M 18 vibration
 

I picked a 782 with a M18 in it yesterday. PO said the carb needed attention so I took it off and give it a good cleaning and put it back on. Got the tractor started and it vibrates and shakes pretty bad at idle or full throttle. I was thinking maybe it was missing out on one of the cylinders so I pulled one spark plug wire off and it died ,I pulled the other spark plug wire off and it dies. I'm talking about dies not just missing out. What to heck is going on . This is my first experience with a m 18 ,so this is new ground for me. Can you guys tell me what is going on?

I would bet the carb is junk. You might try to rebuild it but if it has the Walbro, it probably won't work. I say it's the carb because my 582 with a M18 was running terrible until I richened up the fuel mixture and it cleared it up immediately. Problem with the Walbro carb is that it's not adjustable. Best solution would be to find a Kohler adjustable carb from a KT17 and replace the one you have.

AJ

I have been trouble shooting two mag 18's.
The first one ran rough and would smooth out with a lot of choke. I cleaned the carb twice - no go, put in a carter with adjustable load needle and it runs nice and smooth. The second Mag ran the same at first. I cleaned out the carb bowl (full of snot) now runs good.
Hopefully all yours may need is a cleaning.
Dan

I agree. Those Walbro's are hit or miss. Sometimes a cleaning can get them to work, other times you have to eat the bullet and throw them in the garbage.

For the OP's info, the Carter carb that badboy mentioned is also known as the Kohler carb or at least they are the same carb. I want to say that Carter started making them for Kohler and then Kohler starter building the identical carb them themselves.

The rebuild kits for the Carter/kohler carbs are the same. The Walbro rebuild kit is different.

AJ

Maybe I shouldn't have used the word vibrate , I should have just said SHAKE. This thing shakes so bad the seat jumps up and down, you think it's going to shake the open hood off and it looks like it might shake the muffler shroud loose. It's almost like part of the flywheel is missing. And the other thing I don't understand why it tries to die by just pulling off either one of the plug wires. The carb I have on it is from a kt 17 I already had because I had read on here that the walbros were not too good and that's what the PO gave me. (a walbro allready off) All I did was give my carb a really good cleaning and put it on. I can see it running rough from a carb that's out of adjustment or needs rebuilt but this thing runs ROUGH. Below is the carb I put on. I sure appreciate the help. Thanks Gary,

Attachment 29885

Is the driveshaft running straight and true?

I never thought to check. That would be a good thing to look at beens the engine is a replacement and obviously the driveshaft was delt with. I'll check and let you know.

Well the driveshaft was not the problem. I took the driveshaft clear out and it still shakes. What I did discover is that it totally dose not fire on the right side. After running awhile the plug on the left got warmed-up and the right spark plug was still cold. I switched plugs and even tried other plugs with no succsess. It is getting spark but dose not seem to be real hot. Actually neither side seems to be real hot for that matter. Could it be a poor engine ground? The right side is for sure getting gas, as the plug was wet with gas when removed. I took the intake manifold off thinking that maybe a mouse had moved in since I don't know how long the carb had been off before I bought it,but all was clear. While I had the manifold off I turned the motor over and I could see the valve moving as it should. Did I read on here one time that these engines can throw a magnet off? I may be reaching here but I'm all out of ideas. It wouldn't be too hard to pull the engine at this time and check for a throw magnet, because I took the bolts all out of the engine mounting plate to remove the driveshaft and have not replaced them yet. Thanks for your help guys, Gary

P.S. I,m going to blow leaves now and give this some more thought.

with the plugs out do you have compression on both sides? is the starter disengaging from the flywheel after starting?

Are you sure, that the Motor is ok? My red MTD 1984, 782, with the KT 17 S2 had the same Problem, as i got it 2008 from the States. The Engine was running, but it had a extrem shaking. I looked at the Carb, Ignition, Spark Plugs, and so on, the Problem was the same, no Solution.

After this all, i removed the right Cylinder Head, and saw, the Piston doesn't work, after removing the Cylinder, i saw, the broken Rod, the Engine was running on one Cylinder, the right Side was dead.
Broken Rod, broken Piston, broken Cylinder Wall, scratched Rod Journal, but no Hole in the Block.

I rebuildt the Block, got Piston Rings, Undersize Rods, Crank Bearings, Fuel Pump, Carb Kit, and Gasket Set, new from an ebay Dealer, in the States. Some used Parts, Piston, Cylinder, i got from an occ User, for free. (Much Thanks Scott).

I brought the Crank to an Engine Shop to turn over. The Engine is running now, how new, and i'm glad to rebuildt the Engine, it's powerfull and runs great,

mfg Georg,

Right side zero compression. That's not
good.....

If you are saying you have no compression on one side, it 'prolly broke a rod.
Pull the head to see if the piston is moving.

I will pull the head first chance I get. After messing with it most of the day I'm done with it for now. The PO promised to compensate me some on what I paid.

The 782 originally came with a series 1 KT, they had oiling problems, and if not properly cared for died an early life.
Many have been converted to series 2, or better yet magnum series engines.
You could be lucky and just have a stuck valve.
If you pull the spark plug and carefully insert a piece of coat hanger bent
90* 1/4- 1/2" from end or so facing the piston you should be able to feel the piston touch it as you turn it over by hand
this would tell you if it is a rod broke and the piston is not moving or a valve hung.
Something easier, is if you crank it with the starter and put your finger in the plug hole and feel absolutely nothing, the piston is not moving.
If you feel slight compression it is usually a valve (or a hole in the piston)
I feel your let down BTDT.

Here you can see the Thread of my 782 Engine,

http://www.onlycubcadets.net/forum/showthread.php?t=113

Bummer news on the rod I hope not much more damage has been done to it.

Thanks for asking Methos but I haven't had time to tear into it. Been work'n,hope to get a closer look soon. I did put my finger tight over the spark plug hole and there is no compression, while turning the engine over with the starter. I can see the valves moving by looking in with a flashlight.

What have you done with the Engine, os it open now?

mfg Georg