My Tractor Forum banner
  • We have a new contest celebrating your backyard. Sponsored by Walmart, its your chance to win a $400 gift just in time for the 4th of July! HERE Contest Ends on the 30th.

1 - 20 of 20 Posts

·
Registered
Joined
·
269 Posts
Discussion Starter · #1 ·
Well, I finally tore into my 25HP Kohler Command motor I pulled out of a GT5000. Here's what I found. The #1 connecting rod was shattered. Cylinder walls were spared. The plastic oil pump gear was damaged. My manual doesn't show a repair part for just the gear, only the whole oil pump assembly. Also, the crankshaft bearing surface has what looks like melted aluminum on it. Probably from when the connecting rod got hot and shattered. Is there any way of safely removing this slag?
 

Attachments

·
Premium Member
Joined
·
5,747 Posts
That rod doesn't look overheated. Any chance the engine was running too fast? If it was a lube problem, the other rod should be bad also. Another thing that could have happened is failure of one of the rod bolts. Correct torque is critical on that engine, and varies if the bolts are new or used.
 

·
Registered
Joined
·
269 Posts
Discussion Starter · #3 ·
The guy I bought the GT from told me he ran it low on oil. He then told me the mower lost power, and that's when he realized the motor had no oil. He then changed the oil, but by that time it was too late. The connecting rod had already shattered. I think I can rebuild this motor. I want to rebuild this motor. I'm plan on replacing both connecting rods. The cylinder walls look clean, so I'll just deglaze them and replace the rings. The aluminum slag on the crankshaft bearing surface worries me. I'm hoping there's a way I can remove the slag without damaging anything.
 

·
Premium Member
Joined
·
5,747 Posts
Don't worry about the cylinders- they're way too hard for a hone. New rings and away you go. I have re-ringed many of these engines, some several times. Then I got smart and installed the cyclonic air filter assembly, which cost more than 2 pistons, two ring sets, and two head gasket kits.
 

·
Registered
Joined
·
108 Posts
Somewhere there is a post about using something caustic or an acid to remove the aluminum from a crank. It wasn't long ago, maybe two months. Try to search for that post. I think the OP did it and it came out fine! The aluminum can be "eaten" off without harming the base metal of the crank.

Well, the "kohlerman" already mentioned it but I found the post:

http://www.mytractorforum.com/showthread.php?t=130277&highlight=acid+aluminum
 

·
Registered
Joined
·
1,029 Posts
I would hone it- ive honed them their not that hard or else the rings WILL NOT SEAT! NO GOOD MAN! If you take Muratic acid, soak a ra with it and rap the acid soaked rag around the crank, and the aluminum will "melt" right off, also check your ring air gap. The right cylinder is always worse compression wise- not sure why, something with that cylinder being higher than the other side- less lube. Also make sure to use either during honing as a lubricant and wash out the block with soapy water until the cylinder walls turn a greyish rustic color- get all the grit out. Hope this helps!
 

·
Registered
Joined
·
1,029 Posts
I would hone it- ive honed them their not that hard or else the rings WILL NOT SEAT! NO GOOD MAN! If you take Muratic acid, soak a ra with it and rap the acid soaked rag around the crank, and the aluminum will "melt" right off, also check your ring air gap. The right cylinder is always worse compression wise- not sure why, something with that cylinder being higher than the other side- less lube. Also make sure to use either during honing as a lubricant and wash out the block with soapy water until the cylinder walls turn a greyish rustic color- get all the grit out. Hope this helps!
Wrap the journal only- stay away from bearings as it will rust them.:trink39:
Any questions let me know- im KOHLERMAN for a reason- hahaha
 

·
Registered
Joined
·
269 Posts
Discussion Starter · #8 ·
Here's a pic of what I'm dealing with. I'll try the muratic acid advice. We sometimes use it at work to clean off spilled concrete from our trucks. I don't like to use it cause it stinks soo much. My dad told me to use an emery cloth to clean off the aluminum slag.

Why would anyone use either to lube the cylinder walls when honing? Isn 't that stuff flammable?
 

Attachments

·
Registered
Joined
·
261 Posts
When using hydrochloric acid to dissolve aluminum, hydrogen gas is released. Hydrogen doesn't burn so much as it explodes. Keep open flames/sparks away from the fumes.
 

·
Premium Member
Joined
·
5,747 Posts
Contrary to what others have suggested, I have re-ringed many of these engines without honing the cylinders, and always with good results. I had one that was uning three quarts of oil per day. Also, keep in mind that these cylinders are hard plated, and you don't want to hone through that. IMO, that and the hydraulic lifters are the only premium features in an otherwise mediocre engine.
 

