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Kohler 321 oily mess-Source of oil leak?


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#31 JDBrian OFFLINE  

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Posted May 19, 2011 - 05:20 AM

Thanks for the input Daniel. It makes some sense that the 16HP would be the worst at galling the cylinder. Same block but larger bore which leaves less material and there is more force and heat due to higher HP. I wonder how much longer these engines would last if the cooling fins were kept clean. The design of the covers makes it hard to remove them all and properly clean the fins.
I want to measure the bore before I do any reassembly, just to see the extent of the wear. It looks to me like the head gasket was leaking on the block side. The pattern that is in the head gasket is imprinted into the block. The little indentations in the head gasket have become bumps in the block. This is not on the sealing surface but further out. It may be hard carbon, I'm not sure, but it is raised up a bit above the sealing surface. I figure I should try to smooth this down in order to give the gasket the best chance of sealing. After I get everything ready for assembly, I'll check the gap between the head and block before I proceed.
It dosen't look like there is a lot of erosion of the cylinder wall. It is hard to feel any ridge there now that I have removed the carbon. I am hoping there won't be too much blowby. I am going to try to come up with an oil separater to capture any oil coming out of the vent. The PCV breather will be rebuiilt so that it won't be an issue.
I don't have the time right now to get into a major rebuild. I hope to get a couple years out of this engine and then it will make a good project to rebuild it when I am retired in a couple of years. About repowering - Is it common for a modern engine to have output at both ends of the crank? If not, you would loose the PTO output. I have seen the Vanguard twins put into 140's so I assume they would be a valid choice. I would prefer Diesel but the choices seem rather limited. Perhaps a small marine diesel might work. I'll have to keep my eye out for something locally.

#32 KennyP ONLINE  

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Posted May 19, 2011 - 06:00 AM

Brian, looking a the pics, your engine look to be in better shape than my K341 was. I cleaned the carbon out, flattened the head as described above, honed the cylinder (after checking for wear/out of round) and installed new rings. Did wonders for it. Hope yours turns out as simple as that. This was my 2nd time of being inside a Kohler, so I asked a lot of questions. The first time, I had no help. But it still runs sweet.

#33 JDBrian OFFLINE  

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Posted May 19, 2011 - 08:30 AM

I have very little experience with engine work. I'll get the tools to measure the cylinder and see how bad it is. It actually was running OK before I took it apart. It was putting some oil out the PCV breather and seemed to be down a bit on power but it wasn't smoking. After seeing the mess of the head gasket I'm surprised it was running that well. What a mess that oil made of the engine. It has taken hours to get most of the goo off it.

#34 JDBrian OFFLINE  

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Posted May 21, 2011 - 11:49 AM

Tried to find a set of telescopic bore gauges yesterday and the only ones I could find were Starrett and over 100$. I tried to measure the bore with inside callipers and a micrometer but it is clumsy and probably not that accurate. However it looks like there is not a lot of difference between the bore at the spot where the carbon was built up and perpendicular to that. All my measurements were repeatable (reasonably good precision) and were within .001 of each other. The absolute value was about 3.500 but I don't trust the accuracy. I'll have to try again to find the gauges or borrow some from a mechanic friend of mine.
The head of the engine and the block both had a lot of hard carbon buildup where the gasket had been leaking. I got it off of the block very carefully. There was a noticeable ridge of it and I figured it had to be removed so the gasket could contact the block directly.
I am using 600 grit wet paper on a piece of thick glass to try to level the head. It appears that the carbon on the head is a low spot, as it is the last area to make contact. So far I have the milling marks removed from most of the head surface and hopefully I can get this flattened without removing too much material from the head.
How flat does this have to be? I figure it should be as flat as possible but is there much tolerance? This spot is right by the exhaust valve so it is probably the hottest area.

#35 olcowhand ONLINE  

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Posted May 21, 2011 - 02:21 PM

Harbor Freight has telescopic bore gauges. Not quality of Starette, but do just fine.

#36 JDBrian OFFLINE  

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Posted May 21, 2011 - 04:01 PM

I had made the rounds of my local sources for such things and no one had any or had none in stock. I went on the web site for Busy Bee Tools and found they had one listed. Called the store and asked if they had one in stock and they do. I had been in there last week and the kid at the counter said the only thing they had was an inside calliper.:mad2:
I'll have to wait until Tuesday at least because I don't think I'll be back in town until then.

