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Posted: 10/9/2005 9:19:35 AM EDT
I have a less than 1 freaking year old Craftsman mower with a 7 hp Briggs and Stratton engine on it. Well a couple of weeks ago I hit a root and bent the hell out of my blade. I went and got a new blade but found that the blade key adapter had been damaged. The key part that fits into the slot on the shaft had sheared.

No problem, I thought and ordered a new one. Well I get it installed today and go to fire her up and the thing shakes and shutters like a mother and shears the new adapter as well!

Bent shaft, right?

My question is, is it possible or cost effective to have a small engine's shaft replaced or would I be better served to replace the mower altogether?

I hate it because I doubt the thing is even fully paid for as I dumped it on a CC with a little bit of a balance.

Thanks from one pissed of, tall grass having, cross looks from neighbors getting SOB!
Link Posted: 10/9/2005 9:32:54 AM EDT
The good news is that its a B&S motor, very very common. The bad news is that the output shaft your talking about is probably the end of the crank shaft = direct connection. I'd fire it up without a blade on it and listen for knocking (half engine speed will be journal bearing). Hopefully no knocking. I've heard that a crankshaft can be re-balanced by welding on weights (to make up for the slight bend), but it will have to be removed from the block. sorry not much help.
Link Posted: 10/9/2005 9:34:15 AM EDT
First off check to see what card you used. many off them extend and insure stuff bought with the card. I bought tool chest with my amex card and when I was putting it together it dropped and crushed the lid. Called up Amex and they took infao and in 3 days gave me back credit for it.

I'm in the same boat when it comes to small engines. I have a chipper that need a engine. The engines that fit it cost 3-4 hundred and the chipper it only worth 150-2.


On yours I would just get a new mower. Get Honda this time. a 7hp is goingto cost 2-3 hundred.
Link Posted: 10/9/2005 9:35:30 AM EDT
If you are not used to working on small engines, it is more cost efficient to get another engine.  Look to Northern Tool (used to be northern hydrolics) for the best engine prices.  Real farm supply stores have engines cheap as well.

I have overhauled engines such as yours, and it is not too difficult.  A new crank shaft and some gaskets are probably in order, but tear into it first to detirmine the damage.
Link Posted: 10/9/2005 9:41:05 AM EDT
[Last Edit: 10/9/2005 9:42:01 AM EDT by FiveO]
It won't crank at all with out the blade on... It is like it has no compression and won't fire.

I reread my forst post. To be clear the engine never really ran with the new key adapter and blade on it, it fired up but knocked and shook hard and quit, shearing the new key adapter.

No way I can fix it myself so I'd bet the cost of having it done would be too much compared to rplacing it...

Sucks bad. I kinda splurged and got a high wheel, self propelled one... First time I'd sprung for a good un!
Link Posted: 10/9/2005 9:41:10 AM EDT
Take the blade off and the sparkplug out. Prop the mower up to a position that lets you have access to the shaft and stabilize the mower. Have someone pull the starter rope while you hold a piece of chalk or marker close to the shaft.  You might have to reposition your marker a few times to get close enough.  If the marker leaves a solid, uninterupted line around the shaft then it isn't bent.  If the marker only touches the shaft in one small area per revolution then the shaft is indeed bent.

Look on the Tulsa Engine Warehouse for a new motor or price a new shaft from a local parts supplier.  If you can disassemble and reassemble an AR, you can work on a B&S engine.

Good luck.
Link Posted: 10/9/2005 9:42:33 AM EDT
Best way to fix  Running it with a bent crank is very unsafe.
Link Posted: 10/9/2005 9:42:44 AM EDT
It will cost as much or more to fix it as a new one will cost.

Link Posted: 10/9/2005 9:43:18 AM EDT

Originally Posted By Pangea:
Take the blade off and the sparkplug out. Prop the mower up to a position that lets you have access to the shaft and stabilize the mower. Have someone pull the starter rope while you hold a piece of chalk or marker close to the shaft.  You might have to reposition your marker a few times to get close enough.  If the marker leaves a solid, uninterupted line around the shaft then it isn't bent.  If the marker only touches the shaft in one small area per revolution then the shaft is indeed bent.

Look on the Tulsa Engine Warehouse for a new motor or price a new shaft from a local parts supplier.  If you can disassemble and reassemble an AR, you can work on a B&S engine.

Good luck.



Cool. Gonna try that!

Thanks!
Link Posted: 10/9/2005 9:45:52 AM EDT
Another thing.  You might have partially sheared the timing key on the flywheel.  If so it will run shitty if at all. A fully sheared flywheel key wont let the engine start most of the time.
Link Posted: 10/9/2005 9:47:22 AM EDT
check ebay for a motor or type in model number for the eng in google or some type of search engine.
i found a riding mower engine same manf.  specs and everything for about half what i could buy it locally.
Link Posted: 10/9/2005 9:53:51 AM EDT
Have you tried Tannerite?
Link Posted: 10/9/2005 5:40:14 PM EDT
Many small engine shops can indeed straighten out a bent crank at a fraction of the price, provided it isn't a very bad bend. There is a jig that most places have, I'd call around and get an esimate.
Link Posted: 10/9/2005 6:15:19 PM EDT

Originally Posted By jstang:
Many small engine shops can indeed straighten out a bent crank at a fraction of the price, provided it isn't a very bad bend. There is a jig that most places have, I'd call around and get an esimate.



Cool! Thanks I'll try a couple of places tomorrow!



Originally Posted By hanau:
check ebay for a motor or type in model number for the eng in google or some type of search engine.
i found a riding mower engine same manf.  specs and everything for about half what i could buy it locally.



And if that does not work I just found a replacement engine for $85!

Thanks all.
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