Kohler K321 on a 1450 backfires and stalls.
 

Hello all, Thanks for the help so far with my 'new to me' tractor.

Yesterday, after mowing at full throttle for about 35 minutes, the engine will suddenly start to backfire badly, (Fire shooting out of the muffler.) and then stall.

It wouldn't start back up right away. It would turn over, but not start.

About a minute or 2 later, it would run again.

Could it be heat related? This happened last week after around the same amount of run time.

Thanks,

Mike

it could be your coil is going bad. check to see if its getting hot when the tractor is running. thats usually a sign of the coil going bad. your condenser might also need replacing.

I will check the coil for heat. Should it get hot right away if it is going bad?
Run the engine at idle or fast?

Is there a way to check it with an ohm meter?

Thanks,
Mike

wouldnt hurt to just replace it. and if your going to replace the coil you gots to replace the condenser. i think i paid around 40 bucks for a coil and a condenser from our sponsors. the one on there was original.

Hold up there, :bigthink:

Before changing the coil I would check the carb and make sure it is getting gas.
My 147 use to do that when I would go up my hill and my gas tank was low.
I gave it a rebuild on the carb but haven`t run low on gas since to see if it still back fires when I run out of gas under load. Kholers like to do that.
Next time it does that, check to see if you have gas at the carb. just to make sure.
It could be vapor locking to the 1450`s run a little hotter than the older mods.
Hate to see you buy a coil and not need it.
It`s also a good idea to check and make sure the mice didn`t build a nest between the eng and the tin also check the screen on the back of the engine to be sure it isn`t clogged up. Seems like no one checks there.
I guess thats it. Good Luck.
You should have seen the rats nest in my 1450
Fire shooting out of the muffler I forgot bout that, check the needle n seat. If that isn`t seating could be a problem too.
I hate it when that happens.
Oh yea when it stops check to see if you have spark if it don`t start up. If you are getting spark go for the above.
Don't jump to conclusions check it out before you run out and buy stuff you don`t need, but then it still wont run right.
I`m not saying it`s not the coil but check it out you can fix it faster that way, n get more seat time.

ole 147

Actually, I bet his exhaust valve is sticking. Try running a little bit of Marvel's Mystery Oil in your gas. Only about a cap full per tank. If it is your valve sticking, that should help.

AJ

+1 to what AJ said. I'd try the Marvel's Mystery Oil. If that doesn't help you may want to pull the head and see how it looks inside, ie carbon buildup and condition of the valves. I think if the coil was getting hot and going bad, you wouldn't be able to start the tractor until the coil cooled back down, about 30 minutes or so.

:BB&YS:

Another thing to check, before you run out and buy a bunch of stuff is if you have a compression gage another thing to test is the compression while it won't start. that will give you an idea if any valves are sticking. And above all check the SPARK PLUG......
Buying parts and stuff just cause it might be it, isn't a good way to fix engines. I'm cheap I don't like to buy stuff I don't need, cuts in to my play money.
Download the kholer manual for that eng if you don't have it. you will need it some time thats for sure and its free.
If you don't have a manual for the 321 here is a link to their site for the manual it's free this site also has a very good tech library.
http://www.kohlerengines.com/onlinec...1346_c_all.pdf

Sounds like a stuck exhaust valve to me.

Compression check is a little more complicated with the Kohlers due to the automatic compression release. You might need to use a manometer set-up. The Kohler manual describes how to use one - which you can make.

Good luck,
Bill

If it shot flames out of the exhaust, then it sounds like you backfired hard and have fouled the plug, so it definitely needs replaced. That's the least expensive thing to do to start with at first (buy at least two, just in case one fouls while you are trying to resolve your problem). Check your fuel line to your carb to see if it is getting pinched by the hood or squeezed so that fuel is not making it to your carb. Check your adjustments on your carb next--that doesn't cost anything and bad carb adjustment has been the cause of mine backfiring several times. Then, use the MMO in your fuel and see how that results. These are quick little checks that will help you to keep your costs down.

Cub Cadet 123

I bought the Mystery Oil. Just a cap per full tank is enough?

After it backfired hard, it did run fine on the same plug, but I am going to try a new plug tomorrow.

I have the coil, but maybe I will replace the plug, and use Mystery Oil, and see what happens.


How long will it take till the Mystery Oil will help?

The fuel line seems fine. In fact, everything was fine for the first 35 minutes.

I will report back what I did to it, and how it goes after mowing tomorrow.

Thanks a lot.


Mike:beerchug:

I think it says 1 oz/gallon.

Some add some to the oil too- maybe an ounce or 2.

I'd say mine ran much better after 2 or 3 tanks of fuel- and I wasn't having issues. I think it just helps clean out carbon + mine was way rich due to a plugged airfilter.

I would change oil at a more frequent rate using something that is detergent- I like Chevron Delo (30wt or 15W40).

Michael

Great, thanks. I hope the Mystery Oil is able to help my engine run better.
Looking forward to an 'incident free' day. I think she will be fine after a few more small fixes. Hoping not to have to pull the engine apart this year.

Mike

My 149 used to do that back in the late 1980's. You can't blame it on ethanol fuel, I do not think it was around then.

Mine was 100% repeatable, pushing snow with a 54" blade coming up my driveway at full throttle and as much hydro as the engine could take, after about 3 to 5 minutes it would backfire and quit.

The tractor would immediately restart, it would be able to run for the same 3-5 minutes before another backfire.

I had not learned about MMO back then, but, I learned to back off the hydro a little each 3 minutes or so, and it would not do the backfire/quit routine.

I still have that tractor, it hasn't ran since the mid 1990's. Maybe some day I will get it out and try the MMO to see if it will fix the tractor.

I did not quit using it because of a problem, I just got a larger tractor and parked the 149.:bigthink:

I had the same problem that you are having with my 149. After almost every stop if you just stood beside the tractor you would hear the exhaust valve snap shut when it cooled down. It would only be a couple minutes after shutdown, then it would start right up again. I removed the air filter cover and the filter. Put some MMO in a squirt oil can, run the engine about half throttle and squirt the MMO into the carb. I fed mine enough to almost choke it down, when it clears up a little do it again. I did that several times then reinstalled air filter and ran it a short time then I repeated the procedure. I run MMO in the gas now and haven't had a repeat of the problem. My 149 has been a great tractor with almost no issues in its entire life. I do have one advantage over a lot of owners, I bought mine new in 73.

Thanks
 

I spent a couple hours this weekend working on the tractor, and I was able to cut the lawn at full throttle with no issues.

I did replace the coil. The old one sounded like it had water in it and something was shaking around in it. Not sure if it was shot, but since I have limited time to work on it, I wanted to cover more stuff at once.

The back of the engine had dried grass clogged up in there. I scraped out as much grass and soot as I could with a screwdriver and shop vac'd it out. I would like to completely clean out all around the engine. The fins were clogged up with soot, etc as well.

What is the best way to clean it all up in there? Without taking the entire machine apart?

I changed the spark plug. The old one was really old. Gap at .030".

I put MMO in the gas and oil.

Ran really nice. Thanks for all the suggestions. Not sure which issue was causing the backfire. Maybe a little of all? OR maybe it will do it again. Hoping for the best.

Thanks,
Mike

It's a PITA to pull the engine to clean it but it's better to do it than having to pull it because you cooked it and have to clean it anyway. Kind of like the old filter add " You can pay me now or pay me later" I like to pull an air cooled engine every couple years and clean it.:beerchug: