Kohler K321s, Rod and Crank repair.

[leo9]

After getting some good advice from Oliver I got the engine removed and pulled the oil pan to discover major damage to the piston, rod, and both balancing gears, something obviously came apart and it was down hill from there.

At this point I am looking at the crankshaft and the rod where it attaches to the crank and find what appears to be melted metal on both surfaces which, based upon other engines I have seen, would indicate a problem with the bearing, however in all of the research I have done I am unable to find any reference to a bearing. Does this rod have a separate bearing or is it simply a machined surface?

A follow up question then, is there any way to refurbish the crank without having to remove it or am I looking at a throwaway and full replacement of the crank, rod, piston and gears?

 

[sox3]

The Rod and crank are machine surface. If you can get a new rod they use to come n 10, 20 and 30 undersize
so you can have the crank cut to match. Parts are getting scarce for some of these units. You will need to pull the crank,
but they are pretty simple to remove. Just need a good machine shop to do the crank Check the piston and cylinder
for damage, rings also came in 10, 20 and 30 oversized.

 

[RandyT]

After getting some good advice from Oliver I got the engine removed and pulled the oil pan to discover major damage to the piston, rod, and both balancing gears, something obviously came apart and it was down hill from there.

At this point I am looking at the crankshaft and the rod where it attaches to the crank and find what appears to be melted metal on both surfaces which, based upon other engines I have seen, would indicate a problem with the bearing, however in all of the research I have done I am unable to find any reference to a bearing. Does this rod have a separate bearing or is it simply a machined surface?

A follow up question then, is there any way to refurbish the crank without having to remove it or am I looking at a throwaway and full replacement of the crank, rod, piston and gears?

Melted aluminum means lack of lubrication failure. The oil dipper could of broke causing the initial problem. Bearing failure caused by incorrect running clearances will should up very quickly after initial start of a new or rebuilt engine, normally within 5 hours, most likely within 1 hour. I have seen the same failure when the engine is run on excessive slope, more than 20 degrees, when the oil is slightly low. Dipper gets out of the oil when it flows to the downhill side of the engine.

 

[leo9]

Melted aluminum means lack of lubrication failure. The oil dipper could of broke causing the initial problem. Bearing failure caused by incorrect running clearances will should up very quickly after initial start of a new or rebuilt engine, normally within 5 hours, most likely within 1 hour. I have seen the same failure when the engine is run on excessive slope, more than 20 degrees, when the oil is slightly low. Dipper gets out of the oil when it flows to the downhill side of the engine.

Yes, I suspected a lubrication problem but the crankcase had plenty of oil, however, the failure did occur while I was climbing a hill although I was not on the hill very long. The dipper was broken but if it happened before or after we'll never know.

Thanks for your input.

 

[Gator6x4]

Bummer on your K321. That is an expensive engine to repair. The twin balance shafts are also a bear to re-install in the correct timing position. You may google Kohlers Web site and search for a SERVICE MANUAL. I would suggest attempting to locate the balance shafts used if possible. The cast iron block is boreable. New pistons and rods are available in oversize. I hope the crank is not damaged beyond repair. I would check with a machine shop before making any parts purchases or inquires.

I sunk $600.00 in a K321 25plus years ago and only purchased the piston, rings,rod, bearing, gaskets, etc. and had the block bored and the head trued. You may also consider exploring the cost of replacing the K321 with something else.

Good Luck

 

[leo9]

Bummer on your K321. That is an expensive engine to repair. The twin balance shafts are also a bear to re-install in the correct timing position. You may google Kohlers Web site and search for a SERVICE MANUAL. I would suggest attempting to locate the balance shafts used if possible. The cast iron block is boreable. New pistons and rods are available in oversize. I hope the crank is not damaged beyond repair. I would check with a machine shop before making any parts purchases or inquires.

I sunk $600.00 in a K321 25plus years ago and only purchased the piston, rings,rod, bearing, gaskets, etc. and had the block bored and the head trued. You may also consider exploring the cost of replacing the K321 with something else.

Good Luck

Have begun to think a replacement is the way to go if I can find one. Any suggestions as to alternative engines?

 

[Gator6x4]

Small Engine Warehouse has replacement short blocks for the K321 from $900.00 to $1,650.http://www.smallenginewarehouse.com...plier=Kohler&gclid=CKLVhuS93rMCFQU5nAodGGsArg. Type K321 in the SEARCH Box on the top left and click on search. A listing of K321 shortblocks will then display. For some reason I was/am thinking your engine was on a Power King. If you know a machinist that will not charge an arm and leg and will fabricate a adapter for you, one of the knock off Honda engines from HF may work. All kinds of problems can come from that some which include, motor mounts, throttle cable linkage, shaft size, etc.

 

[leo9]

That was quick. Your are correct my K321 is/was on a Power King.

Will check out the Small Engine Warehouse.

Thanks