Kohler Piston

[MalMac 1,332]

I had to tear down one of my M14 mags. Looks like I am going to have to put a new piston in it along with a rod. The piston that came out of it is the Mahle style. Now I have always used OEM but this time around I am using aftermarket because I just can not swallow the price for OEM. Especially for a Mahle piston. Now in my search for a Mahle style in aftermarket I can not find one. I don't see any reason why I can not switch back to old style, but I just wanted to ask in case any of you gurus on here know where a aftermarket Mahle style can be found or why I can't switch back to old style.

[Fordiesel69 270]

Are you going to the next size over?

 

If you are, PLEASE use the mahle, it runs much cooler, will allow the bore to last longer, the alloy is of better material which reduced scuffing, has better oil control, and is quieter.  You cannot find these aftermarket, and will have to pay the pretty penny. 

 

If you must go the cheap route you will need to find a style A piston typically used on K series, and a wide rod to go with it.  These are just about everywhere. Yes you can do this with no ill effects, its just the mahle and narrow rod is much better quality. 

 

You should not use a narrow rod designed for the mahle pistons, with a style A piston, even though it will fit and work.  The engine will be a tad out of balance.

[MalMac 1,332]

I understand what your saying. I have always used OEM but this time around just way too much money. I know everything has gone up but Kohler is insane. This is not a racing motor or one of my farm tractors making money.

[Fordiesel69 270]

Then a style A piston, and a wide rod.  I have had great luck with the kits on ebay, just obtain them before getting the machine work done.

[MalMac 1,332]

By just looking at the bore without taking any measurements. Looks like it might just need a good hone job. Was taking a closer look at the Piston and cleaned it up good. There are only very light scoring marks at the top of the piston above the first ring. I have never put any piston back in with that but these are ever so slight I wondering if just honing the bore and new rings if I can get away with using the old piston. When I got this motor it was supposed to be a bolt on go, plug and play situation. Putting money into this one was not on the schedule. So that's why I am not really willing to put big amounts of money into it.

[Fordiesel69 270]

If it is currently a style D and it is still failrly tight, then do just rings.  If style A already, replace.

[Molon_Labe 731]

I'd go ahead and invest in the ebay kit since it's already torn down. $120 invested in a kit is pretty cheap insurance and peace of mind.

[MalMac 1,332]

Since it's a Mahle that came out of it, that's the only reason I am even considering re-using it. Guess it all depends on what the measurements say. The measurements will be the ruling factor here. All of this is just a shame, because this engine was bought from a trusted individual. Bought under the pretense of super low hour, no problems. Just sour grapes I suppose and in the end its a "Buyer Beware World." I have no one to blame but myself.

[Catmanii 36]

About 12 years ago I bought my C-175 in Oklahoma. It had the KT-17 engine in it and yes it had thrown a rod so I go it very cheap. Then I found out what the parts cost to fix it. WOW I found another KT-17 in the Dallas area with the same problem and bought it for $50 bucks. It was from a John Deere and had a 1" crank. I mixed the two engines togather and came out with 1 running engine. Had to use the John Deere 1" crank due to damage on the WH crank so had to use a sleve to make it work. Point being that was 12 years ago and the darn thing it still running and I bought nothing new except a gasket set.. My place is flat so oiling is not a problem for the KT-17. It is really nice to have new evertthing, but just not always necessary. I would hone and use the old piston and rod. 

[Catmanii 36]

I forgot, not only still running, still not using a drop of oil between changes. 

[pacer 3,176]

When I was young (MANY years ago!!) and had no money and drove some real clunkers I would put rings only in some really fonky looking bores and more times than not I would luck out and they would seat, or at least cut oil consumption/smoking quite a bit. Mic that cyl out and if only slight wear, throw some rings at it, should be less than a $100 so it anit gonna hurt the pocket book much.

