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airgunner

Kohler Command CH18 Leaking Valve Covers

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airgunner

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.

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PhanDad

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):

IMG_8351.thumb.JPG.b94b07ed9d1e7772fed996734e68c11e.JPG

A close up of the new cover:

IMG_8352.thumb.JPG.afe2f461880e609878831332688d3ca5.JPG

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

5cb63df2694ba_CH18ValveCoverKit24755140_Cover.thumb.JPG.f053844a97051da2f64f6349b3742a22.JPG

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

 

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Bill725

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.

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PhanDad
46 minutes ago, Bill725 said:

Hoping he will post a picture.

Kevin's 75th had aluminium valve covers:

kevin75th1.jpg.cd9eba60749dbf78e1a74ce9f7f97878.jpg

Maybe by one of the suppliers you list.  

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

jn_75th_anniv.jpg.98fdd0d9d9ffc6a824a973a8a7017450.jpg

 

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ShaunE

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.

https://www.zkbrmachine.com/product-detail/oem-replacement-billet-valve-cover-457

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acken

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?

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ShaunE

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.

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