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I have an MTD Yard Machines Tractor, series 607/608/609 (I forget the exact model number) but it has a 46" PTO deck that is engaged and disengaged with the PTO arm, to start the cutting blades.

The problem is that the belt is always a little loose. I've bought different brands of belts over the years and some are so loose that the tractor won't even begin to cut unless I pull on the PTO arm about halfway to apply more tension to the belt. There are other belts I've bought that do ok, but the belt does once again slip in heavy grass, so pulling the PTO arm helps.

I tried belt dressing, but the belt got so sticky that it wobbled and eventually fell off the pulleys.

Is there some sort of tension adjustment, so I can prevent these belts from slipping?
 

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I have an MTD Yard Machines Tractor, series 607/608/609 (I forget the exact model number) but it has a 46" PTO deck that is engaged and disengaged with the PTO arm, to start the cutting blades.

The problem is that the belt is always a little loose. I've bought different brands of belts over the years and some are so loose that the tractor won't even begin to cut unless I pull on the PTO arm about halfway to apply more tension to the belt. There are other belts I've bought that do ok, but the belt does once again slip in heavy grass, so pulling the PTO arm helps.

I tried belt dressing, but the belt got so sticky that it wobbled and eventually fell off the pulleys.

Is there some sort of tension adjustment, so I can prevent these belts from slipping?

I have a similar problem right now with my Troy-Built Super Bronco 21 hp 42" pto engaged deck. The PTO drive belt when engaged is loose (almost loose enough when engaged that I could remove it) anyway the only to get the blades to start moving is to put the deck on the highest position which gets them going then lower the deck maybe 2 levels if I'm not cutting much grass, any lower and the slow down and stop.

I've contacted Troy-Built and they said that maybe the deck isn't level causing the belt to be loose, I've check this and the deck is level. Non of the pully's attached to this belt seem to be adjustable. So I'm really stuck to what I can do besides bring it to a tractor mechanic, which I would rather not pay for.

Any suggestions would be great.
 

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There's one cheap option that could work for you, but YMMV. Belts come in almost all sizes, in 1" increments. Find the exact width and length of your 'recommended' belt, then buy the one that is 1" shorter. I did this and the belt was not coming off at all.
 

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There's one cheap option that could work for you, but YMMV. Belts come in almost all sizes, in 1" increments. Find the exact width and length of your 'recommended' belt, then buy the one that is 1" shorter. I did this and the belt was not coming off at all.
I did that and the deck would not disengage.
 

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Discussion Starter #5
I did that and the deck would not disengage.
problem solved :ROF

seriously, this did the same thing for mine too. This means that the pulleys have loosened enough that the normal belt won't catch, but less than a full 1".

In my case it was better to have the PTO on all the time, let the belt loosen up, rather than the original length. At least it's working...so well, it won't ever stop cutting.

Extremely surprising though, that they don't have a belt adjustment, since it seems common that the springs would loosen over time and (as we've demonstrated) even a slight variation causes problems.
 

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I joined this site because I have the same problem and thought I might find some help here. Oh well. I thought of the shorter belt solution a long time ago but I'm afraid to do it because of safety issues. Maybe I just don't have a choice if I want to keep using this thing. Mine is a 608 I bought new in 2000. I suppose I shouldn't complain too much. It's been a good machine without many problems other than belts and blades and batteries.

I will continue to monitor this thread in the off chance someone else comes up with a better solution. Meanwhile, happy mowing all.
 

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I guess they got worse as they got newer. My 1991 669 has a rod that goes to the front deck mount thats adjustable. It also has a spring that goes from the back deck mount to the rear of the tractor.

If you have the rear spring just make an adapter to make it mount a 1/2 inch farther to the rear.

Walter
 

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Could it be you have a 1/2" wide v-belt and should be using a 5/8" wide one?..

I have substituted a 5/8" belt on some tractors with success I had, that had pulley sheaves wide enough to accept one,but didn't call for one originally,when I had problems with the 1/2" belt slipping or being so "loose" while disengaged the belt would often flop off the deck drive pulley..

Some idler pulleys have slots for adjusting the pulley in or out to change belt tension...or you might be able to increase the tension on the spring..

Sometimes the deck moves around so much on loose or worn out
mounting points it changes the distance between the engine and deck drive pulley too--any "slop" there is going to adversly affect belt tension and alignment..
 

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FIXED THIS PROBLEM:

The MTD belts I have been buying for years are 5/8 X 66 1/2. I bought a 'Thermoid' Power Plus 5H660 belt which is 1/2 inch shorter. It works great and was only twenty bucks from the local Western Auto store that is high as ****.
(The OE MTD belt was $35.00 at the same place) My wife (who does the grass cutting :) is out there right now and she's is happy camper.

The Power Plus belt is Kevlar Cord Construction and sure passes the eye test. I'm going to be very surprised if I have this problem again anytime soon.

Just for the heck of it I googled up the belt on line. It is $18.55 plus S&H no doubt.

http://www.mowerpartsweb.com/Iteminfo.asp?ITEM=TB5H660

I also replaced the deck belt while I was at it with the same brand belt. If I have no more problems this year I will replace all four belts next spring before I start cutting.

Good luck to you all.

Ray
 

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you might try finding a tighter idler tension spring
 

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Ray I'm running Thermoid belts on my Craftsman. Great belt, best part is it's USA made. I get mine from the local Western Auto also.
Walter
 

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Other Things To Keep Inmind. Is Theres Room For A Biger Idler Pully? That Would Definatly "shorten" The Belt So To Say.
Is A Shorter Or Stifer Spring A Possibility. These Have Helped Me In The Past On Neibor Prodjects. Just Remember That Changing The Main Pully Sizes Change Speed Of Attactment.
 

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Old thread I know, but I have a somewhat similar problem with an MTD 46" deck.

Are any of you kinda/sorta/maybe looking at this thread? or should i start a new one?
 
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