[MalMac 1,332]

I am not sure what I am going to do with it. Right now it's going on a back burner. Like I said the motor was bought with the intension of more or less a bolt on and go. I have rebuilt several before and never cut corners believing in when you do that your just shooting yourself in the foot. Since this motor was bought with the idea in mind of not racking up money in it, it may just sit for a while. Having trouble convincing myself to just throw rings in it and not rebuild it OEM or aftermarket. After the last one I rebuilt I told myself no more OEM, prices are just getting too far out of line. Don't need the tractor to last another 20 yrs. Won't be able to get on and off of them by then. Lol

[Molon_Labe 731]

I am not sure what I am going to do with it. Right now it's going on a back burner. Like I said the motor was bought with the intension of more or less a bolt on and go. I have rebuilt several before and never cut corners believing in when you do that your just shooting yourself in the foot. Since this motor was bought with the idea in mind of not racking up money in it, it may just sit for a while. Having trouble convincing myself to just throw rings in it and not rebuild it OEM or aftermarket. After the last one I rebuilt I told myself no more OEM, prices are just getting too far out of line. Don't need the tractor to last another 20 yrs. Won't be able to get on and off of them by then. Lol

 

Mac I'm with you on OEM pricing, where is the justification? Aftermarket has worked well for me on many rebuilds for a fraction of the cost. I figure if they made it for 35+ years before the first rebuild they will surely out last me.

[Pullstart 65,471]

If this came from a trusted individual, what about letting them know what you found, maybe they would be willing to make it right and help out with the cost of repairs?

[km3h 543]

You never said why you are having trouble with the engine. What was wrong with it that made you tear it down. Was it burning oil? Making noises? Were the rings stuck to the piston?

If the bore is smooth and not scored I would hone it and put a new set of rings in it. Don't worry about dings in the side of the piston. If the rings can seal properly the dings won't make any difference.

If there is what looks like a burn line leading to the exhaust valve then the engine was probably running lean. That's probably a carburetor problem.

[MalMac 1,332]

When I started the engine up It was nice and smooth running but starting to burn oil. So not really knowing a lot about the motor I decided that I would check it for carbon build up. Pulled the head and found excess amount of oil on top of the piston. Upon further inspection I believe that the engine had a stuck ring and had been run hot at one time or another. So I decided to go ahead and tear it down for a closer inspection. What I did find was the very early beginnings of trying to score the cylinder wall and the very top of the side of the piston. So that's as far as I have gone with it. Probably won't do anything with it till winter or early next spring. I might take it in to my engine shop and let them do some measurements for me. I use to have all the measuring tools to do all that but some low life stoled them from me.

[km3h 543]

Well if the cylinder is scored below the top ring that could be an issue. If a ring was stuck, that could cause the walls to develop an oval shape and would need a re-bore. I would take it to the shop and have them mike everything. Sounds like you are on the right track.

[Warning:Unsupervised 82]

 One can get lucky

running an engine hard at high RPM raising the compression up enough to seat a sticky ring. Nissan had some recalls on 4cly engines yrs ago and Nissan mechanics (ones my nephew) first took the car out on a "hard drive" then had the customer drive it normally for awhile and test for oil burning again. Many owners never had ring issues return, some got a new engine. 

 

   I was going over my M14 last week having starting issues and heard a slight knock. Knowing about the Kohler knock I adjusted the junk  Walbro carb "once again" and the knock went away.

 Still had starting issues no matter what so I finally gave up on my junk Walbro and ordered a new #30 Carter/Kohler carb and what a difference it made.

 My 414-8 tractor starts/runs much better with a #30 but my lazer temp gauge shows it runs about 91 degrees cooler as the Walbro simply ran too lean. Just rebuilt my Walbro last fall, they're just junk.

 

 I wanted to mention the Kohler knock since it can be a bit loud if fuel is bad or a carb is out of wack so hearing it can be a bit scary & can even trick some into engine rebuilds I bet?

 

  Fwiw:  Got my carb at Kustom lawn & garden and Clark Racing.

 aka- Cfamily10 on ebay because their carbs are SAE threaded so the oem Kohler kits fit.

Thanks all!

 

Edited July 5, 2020 by 123GO