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Kohler K321S Seized...

kohler k321s

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#1 frenchy OFFLINE  

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Posted April 22, 2012 - 06:50 PM

I managed to wreck my engine again. This time the connecting rod seized up. I want to know from the pros... should I re-work the connecting rod faces or just buy a new assembly? See pics of connecting rod and crankshaft.

The other thing that I believe may have contributed to the problem is when I was re-assembling from the last failure, the manual said to make sure the marks match on the connecting rod and cap. I couldn't find these marks, so basically looked at both and went by what I think is the casting hole marks. I think this cause an oil flow problem as there is an oil hole on that cap and it must need to be on one side or the other. Can anyone shed light onto that part?


Connecting Rod.jpg
Crankshaft.jpg

#2 Gtractor ONLINE  

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Posted April 22, 2012 - 07:11 PM

Thats a bummer! Did you Plastigage the clearances on the rod during assembly? Those tolerances are very critical - you have to know for sure - there is no guessing there. Any time I ever rebuilt a K series Kohler I had the machine shop bore the rod out for an insert and that makes a very good engine pretty much bulletproof. I imagine that rod could be saved by going with a bearing insert, otherwise it is scrap. The oil hole has to be on the front side of the cap - in the direction of rotation so oil is forced into the hole.

Edited by Gtractor, April 22, 2012 - 07:12 PM.

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#3 chris m OFFLINE  

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Posted April 22, 2012 - 07:26 PM

I agree with Gtractor. Either bring the rod and crank to a machine shop, or else you'll have to find another crank and rod, either new or used. Good luck, and I am sorry this happened to your engine. I've had this happen so I know your pain.
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#4 frenchy OFFLINE  

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Posted April 22, 2012 - 10:12 PM

So I can't just replace the rod and use the existing crank? That's gonna suck... not sure where i'll be able to find both... thanks for the help guys!

#5 olcowhand ONLINE  

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Posted April 22, 2012 - 10:16 PM

I use muriatic acid to eat the aluminum off the crank, then I dress the crank journal with fine emery cloth. Then I check for out of round or undersize wear with a micrometer. Most times the crank ends up ok to use for me. Not always the case of course.
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#6 frenchy OFFLINE  

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Posted April 22, 2012 - 10:24 PM

I shut her down the second it seemed to be running weird, hopefully I minimized the damage.

#7 chris m OFFLINE  

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Posted April 22, 2012 - 10:33 PM

Do Like Daniel (olcowhand)said. He is right you might find that the wear on the crank is just the aluminum that was picked up from the connecting rod. It's worth a shot. Good luck.

#8 frenchy OFFLINE  

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Posted April 23, 2012 - 08:50 AM

Sounds good. Thanks again all for the help. I'll post results once i've completed the rebuild.

#9 frenchy OFFLINE  

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Posted April 23, 2012 - 10:26 AM

Sourced the connecting rod, $73.00. Glad I was able to find a dealer that was very knowledgeable. The guy said "Make sure you put that cap on in the direction of the crank." Awesome... I told him "Yeah, pretty sure that's why this seized up on me..."

The first guy from another dealer I talked to didn't want to help until I asked if there was another Kohler dealer in town. Brutal.

#10 frenchy OFFLINE  

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Posted April 23, 2012 - 12:30 PM

I use muriatic acid to eat the aluminum off the crank, then I dress the crank journal with fine emery cloth. Then I check for out of round or undersize wear with a micrometer. Most times the crank ends up ok to use for me. Not always the case of course.


Hi "olcowhand", so do I just soak the crank in the acid or do i apply it with a brush and scrub the surface? I've neve done this before...

#11 olcowhand ONLINE  

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Posted April 23, 2012 - 04:55 PM

Hi "olcowhand", so do I just soak the crank in the acid or do i apply it with a brush and scrub the surface? I've neve done this before...


Many times I do it while still in the block. Brush it on full strength, IN OPEN AIR, as it produces a nasty fume which is not good for you at all! Just a wet brushing, not dripping off. Soon as it stops foaming, rinse with water, then do again till all the aluminum is gone. It doesn't attack ferrous metal, so the crank & block are safe. It loves to eat aluminum, brass,....any non-ferrous metal. The crank journal may still look discolored after the aluminum is gone, but will shine like new when buffed with a strip of fine emery cloth.
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#12 frenchy OFFLINE  

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Posted April 24, 2012 - 08:22 AM

Thanks much! Will be working on that tonight! I might try to take a video of it too just for kicks. Maybe I can sucker my wife into filming it instead of me trying to do both things at once!

#13 broken2 OFFLINE  

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Posted April 24, 2012 - 05:47 PM

Hope you can video it, will be interesting to watch.

#14 Kyocum OFFLINE  

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Posted April 24, 2012 - 06:56 PM

On a K series Kohler the the cap has to be correctly installed with whatever marks there are aligned. When installing the rod on the crank it is always good practise to use a piece of plastigage as already mentioned. The last thing is always make sure the oil hole in the rod cap is facing the camshaft side of the engine. Very critical

#15 frenchy OFFLINE  

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Posted April 25, 2012 - 08:31 AM

Hi All

Well i tried to video the process, but really you can't see much. I'll admit, I expected visible fumes and some crazy chemical reaction, but it was more like putting peroxyde on a wound... little bubbling.

After removing the aluminum, I dressed the crank surface with emery cloth and put everything back together with the new rod. I want to add here that the new rod not only has arrows for indicator marks, but also a blue piece of paper in the box that says "ensure that oil hole on connecting rod cap is facing camshaft." Thank you Kohler!

Prior to rebuilding, I dry fitted the rod to the crank with plastigauge and it was reading a tolerance of .003. Pretty sure that's acceptable by Kohler standards.

Thanks again to all for your great assitance. This community is very knowledgeable and friendly!

Edited by frenchy, April 25, 2012 - 08:32 AM.





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