# MTD lawnflite 12.5 / 38” cutting deck belt tension



## olriley (Sep 17, 2017)

Hello, I’m having a little trouble with this little tractor again.I had to change the deck belt. The new one feels too slack and the deck is not cutting properly. The belt flaps around and doesn’t make that nice positive 'helicopter' engaging sound then I lower the deck like it used to. 

I went for this one off eBay, because it said 667 in the title, and the full SN matches in the list in the ad... mine is 137-667-611/F307C. Anyway, it’s 69” x 1/2”
https://rover.ebay.com/rover/0/0/0?mpre=https://www.ebay.co.uk/ulk/itm/200814447967

I couldn’t measure the old belt for comparison (explanation below).

The new belt is cotton covered whereas the old one was rubber. I am sure it was tighter than this. I don’t see any means of adjusting tension so I’m confused! See how much I can deflect it, that’s with the deck at its lowest setting. Maybe I put the deck back together wrong?

Another thought: The V-profile appears to be a little narrower than the old one. Maybe the pulley is worn and this new belt is riding deeper in the groove, not getting enough tension.

*I paid someone to mow the lawn, the grass had got a bit long, he managed to clog up the outlet and then foul the blades themselves. He said it started to smoke, then something went bang  ... belt was vapourised but not before pulling one of the keeper pins into the drive pulley. I had to remove the metal plate holding the keeper pins, bend it all back into shape, and remove straighten out the pulley (the 'dumbbell' type with double pulley) which had some big dings. It runs okay but I might have to replace it.

Thanks in advance for your help! Oliver


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## olriley (Sep 17, 2017)

Can anyone please help me identify the proper replacement deck belt? Thanks


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## olriley (Sep 17, 2017)

Ok it’s 754-0329A
I’ve ordered one from a different source, let’s see if it fits. (The other I tried did not carry this reference -although claimed it fit)


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## TecumsehBriggs (Jun 17, 2011)

A lot of aftermarket belts, especially ones made overseas, are not the correct length. As long as you know the proper length, you can measure a new one at the store before buying. I go to Farm & Fleet & measure before I buy. Don't buy a 1/2"x96" belt if it measures 1/2"x95 1/2". It makes a difference. Don't let the "experts" at the store tell you differently. They're trying to pull the "nominal dimension" lumber scam, but with belts. Doesn't work every time, but will work some times.

Sent from my SAMSUNG-SM-G850A using Tractor Forum mobile app


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## FredM (Nov 18, 2015)

doesn't the deck have a belt tensioner adjustment threaded link?.


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## olriley (Sep 17, 2017)

FredM said:


> doesn't the deck have a belt tensioner adjustment threaded link?.


I dunno .... where would I find that? Useful if so but I couldn’t see anything obvious


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## bOB dAVIS (Jan 7, 2019)

Hi Olriley, Could you do me a favor? I just posted today about identifing an older mtd I just bought that has been painted over and has no serial plates left on it . Mine is a 12.5 horse flat head briggs with 38 cut .The shifter for forward neutral and reverse is between my legs on a removable plate and the speed shifter is on the right side of the same removable plate . Could you take some pics of your mower so I can determine what year mine is and the serial #s for parts . It sounds like mine is very similar to your mower . Thanks for any help . I'm Bob.


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## pogobill (Jan 31, 2012)

olriley said:


> I dunno .... where would I find that? Useful if so but I couldn’t see anything obvious


I looked hard at your tractor, and I can't see any place where they may have been a belt tensioner!?! There should be.


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## FredM (Nov 18, 2015)

on your first photo there are 2 links with a slight "S" shape, drop these down to the lower holes in the tensioning link behind the front axle, in the 4th photo to the left of your hand and slightly above, you will see the links I mentioned, that will push the deck back against the belt.


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