Problem with 1978 5278 pull start mechanism

modernclassic

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I have a 1978 Lawn Boy 5275. Runs great.


I have a problem. The pull start cog can't engage with the flywheel teeth because the flywheel is too low or the pull start cog is too high. The starter moves over appropriately when pulled and moves back when release. The ()#@*$@)(*$@ starter cog just doesn't have the clearance to engage.

Here is a picture of what is happening.

ZzfPQy2h.jpg


Can someone help me fix this?

First post to this forum.


Thanks,
 

Lawnboy77

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More than likely the crank has been bearing down on the crankcase. Check the crank play is excessive, not side to side, but up and down. If excessive then I would replace the crankcase. The crank should be good since it's cast iron, all the wear will take place on the bottom, inside surface of the crankcase.
EDIT: Shims or thrust washers would be another option, but putting a good crankcase in the mix would be best. Some previous owner probably ran without air filter in place and got grit in there causing premature wear.
 
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modernclassic

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More than likely the crank has been bearing down on the crankcase. Check the crank play is excessive, not side to side, but up and down. If excessive then I would replace the crankcase. The crank should be good since it's cast iron, all the wear will take place on the bottom, inside surface of the crankcase.
EDIT: Shims or thrust washers would be another option, but putting a good crankcase in the mix would be best. Some previous owner probably ran without air filter in place and got grit in there causing premature wear.

I'm interested in the shim route. What kind of shim does one use?
 

Lawnboy77

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something like this. The later F series engines addressed this issue and included these thrust bearings and washer to prevent what you are going through. Measure your play for me, I may have something I can set you up with.
 

modernclassic

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something like this. The later F series engines addressed this issue and included these thrust bearings and washer to prevent what you are going through. Measure your play for me, I may have something I can set you up with.


Thanks for the pic and the offer. I assume I'll have to tear the motor apart to get that measurement fore you? It may be awhile before I have time to do that.
 

Lawnboy77

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No problem, glad to be able to help. Ah don't worry about sending any measurements, I'll just send you what I have, which is what you see in the pic and you can add or take away to get a good end play. Just pm me with your address and I'll send it out to you ASAP.
 
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Lawnboy77

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The part numbers for the washer and bearing are:

Thrust bearing 252-76
Washer 252-80

You can Look up these parts by punching in the latest version of just about any F series produced after 1996. To get those numbers I looked it up by way of a 1996 model 10401.
 

Teds

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Have you tried adjusting it? The manual doesn't really talk about using shims, but they do mention a certain amount of clearance. The recoil shaft is splined and needs to be set just so, basically. They are pretty simple arrangement. If you choose to remove it, follow the manual instructions. A third hand is helpful for this procedure.

The LawnBoy manual for these mowers and many others is available for free download, maintained very helpfully by Toro.
 

modernclassic

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Have you tried adjusting it? The manual doesn't really talk about using shims, but they do mention a certain amount of clearance. The recoil shaft is splined and needs to be set just so, basically. They are pretty simple arrangement. If you choose to remove it, follow the manual instructions. A third hand is helpful for this procedure.

The LawnBoy manual for these mowers and many others is available for free download, maintained very helpfully by Toro.

No, I was not aware that it could be adjusted. I've got the manual, I'll go through it again.

E: I just looked over the starter section for the D600s. I'll give it a whirl trying to reposition or reseat the mechanism tomorrow.
 
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modernclassic

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The part numbers for the washer and bearing are:

Thrust bearing 252-76
Washer 252-80

You can Look up these parts by punching in the latest version of just about any F series produced after 1996. To get those numbers I looked it up by way of a 1996 model 10401.

Do I need to take the mower apart to verify this "slop" or play in the bearing? I pushed up on the blade from the bottom and there is no play ie the flywheel didn't move more than a cat hair.
 
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