link to post
Share on other sites

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now

  • Who's Online (See full list)

    • Mine19821
    • 720nut
    • Wilbur643
    • SmilinSam
    • gwiseman
    • rbstuartjr
    • Bill725
  • Today's Birthdays

    1. littlefan
      (60 years old)
  • Recent Status Updates

    • Paul M.Murphy

      Paul M.Murphy

      Hello glad I got on this site. I hope to upload a couple of photos of my Simplicity Broadmoor 
      Model 707 Tractor. I have replaced all the belts on it and installed a new ignition switch.
      Have a mower deck which was in poor shape , repaced a couple of bushings and welded the
      deck where there was some holes. The tractor and mower deck came from a friend and the 
      mower deck metal was getting pretty thin. Some new metal was put in it and we also undercoated the underside of the deck. This was done by my friend Greg Toulman.
      I have not put the mower deck on the tractor yet, waiting for Greg to come home and give me a hand. Can you please tell me if there is a manual for the mower deck and where I could get one.
      I would also like to get some moon wheel discs as well.
      I will try and down load some photos of the tractor when my wife shows me how to. 
      I really love driving this tractor and also how well it is made compare today's tractors, especially the flexible rear end and the rollers.
      Tell the next time 
      · 9 replies
    • jbrooks

      jbrooks  »  Talntedmrgreen

      folowing  this from a link at the downloads.  I just rescued an AC 920 with the lambodini diesel. I can' t download  yet .  Where did you find the PDF copy you posted. . I would like to figure out how to adjust the injection pump. 
      I assume it's a bosche, correct
      · 0 replies
  • Adverts