The Dreaded Kohler Knock-Rattle

This isn't the first time I've had to deal with knocking-rattling Kohler's. Most of the ones I have worked on have had WAY too much end play in the crankshaft, probably due to PO's thinking that the bearing plate shims were just gaskets so let's just use everything that came in the rebuild kit, WRONG! My 416-8 Magnum has knocked since the day it was brought home with 1808 hours on the meter and it now has 1841 hours and has moved and spread 22 tons of gravel and plowed the garden with a 12" Brinly turning plow, with never a hiccup. The easy way to tell if you have too much end play in the crank is to engage the PTO and see if the noise is reduced, if so the cure is to pull the bearing plate and re-shim but before you do, take a measurement of the crank lateral travel with a dial indicator to see how much movement you have, mine was .045 inches which is well beyond the factory setting of .003-.020.

The factory method requires removing the engine and oil pan and measuring the side clearance with a feeler gauge, which is not necessary if you have a dial indicator as shown below.. With the PTO engaged zero the dial indicator, then disengage the PTO and pull the PTO clutch outboard and check the dial to see how much lateral play the crank has. Repeat this procedure after re-shimming to verify the end play.



In this case I removed .035" of paper shims to get the clearance back to specs. Be sure to measure the shims with a micrometer and subtract the correct amount to achieve the desired end play. White shims are anywhere from .010 to .015, black shims are .030 but use a micrometer to be sure!



You can see that this engine has been torn down before because of the dinged up crankshaft end, probably for rings/piston/rod replacement.



Hope this helps someone out there fretting about their knocking Kohler. Oh! The bottom line is, this one doesn't knock any more!!

I went back and edited my original post to include the shim color thickness which I had left out. Be aware that non Kohler shims will vary so be sure to measure them.

Interesting and informative post, Major...thanks for taking the time to share the details and photos. Curious...the "knocking" is simply the PTO traveling on the crank essentially? I have never experienced this sort of thing, but would be curious as to what is actually happening. Does it actually sound similar to a low end motor concern...maybe like a rod knock? Thanks!

FewMoreMiles wrote: Interesting and informative post, Major...thanks for taking the time to share the details and photos. Curious...the "knocking" is simply the PTO traveling on the crank essentially? I have never experienced this sort of thing, but would be curious as to what is actually happening. Does it actually sound similar to a low end motor concern...maybe like a rod knock? Thanks!

Jeff, what causes the knock, which is sharp and hollow sounding, is excessive side play in the crankshaft causing it to move from side to side on the main bearings. When the PTO is engaged it forces the crankshaft to seat on the left side main bearing, eliminating or greatly reducing the knock.