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I'm having mysterious problems with my pushmower. I've tried several things but I can't figure it out. I'm reasonably mechanical - rode and worked on dirtbikes most of my life. I spend most of my time on dirtbike forums getting mechanical advice and sharing information.

I figured I'd easily be able to figure out this mower but it's got me stumped.

Backstory

The mower is about 5 years old and probably has 100 hours on it.

It always ran well and alway winterize it. In the spring it gets fresh oil and a blade sharpening.

This year it started running really rough, like there is a miss in the engine or a timing problem.

What I Did

I've replaced the plug with a new one, I've taken the carb off and completely cleaned it - float bowl, needle, etc. I also replaced the gaskets so there would be no air leaks. It ran well tonight and my wife did the back and 1/3 of the front (she uses it as a cardio workout) when it started to run badly. I watched the whole process because I wanted to see how the mower was running. Just as I was about to clap myself on the back, I started hearing a slight miss in the revs, very slight but enough to make me wonder. Then, my wife hit a branch and it started to sputter and miss really badly. It didn't recover. It took 4 or 5 pulls to get it to start and from that point on it had a serious miss and it was running poorly. It ran for another lap around the yard but then quit again. I couldn't get it started at this point and will try again tomorrow.

What I Think it May Be

I'm thinking three things:

1. The timing key is damaged but not sheered? It's not in perfect condition and when the blade hits something it throws the timing off slightly? I have no idea...

2. The plug gap is not set correctly? I can get a gap tool tomorrow and make sure it's in spec.

3. The valves are acting up - maybe one is sticking or out of spec (if it's not running smooth?)

Any suggestions, help, comments or questions are all welcomed and appreciated.

Thanks in advance!

D

I would start by looking at the flywheel key. Even a slight shear can cause timing and running problems. Hitting something will make it worse. Don't forget to properly torque the flywheel back down after checking.

That's the first thing I will check in the morning. Thanks for the reply. I will be sure to post results - nothing worse than an un-concluded repair thread.

I got down the to flywheel and realized I don't have a puller. I was going to use a ore unsavory method but then got nervous and didn't do it for fear I would damage the flywheel...

I'll give an update once I borrow a puller.

FYI - I tried starting the mower this morning before I worked on it but it would not start. Interested.

D

Sometimes you don't need a puller just to check the key and maybe you can look straight down from above at where the crank key way matches up with the flywheel key way. You may have to remove a large nut or manual starter mechanism but you just may get lucky and not have to remove the flywheel to check the key. However, sometimes you find that the key is only slightly sheared and only by removing the flywheel will you be able to tell.

Thanks for the tip - I could not tell if it was sheared.

I suspect that it is only damaged as it's running very poorly.

I've completely pulled off the carb, cleaned everything and replaced the plug but I'm stumped. I figure this is the last major thing that allows it to miss, pop and run so roughly.

D

REPAIR UPDATE - Opinion needed!

I'm in a leg case (damn dirtbikes!) and it's making it hard to work on the mower so I decided to bring to mower to my local shop and see what they think.

They called today and told me that the key is damaged but it also damaged the flywheel. I haven't seen it but it makes me wonder - how does this situation damage the flywheel?? I thought that's what the key if for - it lets go before the flywheel is damaged.

So they are saying a flywheel is $80 plus $65 labor - roughly $165 after taxes.

Now, this mower isn't worth more than $275 new and a used mower I can get for less than $165.

What does everyone think?

a) Pick up the mower, order the part and do it myself?
b) Buy a used mower and scrap this one?
c) Have them fix it?

Opinions welcomed!

D

I would pick it up as is, don't have them put the flywheel back on. Have them show you how the flywheel is damaged. When you get it home you can explain what they said and we will tell you what we think. We have a repair shop in the area that always try's to over sell on parts. You may be able to savage. If not look around your area for a used flywheel, if it is a popular model someone should have one. I think you should be able to repair yourself if you have a torque wrench. Just my opinion.

Rivets said:

I would pick it up as is, don't have them put the flywheel back on. Have them show you how the flywheel is damaged. When you get it home you can explain what they said and we will tell you what we think. We have a repair shop in the area that always try's to over sell on parts. You may be able to savage. If not look around your area for a used flywheel, if it is a popular model someone should have one. I think you should be able to repair yourself if you have a torque wrench. Just my opinion.

Click to expand...

I like this idea - I have a feeling that they are trying to oversell me on a part. I would be surprised if the flywheel is damaged - isn't that what the key is trying to prevent? I'll grab it, take a few pictures and go from there... I have a torque wrench and reasonable mechanical - it's the leg that's making things difficult.

scotiadallas said:

I like this idea - I have a feeling that they are trying to oversell me on a part. I would be surprised if the flywheel is damaged - isn't that what the key is trying to prevent? I'll grab it, take a few pictures and go from there... I have a torque wrench and reasonable mechanical - it's the leg that's making things difficult.

Click to expand...

I'd sure like to see some pictures, too. Please post some detailed pictures when you get it back from the shop and make sure to have them show you exactly what is damaged on the flywheel.

FIANL UPDATE: Cub Cadet Pushmower (11A-18MC596)

Hi All, I went to pick up the mower today and see what was going on with the flywheel. It turned out they were right - the timing key wore away the inside of the flywheel and it was turning slightly in it's housing. Inside the flywheel there was a clear wear pattern and even with a new timing key, the flywheel would still turn slightly and throw off the timing.

I tried to cut a deal with them for a new mower and they offered $50 for the old mower which I thought was fair. The problem was all the new mowers were $250 plus. Too much for me as I already had a $100 mower lined up with a local small engine repair hobbyist providing I would give him my old mower.

I felt better about that arrangement than buying a new mower. That said, on the way to pick up the used mower, I looked up the flywheel part for the CC mower and the cheapest I could find it was $80. That sealed the deal for me and put my mind at ease.

Anyway, the deal is now done, I've got a 22" deck with a 4.0 B & S engine on top of it. We cut the looong overdue grass tonight and it worked like a dream.

I wanted to post an update for everyone who was wondering the end of the story...

D