# Wheels not turning under load -post predator engine swap



## mntbiker2008 (Mar 22, 2018)

Hey all,

I just did the predator engine swap on my old MTD 22" blower and am stumped here. Hoping someone can point me in the right direction. 

I just swapped out my old worn out Tecumseh engine for a new predator 6.5 hp engine. I copied the swap off a video I saw on youtube.

Pulleys came from electric motor warehouse:
2ak27x3/4 and ak20x3/4

I also am using a 29" belt for the drive line.

I have not yet flipped the transmission but am ok with only having the 2 forward speeds. I never went over 2 while moving snow anyways.

The issue I'm having is, the blower moves ok until it is under a load (like going up an elevation or bump.) I've tried changing the spring out on the belt tensioner and have gotten the cable as tight as it will go.

Any ideas what could be going on? 

Thanks!


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## leonz (Dec 12, 2014)

Have you looked at the rubber drive tire? it sounds as if its worn down and cannot maintain contact pressure.


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## RedOctobyr (Mar 2, 2014)

Welcome to the forum! 



Can you see what's slipping? My guess would be that the belt is too loose for some reason. You could maybe remove the belt cover, and put the nose the machine up against something solid. Then engage the drive handle, and watch the pulleys to see if either drive pulley (at the engine, or the other end) stops turning. 



If the non-engine pulley stops turning, then you have a loose belt. And if the pulley at the engine stops turning, then the pulley is not staying locked to the shaft, for some reason.


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## mntbiker2008 (Mar 22, 2018)

leonz said:


> Have you looked at the rubber drive tire? it sounds as if its worn down and cannot maintain contact pressure.


Thanks for the quick replies! I have checked that. It's worn but still in decent shape. I looked under the belly while the machine was against a wall and driveline was engaged. It appeared to be in contact with the friction plate. 



RedOctobyr said:


> Welcome to the forum!
> 
> 
> 
> ...


Thank you for that! As I mentioned above when it was against a wall, I did notice that the belt stop turning. The main pulley on the engine was still spinning but belt stayed in the same place (actually started to smell). The belt seems tight but maybe I will try a 28" belt instead and see if that works. I'm trying to attach a photo of what I'm working with but having trouble.


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## mntbiker2008 (Mar 22, 2018)

Think I should downsize the auger belt as well? Or could I put some washers under the engine to bring it up a little bit so I don't have to replace belts again?


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## leonz (Dec 12, 2014)

If you wrap your hand around one or both belts and rub it up and down and you have rubber flecks in the palm of your hand the V belts are toast.

If your happy with the condition of the rubber drive disc- I am not as that thing should have kept on trying to dig into the wall I would replace anyway.

Chances are the V belts have stretched over time from the amount of use they received PLUS thier age as the ozone in the air will degrade the V belts.

I would rather see you replace the drive disc and the two V belts with Kevlar V belts of the same size as your snow mule should be trying to run into the wall and trying to eat it if the rubber drive disc is in good shape too. you have to remember that the rubber drive tire will degrade over time as well with age.

I am not trying to spend your money, but you need a snow mule that will be able to clear off the END OF DRIVEWAY MONSTER with few if any issues.


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## Kiss4aFrog (Nov 3, 2013)

Are you sure the small pulley on the engines crankshaft for the wheel drive is the same size as the one removed ?? Might just be the photo but it sure looks small. If it's too small the belt doesn't have enough surface area to get a grip.

.


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## RedOctobyr (Mar 2, 2014)

The belts do look quite loose. When you squeeze the drive handle, does that tighten up on the drive belt, or does it move the rubber wheel in contact with the aluminum disk? If the rubber wheel moves to the disk, and the belt tightness doesn't change, then it looks loose to me. 



Raising the motor might be a way to improve both belts without needing to buy new ones.


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## Motor City (Jan 6, 2014)

I've done a few of these swaps on Craftsman versions of MTD's and have been able to use the original pulleys and belts. You may want to re-think trying them.


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## mntbiker2008 (Mar 22, 2018)

leonz said:


> If you wrap your hand around one or both belts and rub it up and down and you have rubber flecks in the palm of your hand the V belts are toast.
> 
> If your happy with the condition of the rubber drive disc- I am not as that thing should have kept on trying to dig into the wall I would replace anyway.
> 
> ...


Thabk you! Both belts are actually brand new (only a month old). I will look at replacing the rubber disc as well. It wouldn't be a bad idea. 



Kiss4aFrog said:


> Are you sure the small pulley on the engines crankshaft for the wheel drive is the same size as the one removed ?? Might just be the photo but it sure looks small. If it's too small the belt doesn't have enough surface area to get a grip.
> 
> .


It is pretty close to the same size as the old one. Unfortunately I already got rid of the old blown up motor (kicking myself for it now) so there's reslly no way to tell for sure. The old motor was a dual shaft and had a very small drivetrain pulley. 



RedOctobyr said:


> The belts do look quite loose. When you squeeze the drive handle, does that tighten up on the drive belt, or does it move the rubber wheel in contact with the aluminum disk? If the rubber wheel moves to the disk, and the belt tightness doesn't change, then it looks loose to me.
> 
> 
> 
> Raising the motor might be a way to improve both belts without needing to buy new ones.


The rubber disc does come in contact with the plate. It will propel itself across the shop floor no problem. It's just when it comes to something where it puts strain on the driveline... That's when it stops. 


I haven't had a chance to get back out there yet but I'm going to try to work on it tonight and raise the engine a bit to take some slack out of the belts and see if that helps. I'll post back with the results. Thank you for all the help!


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## Toro-8-2-4 (Dec 28, 2013)

When you compare the AK style industrial pulleys to the typical snow blower pulley you can not go by outside diameter. You need to compare pitch diameter to pitch diameter (PD). This diameter is where the belt actually sits in the V groove. You clearly need more belt tension. . You have a two shaft machine so you want to slow the tractor drive down by about 50%. You need to use the PD to calculate your speed change. If you are ok with the speed I would get a shorter belt or change the tensioner configuration. I have been through this on my Peditor swap. I ended up changing the tensioner by making my own, used a shorter belt and used a different pulley. Part of the challenge was to slow down the speed and use a pulley size that could still fit under the belt cover. I wrote about it here in several posts where many others also contributed their experiences. I would take a search on this site and see what else you can learn to help you get to a good reliable set up. Nothing wrong with Youtube also but you want to find someone who has your set up. Not all MTD's are exactly the same. You can do it.

Good Luck!


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