·
Registered
Joined
·
246 Posts
You might want to consider a new oil pump, since it could have damage from running dry. You wouldnt want to do all that work, then no oil pressure.
 

·
Registered
Joined
·
269 Posts
Discussion Starter · #12 ·
I already plan on replacing the oil pump, it was damaged when the connecting rod broke. The plastic gear on top was damaged. I added up the cost of new parts, and it'll cost about $212 before taxes and shipping.
 

·
Registered
Joined
·
1,029 Posts
Using Fast Start- Ether i am sorry- spelled it wrong when honing keeps the dust down, lubricates the stones while oil will not let the honing stones hone. We use it every time we rebuild engines at our shop- we have bean in buisness for over 30 years, and rebuilt hundreds of engines, so it works- try it! Emery cloth will work as well, but will also take the polished surface off the crank, the cranks are turned and polished. I would also consider replacing both rods, and make sure the crank isnt out of round.... If it is out of round, or oval shaped, it will again, toss a rod. If it was me, i would replace both rods, turn .010 under crank, under size rods, bore cyls 10-20 over *whatever it needs* and all new gaskets. With all that done, you know your starting back up with a "new" motor. Good luck, hope you get it right.
 

·
Registered
Joined
·
1,029 Posts
Contrary to what others have suggested, I have re-ringed many of these engines without honing the cylinders, and always with good results. I had one that was uning three quarts of oil per day. Also, keep in mind that these cylinders are hard plated, and you don't want to hone through that. IMO, that and the hydraulic lifters are the only premium features in an otherwise mediocre engine.
3 Qts of oil a day? That is pretty bad! Wow. Hard plated. hmm. I have honed them with no prob. I may try the easy way without honing.. time saver. And yah those motors are pretty mediocre, they are like those crappy rod throwing worthless briggs v twins. Who the heck would think of using 1 journal for 2 rods? Stupid engineers. The good motors were the magnums, k series, onan cast irons, briggs opposed twin, 2 journal cranks, some of the wisconsins,those were the legendary motors. Not these new junkers. Throw away, aluminum lightweights.
 

·
Premium Member
Joined
·
5,747 Posts
The engines I was referring to were used on stump grinders, the worst thing you can do with an engine. They originally had the standard air filter assembly, rings would last about 300 hours. Then I got smart and replaced them with the optional cyclonic air filter assembly, and that solved the problem. Prior stump grinders with the Onan Performer 20 engine were more forgiving of abuse, but still suffered the same affliction. A customer who bought one of my used ones ran it out of oil several times, I would put a wrench on the flywheel nut and break it loose, and it would keep going. He used to do that with all his equipment.
 

·
Registered
Joined
·
246 Posts
3 Qts of oil a day? That is pretty bad! Wow. Hard plated. hmm. I have honed them with no prob. I may try the easy way without honing.. time saver. And yah those motors are pretty mediocre, they are like those crappy rod throwing worthless briggs v twins. Who the heck would think of using 1 journal for 2 rods? Stupid engineers. The good motors were the magnums, k series, onan cast irons, briggs opposed twin, 2 journal cranks, some of the wisconsins,those were the legendary motors. Not these new junkers. Throw away, aluminum lightweights.
Pretty sure all Vtwins use one journal, opposed twins use two.
 

·
Registered
Joined
·
1,029 Posts
Well, every V8 automobile I'm ever torn down uses that design. Seems to work well for them!
I dont know what to tell you people/ i try to help and all i get is crap. I dont care what you people say, just quit whining and blowing smoke. Ive had it. And good hope automobiles work good with that, and they do. Im pretty sure a lawnmower engine isnt an automobile??
 

·
Registered
Joined
·
1,029 Posts

·
Registered
Joined
·
403 Posts
I would clean up the bore but watch there's not much metal on those sleeved aluminum block engines.

I just cleaned and polished a K301 kohler crank the other day.It was in about the same shape as yours.I used a small file to take it down close then got out the old 220 grit sand paper to take it down till there was a slight glassing of aluminum left,then I used a Medium grit Emery Cloth Wet and finally to polish it I used a 001K Crocus Cloth paper wet.

http://products3.3m.com/catalog/au/...asives_3_0/command_AbcPageHandler/output_html

It turned out really nice.
Looked like a mirror when I was done.
The Crocus Cloth is really nice for the final polish.
 
1 - 20 of 20 Posts
Top