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Questions About Kohler K341 Rebuild


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#1 dthomp17 OFFLINE  

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Posted July 19, 2014 - 06:31 PM

My kohler k341 from my cub 1650 has been burning some oil, especially on startup, and I need some experienced opinions.  The motor runs fine and seems to have adequate power but it smokes,.  I pulled the head to check it out and found that the exhaust valve had what I thought was excessive side to side play when fully opened. I assumed that either the valve guide or valve stem (or both) was worn resulting in this side to side play.

 

I took both valves out and measured the stems with a digital caliper with a rated accuracy of + 0.001".  Both valves were within spec.  However, the exhaust valve looked like the stem diameter was smaller about 3/4" below the valve face.  This was in a non-mechanical wear area and I was surprised to see it.  Anyway, I measured that suspected area and sure enough the measurement was about 0.017" smaller than the rest of the stem. 

 

I had no way of measuring the ID of the valve guides but I knew that the OD of the intake valve was larger than the OD of the exhaust and measured about 0.310 - 0.311".  Since the Kohler manual calls for reaming newly installed valve guides with a 0.3125" reamer, I assumed the guides would be at least 0.3125" ID or larger.  I tried inserting the intake valve stem into the exhaust valve guide.  If it fit, I would know that the ID of the exhaust guide was at least as large as the OD of the intake valve stem and if it still had significant side to side play, the guide would probably need to be replaced.  The intake valve stem wouldn't go into the exhaust guide so the ID of the exhaust guide is less than 0.311".  It also means that the ID of the exhaust guide is less than the diameter of the reamer that Kohler recommends using for new guides which surprised me.

 

The cylinder bore looked really good and measured within standard spec for diameter and also for "out of round" and "taper".  I didn't see any evidence of damage to the cylinder walls.  The crankshaft measured right at the maximum wear limit but with the accuracy of my digital calipers it could be out of spec by up to 0.002" or within spec 0.001" above the maximum wear limit.  I think the crank is OK because the connecting rod to crank clearance measured 0.002" with plastigage.  This is within the maximum wear limit listed by Kohler.  The connecting rod also looked good and the bearing surface showed no evidence of overheating or scoring.  The piston also measured within standard spec with only a slight amount of scoring, about 1" wide, noted in an area above the top ring.  I measured the piston ring end gap for the old rings and I think I now know why it was burning oil.  The top ring end gap was 0.033", the second ring end gap was 0.072", and the oil ring gap was 0.173".  Maximum wear piston ring end gap from the Kohler specs is 0.030".   In addition, the ring gaps weren't staggered 180 degrees as recommended.

 

There were no balance gears and I don't know whether or not this engine ever had them.

The engine looks like it's been opened before as there was some RTV silicone gasket sealer on the oil pan gasket.  Don't know what if anything was done when the engine was opened.

 

Based on what I found, I'm thinking I will simply do a light cylinder honing, replace  piston rings with standard size (possibly new standard piston too), and new valves.  Any thoughts or suggestions would be appreciated.

 

 

 

 


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#2 propane1 ONLINE  

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Posted July 19, 2014 - 06:47 PM

I just did a 341 a few months ago.  I would put the new piston in.  Chrome rings, people say are better.  I had a 301 split the piston at the oil ring a few weeks ago, thats why I  say the new piston.  While its apart.  Just my opinion,  Noel

 

Some kits have every thing you need to rebuild. Valves, gaskets, piston, rings, rod, seals and so on.   


Edited by propane1, July 19, 2014 - 06:50 PM.

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#3 olcowhand ONLINE  

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Posted July 19, 2014 - 06:58 PM

As far as the balance gears, if the bosses inside don't have the stubs pressed in for the gears, then it came factory without balance gears.  If the stub pins are there, then someone took the gears out.


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#4 dthomp17 OFFLINE  

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Posted July 19, 2014 - 07:12 PM

There are no stub pins there so it apparently came that way from the factory.


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#5 dthomp17 OFFLINE  

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Posted July 19, 2014 - 07:14 PM

I just did a 341 a few months ago.  I would put the new piston in.  Chrome rings, people say are better.  I had a 301 split the piston at the oil ring a few weeks ago, thats why I  say the new piston.  While its apart.  Just my opinion,  Noel

 

Some kits have every thing you need to rebuild. Valves, gaskets, piston, rings, rod, seals and so on.   

I'm thinking more and more about going with the complete kit too.


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#6 JDBrian OFFLINE  

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Posted July 19, 2014 - 07:30 PM

Complete kits are reasonably priced on Ebay.  A quick look at the parts diagrams for a 1650 should tell you if the gears were installed in the stock engine. Some manufacturers did not use the gears when using rubber mounted engines like JD did with the 314 and 316K. 


