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I recently acquired a new (to me) Troy Bilt 14AT809H766 with the Briggs & Stratton 752B0344E1 21HP engine.

I has right under 300 hours on it. I just installed all new filters and changed the oil.

Anyways, about 3/4 into cutting our 2 acres I could smell burnt rubber and a bit of black smoke (from the belt) came from the front left area of the mower. After that it stopped moving.
I could hear something spinning when I press the throttle pedal but, no movement.

I'm assuming a belt has gone out but, I honestly don't know where to start.

All belts seemed to be intact but, I'm pretty sure they were all loose -again, I didn't know where to even start.

Any ideas what to look for?

Thanks in advance for any help!

I found the MTD part numbers for the belts -I would go ahead and replace all four.

Is there a service manual or something else that will give me step-by-step instructions on changing all belts?

Not so much a step by step but start with the parts book then download the service manual
http://www.mymowerparts.com/pdf/
Scroll down to the Troy Built section then parts manuals , find your model & download it.
If you have troubles, use this as a refference so we can tell you to remove the two pulleys No 35 in order to remove belt 32 ( thats a hint ).
From the same site you will find the troy built service manuals.
Then go up a bit and look at the MTD manuals because MTD made your mower.
The "Must Have book 2 " is the one relevant to your mower and more detailed than the single model service book.

You will have to make yourself a spring hook as MTD love springs.

I will add one thing. Take lots of pictures before you take anything apart. Lots of people ask where the spring connect after they try to put it back together.

Thanks for all the advice, guys. Seems like this is going to be a weekend project. Yay...

Good heads up on taking pics.

Spring hook?

If it is any help, this is how I do it.
Remove battery & drain fuel tank
Remove the battery case and remove the upper belt through the battery case hole.
On some you have to either drop the right side of the tranny or remove the tranny pulley to get the belt out.
Remove the deck
stand the mower up on it's bum ( why I drain the tank )
Remove springs pulleys & lower belt
In this position the mower in right in front of your face and you can see clearly where everything goes.
You also don't get to eat dirt every time you move something.
Check all of the pulleys carefully.
If they have any damage on the working surface or are rough or noisy when you spin them, replace the pulleys.
A worn or damaged pulley can destroy a brand new belt the first time you mow

http://www.troybilt.com/webapp/wcs/...langId=-1&logoCode=02&modelNumber=14at809h766

see operators manual for parts list

just remove deck & replace all idlers & belts, you should be good to go

bertsmobile1 said:

If it is any help, this is how I do it.

Click to expand...

That sounds pretty straightforward I guess haha
Sounds like a one or two day job. May call a buddy over for bro time. Mainly I'm just plain lazy LoL

I'm showing my mower to have 4 belts -not 3..? The part search on the Troy-Bilt website for "belt" comes up with 4 P#'s. Haven't check the parts diagram yet. Lame, I know.

Also, should I worry about losing motor oil while it's on its ***-end? I just changed it hahaha

mechanic mark said:

http://www.troybilt.com/webapp/wcs/...langId=-1&logoCode=02&modelNumber=14at809h766

see operators manual for parts list

Click to expand...

I downloaded and printed off all 3 of those the other week. I was just hoping for better instructions. I'm used to having it all explained step-by-step with pictures. I have "specialized" in parts (automotive and appliance) since 2005-ish and have professionally worked on cars (still ASE certified in 2 areas until mid-2017) and am currently professionally working on appliances so, I guess I'm spoiled when it comes to having proper documentation.

That but, MOSTLY because I've never really worked on one of these and I don't want to have it spread all out outside for weeks for the neighbors to see. It's embarrassing. No shame in my game for admitting that haha

There are 2 drive belts as this mower uses a sliding sheeve to vary the speed.
Same as the new constantly variable drives being found in modern cars.
If you take off the input shaft pulley you will need a rattle gun which I am sure you have.
When tightening it be careful as they shaft is not be best design and will fracture if torqued too high.
The other belts are a deck belt and a PTO belt to the deck.

bertsmobile1 said:

There are 2 drive belts as this mower uses a sliding sheeve to vary the speed.
Same as the new constantly variable drives being found in modern cars.
If you take off the input shaft pulley you will need a rattle gun which I am sure you have.
When tightening it be careful as they shaft is not be best design and will fracture if torqued too high.
The other belts are a deck belt and a PTO belt to the deck.

Click to expand...

Thanks for the clarification on the belts. I do not have an impact gun at this time. It's on my list of needed (more expensive) tools.

So should both drive belts be tight? Anything I need to look out for other than worn pulleys?

I'm just going through possible scenarios before tearing into this thing. Wanna be prepared because I'm sure I'll find something broken or out of spec that I'll have to order -essentially slowing me down.

Bent idler pulley brackets. And remember to take lots of pictures before and durring tear down. Especially where the springs connect. They are a huge pain to find where they go after the fact. I had a friend who could not remember how to get out of a paper bag to save his life. I had him paint each connection point for the springs. One color for each spring. Paint on the spring and connecting point. It worked very well for him. He forgot about the springs and when I showed up it was a lot easier to figure out the problem.

When you apply the parking brake the front belt goes a little loose but not much because these mowers have a N position on the axle gears so do not need to allow the belts to slip in order to stop the mower.
The front pulls against the back to change the speeds.
Check that the sliding sheeve on the common pulley can move up & down smoothly , if not the entire pulley will need replacing. ( not cheap )
Other than that as per the previous poster.
Pull it down Friday arvo so you can go to the parts store Saturday morning.
I can almost garantee t least one of the idler pulleys will be toast.
Look closely at the spring mounting points the springs cut them out so they oft need a quick blob of weld.

Thanks for all of the advice. I'm not sure when I'll get around to it but, I'll be sure to update here with what I do/find.