#37 Billygoat OFFLINE  

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Posted May 22, 2011 - 10:11 AM

I learned something yesterday. I was in the store to buy 400 grit to do the head on my K321. An old friend (73) asked me what I was doing and I told him. He said "old son, put that back and use this"-he handed me a pack of 60 grit aluminum oxide paper. I asked if it was too rough, as I had been taught to use 400. He said the 400 was fine if had really like sanding heads. He said use the 60 and if I'm not satisfied with the results, he would finish it with the 400 for me. He also stated if it ruined the head, he would give me another. I had nothing to lose with that deal so I tried it. The head was pretty far out by initial sanding with 400 grit. Just enough done to see what it looked like. 20 minutes later with the 60 grit it was done and looked great. Saved at lot of time and wear and tear on the old arms.
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#38 JDBrian OFFLINE  

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Posted May 23, 2011 - 05:17 AM

Hey Billygoat, your friend was correct and I have the sore muscles to prove it. I was getting nowhere with 600. I used 320 to bring it down close, then I am going to finish it up with a higher grit. I could easily have used a lower grit. The gasket was replaced recently on this engine. I believe the new one failed because whoever did the work did not bother to level the head or properly clean up the block. There was a buildup of hard carbon on the block that very difficult to remove. I used a flat file backing up 120 grit to get down to the bare metal. I figured the gasket had no hope of making a seal on the ridge of carbon. I'm hoping that whatever problems this engine may have that a leaking head gasket will not be one of them. It has taken several hours to get it prepped.

#39 olcowhand ONLINE  

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Posted May 23, 2011 - 06:08 PM

Before I got my old Cincy end mill, I usually worked a head down with 220 wet/dry paper. Using wetted paper gives a smoother job, plus keeps the sandpaper from clogging as bad.

#40 JDBrian OFFLINE  

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Posted May 23, 2011 - 07:16 PM

I got the head pretty well flattened. I used 320 grit. I was busy today doing outside stuff but it only needs a bit of a go with 600 to polish it up. There were 2 spots that were low on the head. One was the area where the big leak seemed to be. The gasket was pretty toasted at that point and the block had a buildup of carbon that had to be sanded down to the bare metal. I have the PCV breather off and the valve train looks good. I need to check the gap on the tappets before it goes back together. I finally got all the goo out of the fins on the block. I'll soon be putting it back together.

#41 JDBrian OFFLINE  

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Posted May 28, 2011 - 10:26 AM

Ok I got the head ready to go. I went to check the valve clearance and the exhaust valve was OK but the intake was a bit high. I adjusted it but I find the tappet adjustment setup strange compared to OHC motorcycles. There does not seem to be a lock nut for the adjustment. Am I missing something or is it just a matter of holding the lifter with a 1/2" wrench and turning the tappet nut to get the correct clearance? Seems odd there is no locknut but there was a fair amount of resistance to the adjustment. I'm assembling the breather now with new gaskets, reed and filter.

#42 olcowhand ONLINE  

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Posted May 28, 2011 - 12:22 PM

No locknut, as the bolt is made for a tight fit. It won't move, so don't worry. Never had one to budge yet on it's own.
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#43 JDBrian OFFLINE  

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Posted May 28, 2011 - 07:23 PM

Thanks Daniel. I need to clean up the bolts and run a tap through the holes in the block before I install the gasket. I am finally starting to put the tractor back together. I have been cleaning and painting stuff as I go. Today I also got the steering gear greased and adjusted and installed some new bushings in the steering linkage. The steering is now pretty tight. I hate it when there is a lot of free play in the wheel.

#44 JDBrian OFFLINE  

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Posted May 31, 2011 - 09:53 AM

Got the block holes tapped out last night. I think I am going to replace all the head bolts as the existing ones are pretty corroded. I don't want a sticking bolt to cause a wrong torque reading and prevent the gasket from sealing. It's only a few $. Measured the cylinder and it still seems to be within spec. so it should last me a while.

#45 NUTNDUN OFFLINE  

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Posted May 31, 2011 - 10:00 AM

For the amount of work you are putting in to it I would go with new bolts also. Even without all the work you put in it new bolts would still be a good idea.




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