flywheel rubs something?

weedmower · May 15, 2017

I have a Craftsman 4.5 HP push mower [model #11A-416H729] that wouldn't start after the rainy season. The spark plug looked ok, but I changed it anyway since I couldn't see a spark. I also replaced the coil and set the gap as specified. I topped off the oil even though it was just a tiny bit low. I also replaced the air filter which was filthy. Then I cleaned the carburetor and cleared one of the holes that was blocked. I reassembled it...and it still won't start.

I did notice that the flywheel when turned manually made a horn-like sound and seemed to rub something in one spot. I checked that the coil wasn't touching, nor any of the covers and, without taking any more of it apart, looked down below where the blade is, but still couldn't see anything else rubbing. There was some plastic string from a tarp wrapped around the blade axle, but removing that made no difference.

Is there something else I can try? Perhaps after cleaning the carb, it reclogged from the old fuel? I'll try recleaning, but if there's something obvious I haven't done, let me know please.

ILENGINE · May 15, 2017

When you cleaned the carb did you clean the bowl nut. The horn sound would be the air being pushed out of the cylinder or being drawn in. Nothing unusual there. The rubbing should create a shiny spot where it is making contact. Also did you recheck to make sure you had spark after replacing the plug and ignition module.

weedmower · May 15, 2017

I cleaned the bowl nut. I see shiny metal all around the the base of the flywheel, but can't see anything that is touching it there. I don't know if there's a spark. I don't have a spark plug tester. If I remove the plug, ground it on the frame and then go behind the mower to start it, I can't see the plug clearly enough to see if there is a spark (I'm working alone here). After cleaning and reassembling, I did hear the motor start to turn over once, but than nothing. I assumed since it tried to start, it had a spark, especially since it's a new plug. I could try to look for the spark again.

One thing that worries me is the new coil didn't have anything to indicate which side should be outwards. Is there a way to tell which way it should be installed? My old one had writing on it to indicate which way it should go. The new one is a compatible, so it looks different and has no writing.

ILENGINE · May 16, 2017

The tab that the grounding wire connect to goes toward the engine, so it is below the module.

weedmower · May 16, 2017

Thanks. I'll check when I get home.

bertsmobile1 · May 16, 2017

If you bought the coil from a real mower shop then take it back & get it checked.
If you bought a cheapie off the web then god chance it is the wrong one or a rejected part that got put back in the parts stream.
Down here mower parts are near 3 time the USA price and I have customers comming in all the time with "new compatiable " parts that are either the wrong part or were faulty from the start.

weedmower · May 16, 2017

Okay, I got home and checked the orientation of the coil. It was upside down. I turned it over and gave the string the ol' heave ho and...nothing. It gave a little sputter like before as if it was trying to start, but just once. More pulling got no sound at all except cursing from me. It sounds like it's starved for fuel. By the way, the horn sound occurs when the fly wheel feels like it's rubbing on something. I just don't see anything. The shiny metal I saw around the base of the flywheel is from the brake. I don't care about the sound so much as the fact that the fly wheel won't turn freely in one spot.

@bertsmobile1: The first coil I got was a compatible that wouldn't even fit on my mower. I will return that one. The second one off of Amazon is also compatible, but at least it fits the bolt holes on the mower. I kind of regret that I went for the cheaper one now, but I'll see if I can see a spark on it and if not, return that too. Live and learn.

This weekend I'll try cleaning the carb again. Maybe I missed a hole. Thanks for the advice, guys. I need all I can get.

bertsmobile1 · May 20, 2017

weedmower said:
Okay, I got home and checked the orientation of the coil. It was upside down. I turned it over and gave the string the ol' heave ho and...nothing. It gave a little sputter like before as if it was trying to start, but just once. More pulling got no sound at all except cursing from me. It sounds like it's starved for fuel. By the way, the horn sound occurs when the fly wheel feels like it's rubbing on something. I just don't see anything. The shiny metal I saw around the base of the flywheel is from the brake. I don't care about the sound so much as the fact that the fly wheel won't turn freely in one spot.

@bertsmobile1: The first coil I got was a compatible that wouldn't even fit on my mower. I will return that one. The second one off of Amazon is also compatible, but at least it fits the bolt holes on the mower. I kind of regret that I went for the cheaper one now, but I'll see if I can see a spark on it and if not, return that too. Live and learn.

This weekend I'll try cleaning the carb again. Maybe I missed a hole. Thanks for the advice, guys. I need all I can get.

I wrote this a while back and to save a lot of typing copied it here.
Read it an take what you need form it.

Lawn mower diagnosis 101.
Get an in line spark tester or better still a colortune and fit it
Get a can of starter fluid.
Remove air filter, give the mower a shot and try to start it.
If it starts but will only continue running is you keep giving it short shots of starter fluid the you have a fuel problem

If the colortune / spark tester does not flash or stops flashing before the engine starts to die, you have an ignition problem.

get a temporary fuel tank
Hook it directly to your carb and hold it as high as you can above the mower to give you the best head pressure.
Runs OK then you have a fuel line problem
No difference then you have a carb / manifold / valve problem.

Hook up the original fuel line again , start the engine & keep it running with short shots of starter fluid.
With a TRIGGER bottle of water/ Wd40 etc liberally spray all around the intake manifold.
Engine speed changes = air leak

weedmower · May 22, 2017

I wish I'd seen this earlier. For some reason, the notification went straight to my spam folder. I finally figured out the problem. You were absolutely right about the second "compatible", bertsmobile1. It wouldn't spark for me. So I put the old one back on, recleaned the carb and found a plugged hole that I missed the first time. But even after clearing that, I couldn't get it to start. Eventually I realized there were air bubbles in the fuel line that prevented the fuel from flowing. Once I squished the primer bulb about 30 times, I was able to eliminate the bubbles. It runs fine now. Thanks for your help!:smile:

flywheel rubs something?

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