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#7 propane1 ONLINE  

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Posted July 19, 2014 - 07:58 PM

I took the balance gears out. Seems most people say to take them out. I used the LGT 165 for grass cutting last weekend and it work great. I am not sure , but I don't see any difference, may be smoother. When I was rebuilding it, I asked a question on here as to take them out or leave them in was, the answer was , Their purpose was to make a good block useless. Noel

And the last two I took apart , a 14 and a 12, with the last tow months or so did not have any balance gears in there. Had the stubs.

Edited by propane1, July 19, 2014 - 08:05 PM.

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#8 dthomp17 OFFLINE  

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Posted July 19, 2014 - 08:12 PM

I took the balance gears out. Seems most people say to take them out. I used the LGT 165 for grass cutting last weekend and it work great. I am not sure , but I don't see any difference, may be smoother. When I was rebuilding it, I asked a question on here as to take them out or leave them in was, the answer was , Their purpose was to make a good block useless. Noel

And the last two I took apart , a 14 and a 12, with the last tow months or so did not have any balance gears in there. Had the stubs.

Most people that I've read about took them out also during rebuild.  I had planned to take them out if I could do it without major problems.  Glad to see that they weren't there when I opened it up.


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#9 boyscout862 OFFLINE  

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Posted July 20, 2014 - 05:02 AM

While you have it apart, you can do the entire job and then not have to do anything but regular maintenance on that engine for the rest of your life. I'm doing a 12hp now. And have bought several WH GTs just to get the engines off them to rebuild for use on my other GTs. Good Luck, Rick

 

BTW I find that Marvel Mystery Oil added to the gas helps to clean and lubricate the inside of the engine. I've been using it for 46 years and it has helped all of my auto and tractor engines.


Edited by boyscout862, July 20, 2014 - 05:05 AM.

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#10 Trav1s OFFLINE  

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Posted July 20, 2014 - 08:02 AM

Worth looking into if you have it apart:

 

http://www.kirkengin...KohlerPartI.pdf

 

http://www.kirkengin...ohlerPartII.pdf

 

This formula works on all K series engines.  

 

I am going with this piece when I rebuild the K301 in my JD 312:

http://www.kirkengin...BalancePlateKit


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#11 dthomp17 OFFLINE  

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Posted July 20, 2014 - 08:42 PM

Worth looking into if you have it apart:

 

http://www.kirkengin...KohlerPartI.pdf

 

http://www.kirkengin...ohlerPartII.pdf

 

This formula works on all K series engines.  

 

I am going with this piece when I rebuild the K301 in my JD 312:

http://www.kirkengin...BalancePlateKit

Wow that's an impressive amount of time and work to upgrade a Kohler K series engine.  I'm afraid I don't have the time, money, patience, or ability to do all that to the engine.  I'll be happy if the rebuild results in an engine that runs good, doesn't burn oil, and last awhile.



#12 toomanytoys84 OFFLINE  

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Posted July 27, 2014 - 12:49 PM

Do it all. You will regret it later if you dont.

We lost our 12 hp Kohler in our 128. I haven't tore into yet but it was experiencing the same symptoms as yours plus it was smoking under heavy load after a while.

#13 dthomp17 OFFLINE  

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Posted July 27, 2014 - 01:29 PM

Do it all. You will regret it later if you dont.

We lost our 12 hp Kohler in our 128. I haven't tore into yet but it was experiencing the same symptoms as yours plus it was smoking under heavy load after a while.

What really surprised me when I opened up the k341 was how badly the rings had worn while everything else was in decent shape.  At first I thought I would just replace the minimum, but after thinking more about it I decided to do it all.  When you start adding up individual parts it doesn't take long to be near the cost of a complete rebuild kit.  I ordered a master rebuild kit which includes a new piston, piston rings, connecting rod, valves, crank seals, gaskets and I believe everything I need for a complete rebuild.  I did decide to go with the after market kit which included everything for $119 plus shipping.  I believe that OEM Kohler parts would have been more than twice that amount.  I know some say use only OEM Kohler parts and others say the after market parts are fine.  I'll let you know when I get it put back together how it works.  I'll mainly be using it for cutting grass, moving my utility trailer around, and some light garden plowing.


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#14 olcowhand ONLINE  

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Posted July 27, 2014 - 01:32 PM

I had issues with the aftermarket valves a couple times, but the rest held up fine for several engines.


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#15 dthomp17 OFFLINE  

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Posted July 27, 2014 - 02:21 PM

I had issues with the aftermarket valves a couple times, but the rest held up fine for several engines.

What kind of issues did you have so I'll know what to look for?






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