Mower sounds like helicopter-HELP!


Old 09-09-07, 06:07 PM
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Join Date: Sep 2007
Posts: 5
Mower sounds like helicopter-HELP!

Hi! My parents have a Murray riding lawn mower purchased around 1995.
The model number is: 42819X92A. The MFG date- serial # is 94327- 027526.

On the engine the following numbers are:
14.5 hp OHV
Mod # 287707
Type: 0225 01
Code: 9408094A

Just wanted to get the numbers out first. LOL. Ok here's the problem. The mower was having trouble trying to start but since it did I assumed it was just a battery problem. It finally wouldn't start one day and upon checking a friend told us the teeth on the plastic ring gear (on the bottom of the flywheel) were missing or broken off. So we took the flywheel off, chiseled and pounded out the rivets and took it to the repair center to order a replacement. We also purchased the gear for the starter and the repair center put it right on the starter for us (we took the starter with).
When the part came in that friend wanted to put it back together for us so since he claimed he knew engines we left him. He put the new (metal) ring gear on the flywheel and tightened it down with the bolts they provided. Then it came time to put this mower back together. He put the flywheel down ontop of the shaft and put the key in the groove that lined up (I don't even know if that is how to properly do that). He then went about installing the fan part. Finally after the other parts were together he sprayed the big bolt with a spray that is supposed to help with rusting or sticking in case we had to remove it later (his idea) and put the big bolt that goes down that shaft in and tightened it down. The flywheel turned alittle bit when he did this. After assembling the rest of the mower I started it up. It started right up which was great. BUT--- now it sounds like a helicopter is right over your head--- it is very loud. It was never that loud in the years we have it. I went to cut around the yard since my grass is about a foot tall and i need to get it cut and i wore protective ear muffs to muffle the sound and i still got a headache. Also, some white smoke came out of the muffler followed by some sparks. It never did that before either. So i immediately shut it off because I didn't want to mess something up. Then smoke came out from under the black screen that covers that fan on top of the flywheel. It didn't do it when it was running- only when it was stopped. The oil level is good, new battery, spark plug. I cleaned the air filter and am waiting for it to dry because I seen here that a dirty filter could cause the smoke. But why is it that loud? My disabled father says it sounds like it is backfiring. It also now doesn't seem to have the "oomph" (power) that it had before this repair. Remember before this repair this mower worked great other than not wanting to start. What is going on? My dad is disabled and mom is laid off of work so we are trying to fix it without the huge repair bill. I don't really know much so as much details as you can provide is greatly appreciated. Thank you so much. WENDY
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Old 09-09-07, 06:40 PM
Join Date: Jan 2007
Location: MA
Posts: 514

Nice detailed description !

Others will chime in, I am sure but my initial thoughts are the flywheel was installed incorrectly and not tightened down to the proper torque.

You said your friend put the flywheel on and then the key. The key should be placed in the crankshaft keyway and the flywheel lowered down over it.

You said when he tightened the "big nut" and the flywheel turned a little bit. The crankshaft needs to be secured so the nut can be properly tightened. It needs to be VERY tight. I do not have the torque in front of me.

What it sounds like happened is the flywheel is loose and the key sheared or partially sheared and the engine timing is off. This would cause some of the symptoms you describe.
Old 09-09-07, 06:57 PM
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Join Date: Sep 2007
Posts: 5
Thank you so much for your reply. So what do i need to do now? Take the flywheel off, check and probably replace the key and reinstall it all over again putting the key in "before" the flywheel? Do I have to do anything else to fix this? Does it matter that the flywheel turned when he tightened the bolt? Would anyone know the part number for the key so I can check with my dealer-- makes it easier. If anyone knows this torque please let me know. I much appreciate it.

I am so mad cuz he claimed he knew what he was doing and he sure didn't. I have a bandsaw he messed up bad and don't even know where to go to get that going again so I wish we wouldn't have let him touch this. But financially its rough and i can't cut a 2 acre yard with a weed wacker so we let him.

Thank you for your help, i truely appreciate it.
Old 09-09-07, 08:28 PM
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It doesn't matter whether you put the key in first, or second. In fact, I always put the flywheel on, then the key, because it's so easy for the keyto fall out and get under the flywheel when installing the flywheel over it. That order of assembly makes no difference.

I do agree that chances are the key is partially sheared. The fact that the flywheel moved doesn't mean's going to move when you tighten the nut because you have to tighten it quite a bit. Unless you have it clamped in place, it will move. Do not put any lubricant or anything ont he tapered end of the crakkshaft where the flywheel goes or it will shear the key again.
Old 09-11-07, 11:26 PM
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Join Date: Sep 2007
Posts: 5
Hi and thank you very much for taking the time to help me. Our friend had the wheel puller and since we didn't want to get him involved in fixing it (or messing it up again) we were going to bite the bullet and take it to the repair center to fix. Fortunately before we could my neighbor came over and I was telling him what happened and he said he has a wheel puller and would take the flywheel off for us (we don't have one). So we left him in a last ditch effort to cut costs. He went home and came back with a bag of tools and took the flywheel off. Here, you both were absolutely 100 % right! The key was sheared off and the keyway groove was misaligned by almost 1/2 inch. We put the new key in and it was very tight and assembled the mower again. Crossing our fingers I tried to start it and it started right up! A few puffs of whitish/gray smoke came out of the muffler but then stopped. It is as quiet as the day it was bought. I ran it for 5-10 minutes and all seems ok. Since it rained I can't cut the grass to see if it has the power back but I am hoping nothing else was damaged from this incident. I'm keeping my fingers crossed. You both were right on the mark. Now hopefully I can find a forum that can possibly help me fix our Sears Craftsman band saw that the same guy messed up by doing some kind of adjustment to the motor.
Thank you both for helping me with this mower. I appreciate it bunches.
Old 09-12-07, 05:42 AM
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Join Date: Jul 2006
Location: USA
Posts: 306
Wendy- glad everything worked out. As far as your band saw there is a forum here for tools too just as there is for outdoor equipment and small engines. Go over there and post your problem and I bet you'd get the same good advice you got here. Let us know if you need help finding it.

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