782 with 18 horse magnum starting issue

[heinriech]

Hey all been a while since I posted. I did a brief search but didn't come up with much. I am trying to get my equipment ready for what looks like a heavy snow winter. The cub seems to have multiple issues that are plaguing it.

Background: The tractor has been increasingly hard to start for the past 6 months. Lots of fiddling with the throttle and choke. Putt once then crank again for a while, another putt, after 3-5 minutes worth of it will finally take off with an abundance of smoke out of the pipe. On top of this there is oil leaking from somewhere, haven't tracked that down.


This weekend went out to get it running. Charged battery, checked oil, put a gallon of fresh gas in. Rolls really slow and typical putt, every once in a while. Tried starting fluid, that only created back fire out of the exhaust. Tried gas into the carb same back fire out of the exhaust. Pulled the plugs before starting fluid and gas in the carb. The plugs were a little crusty but nothing saying I don't have fire, wire brushed and put back in. Notable point they were bone dry, no gas on them. I did try another battery and didn't roll any faster. I did roll the engine with the I need to review the grounds to see if this is an issue.


I am starting to ramble so I will cut it off. Just want to see if any of the professionals here to provide some guidance on what to do next to get old girl going again:
Check grounds?
Rebuild starter?
rebuild carburetor?
verify fuel pump works?
rebuild engine?
full restoration?

Thanks for any and all help.
Jason

[cooperino]

Ok. When was the last time it ran well?

This could be a fuel issue or could be worse. Do you have a compression gauge?

If you have good compression i would say fuel issue. Crap in carb or in fuel lines and filter.

[Gompers]

M18 is magneto ignition, so it's unlikely to be an ignition system problem unless it's with the ignition module itself. Plus you're getting spark since things are burning when you shoot fluid into it.

First thing I'd be suspect of is the battery/starter. Have you tried jumping it with a bigger battery? I know you said you tried a different one, but if it's not big enough it won't matter. If it doesn't spin over fast enough, often it won't fire. They tend to spin over slower in the winter too since the oil is so much thicker and it's gotta spin the maple syrup in the rear end as well.

[Cub Cadet 123]

Good to hear from you again!! Great advice given already! If it has been stored outside, then definitely check grounds and battery terminals. Sounds like a carb/fuel issue. If you want a quick fire, then you can try Mechanic In A Bottle (sparingly), but you will likely have to rebuild that carb. Keep a trickle charge on that battery if it is very cold in your area. I would change those plugs, too. If you want it to be reliable and you found them to be encrusted.

Cub Cadet 123

[Gompers]

Originally Posted by Cub Cadet 123

Good to hear from you again!! Great advice given already! If it has been stored outside, then definitely check grounds and battery terminals. Sounds like a carb/fuel issue. If you want a quick fire, then you can try Mechanic In A Bottle (sparingly), but you will likely have to rebuild that carb. Keep a trickle charge on that battery if it is very cold in your area. I would change those plugs, too. If you want it to be reliable and you found them to be encrusted.

Cub Cadet 123

Carb clean/rebuild/replacement would probably be the second thing I'd look at, but if it's not running on brake clean or starting fluid or whatever, I'd lean more towards something in the starting system.

The only real way it could be a timing issue is if you have a sheared flywheel key.

I had a M18 that started about the same way until I put a bigger battery in it. Fires right up every time now with the newer/bigger battery. GT batteries never seem to last long.

Could maybe use a good cleaning of terminals/wires on the battery and solenoid and whatnot. It's a fairly long run from the back of the tractor up to the starter.

Also keep in mind that the M18 doesn't need power to run. The magneto needs to be grounded to shut down. You can check to see if any of that is a problem by just disconnecting the engine wiring harness from the tractor (though I have no idea how you did the conversion from KT to Mag so it might not be that simple).

[john hall]

Originally Posted by Gompers

M18 is magneto ignition, so it's unlikely to be an ignition system problem unless it's with the ignition module itself. Plus you're getting spark since things are burning when you shoot fluid into it.

First thing I'd be suspect of is the battery/starter. Have you tried jumping it with a bigger battery? I know you said you tried a different one, but if it's not big enough it won't matter. If it doesn't spin over fast enough, often it won't fire. They tend to spin over slower in the winter too since the oil is so much thicker and it's gotta spin the maple syrup in the rear end as well.

What he said, a Magnum has to spin pretty good--at least the one in my 1811 anyway. Throw some jumper cables/booster box on it and see what happens. It takes enough RPM to make the magneto ignition work properly.

[ol'George]

Originally Posted by john hall

What he said, a Magnum has to spin pretty good--at least the one in my 1811 anyway. Throw some jumper cables/booster box on it and see what happens. It takes enough RPM to make the magneto ignition work properly.

That is my findings on the magnum magnetos also.
A few years back I had to replace a magneto on my M-18 mowing tractor as it quit working.
So I purchased a inexpensive one from ebay.
During the summer it worked and works fine to this day.
But
In winter, anything below freezing it loses spark because of the slower cranking speed.
I tried a 420 CCa battery and it gives a few degrees lower starting ability but still sub par.
What does help is .020 plug gap and I ran another positive cable to the starter as well as another from battery to ground.

That noticeably helped.
I initially was going to run larger gauge cables then thought why remove the ones already there,so I just run the new ones right along side, it works, was easier, and is an over kill that hurts nothing.

I have since put to use my other 782 with cab & thrower for winter duty, so the mower tractor sees only summer duty of approx 80 hrs per year.
just my findings.
FWIW the winter duty tractor has OEM kohler mag coil and has not failed to start at *10, as that is about as low as I remember needing to start it.
Both use the same lube/hydro oil and both engines are in good condition.

[Gompers]

Originally Posted by ol'George

What does help is .020 plug gap and I ran another positive cable to the starter as well as another from battery to ground.

That noticeably helped.
I initially was going to run larger gauge cables then thought why remove the ones already there,so I just run the new ones right along side, it works, was easier, and is an over kill that hurts nothing.

Did you try both of those at the same time? Curious if one or the other made the bigger difference.

As much as (I think mostly uninformed) folks like to bag on the KT17, those things pop right off even when it's -10 out. Definitely an easier to start engine than the Mags.

One thing CCC did right in the cyclops was going to the automotive style battery. That helps a good deal, IMO.

[heinriech]

Thanks for input guys! It’s probably been 6-8 months since it has started well. As far as running after it started, just about a month+ ago when I mowed last. I did put an automotive battery (smaller) but still didn’t show a noticeable difference in cranking speed. I will try that again. I also have a 16 volt automotive battery out of the race car that should kick it in the butt. Another item to note is the plugs are gapped at .043”. So not sure if that may be the issue. What do you recommend for new replacement plugs?

[R Bedell]

The Kohler Magnum Service Manual states the Plug Gap should be .035". You need to re-gap your plugs to specifications.

See if that improves your starting.