12hp engine problem....
 

I have almost completed my restoration, the tractor starts, runs & drives. Until today. It seemed as thought the engine was seized at first, starter would not turn it. I had to manually turn the engine with a strap wrench to loosen it up. with persistence, I was finally able to get it started. Once it was warm, it started no problem. After it cooled, same problem. Any Ideas? Clutch disengaged, oil full, starter ok. :bigthink:

Did you do any work on the engine before this happened?

I changed the head gasket & oil pan gasket. I removed and reinstalled the piston, did not replace anything. Just cleaned it out well.

Only thing I can think of is you may have a ring problem or you may have a rod seizing on the crank. You shouldn’t need a strap wrench to get it loosened up. Something is wrong and I strongly suggest that you stop trying to turn it over until you find out what the problem is because it will only get more expensive if you don’t. In my opinion the guys you want to talk to are Merk and Matt G. They have forgotten more about these engines than I know.

OK, thanks. I am new on here, is there a way for me to include them in this thread, or contact them?

I just find it weird that it is frozen when its cold, seems bass-ackwards...

You can PM them.

Not if the rod is seizing to the crank.

could you have put the rod cap on backwards? they are marked to only go together one way. also the oil feed hole in the rod needs to face the camshaft,

I agree with Don.

What did you tourqe the rod cap to? I remember making that mistake before

What do you think I will need to replace? Crank? Rod? Bearing?
Thanks for all of your help!

Should I plan on replacing one, or multiple parts?

I don't remember, other than it was something I found online somewhere.... Isn't everything on the Internet true?. Hahaha

I agree with Don and Merk...rod cap on backwards or whole rod in backwards. That should teach you to pay more attention to the service manual.

Nobody has a crystal ball to tell you what will need replacing...take it apart and see what happened. If you can clean the aluminum off the journal and have it still be within spec, you will get away with just a new rod, but no amount of speculation on our part is going to help.

I've found over the years that muratic acid works great for removing aluminum from cyl walls and cranks. just use it in a well ventilated area, keep water nearby to neutralize it , wear your rubber gloves and safety glass's.

Is the gas being shut off after use? Fuel could be seeping in causing extra pressure on the cold start. Just food for thought.

No. If the cylinder had that much gas in it, the engine would never start either due to hydraulic lock or the plug being totally soaked with gas.

Just saying, the fuel could be getting into the block through the rings causing causing similar problems the gentleman has described. This doesn't mean that the plug could be fouled if the fuel has a place to go. I have seen it dozens of times. Just food for thought.

It cannot get in through the rings...the bore is over an inch above the carb on these engines. If the needle and seat in the carb malfunctions on a K-series single, the fuel takes the path of least resistance out of the air cleaner. The only way for gas to get into the crankcase on these engines would be past the intake valve guide, and there's no way very much (if any) could go that way because the easy way out for the gas in this situation is out the atmospheric vent and out of the air cleaner.

If it was my tractor I would remove all items connected to engine...clutch, pto clutch and starter. Remove one at a time and try to spin the engine over. Maybe one of the above is causing your drag. I would remove the pto clutch first. If none ot the 3 is causing the drag on the engine you will have to take engine apart. When you remove the piston spin the crankshaft to see how free it is.

I had a Kohler K321 that made a noise after it ran a few minutes. The problem was the crankshaft bearing on the pto side. I've had a few that the bearing in the pto was bad and cause a noise and not leaving the pto clutch release.

Before you take the bearing plate off check to see how much crank end play is. A way to check crank end play is the way a Kohler manual shows.

You can download a Kohler manual from the site's Technical Library.

It is hard to tell what the problem is without having the tractor/engine in front of me.

Gotta be something wrong with the “ Piston re-install” if it was running OK before he replaced the head gasket, pan gasket both of which would have little or no effect on how it ran. Gotta be something to do with how the piston and rod went back in after it was removed and cleaned. Just my 2 cents.

I think Sam Mac is right, although, I will try spinning the engine after everything is disconnected. I guess I could of put the rod cap on backwards??? Someone mentioned the piston is directional too? That I did not know. Planning on digging in on Sunday. Thanks to all of you for sharing your expertise!

Yes, you have a good point. I was looking at my motor today and yes the situation presents as you have described. I was just hoping that he didn't have to tear her down again and could check the small stuff first. :beerchug:

It looks like you guys were right on all accounts... The rod cap was on backwards. I also noticed oil on the piston head (see pictures). The cylinder wall looks fine. Is there anyone in this conversation that is a parts dealer? So rings, rod, should I just do the entire piston? Is it necessary to go 10 over? I'd rather not, unless it is the consensus....

Thanks!
BP

Time to mic up the bore and rod journal. Where do you live in CT? If your close to Waterbury I know a good engine shop.

North Branford, about 40 minutes away.

This is the guy that used to build my race car engines

Bill Carlquist Carlquist competition engines 1-860-274-0742 in Watertown Tell him Sam McCleary sent you.

This is another option for you. A 12 for sale.

http://frederick.craigslist.org/grd/3546406534.html

Without you even measuring anything, I can see a pretty big gap between the piston and bore, so the piston is probably worn, but you'll have to measure it to be sure.

I agree with the guys here. measure up the crank and bore. check for out of round and taper. most mechanics usually will tell you once you remove a piston from a bore you have to at least put new rings on and hone the bore. reason, you probably have a slightly egg shapped bore that the rings are "fit " to from years of wear. you will never get them back in the same way. so they have to wear in again to fit and you'll probably have oil burning problems.