How JustAnswer Works:
  • Ask an Expert
    Experts are full of valuable knowledge and are ready to help with any question. Credentials confirmed by a Fortune 500 verification firm.
  • Get a Professional Answer
    Via email, text message, or notification as you wait on our site. Ask follow up questions if you need to.
  • 100% Satisfaction Guarantee
    Rate the answer you receive.
Ask JON Your Own Question
JON, Small Engine Technician
Category: Small Engine
Satisfied Customers: 1338
Experience:  Certified Small Engine Technician
Type Your Small Engine Question Here...
JON is online now
A new question is answered every 9 seconds

I have a 12.5 40 inch 40507x8c. I bought a 40 inch belt on

Customer Question

I have a 12.5 40 inch 40507x8c. I bought a 40 inch belt on line and it is too loose. I cannot find a manual on-line.
Submitted: 1 year ago.
Category: Small Engine
Expert:  Vince O. replied 1 year ago.

Hello, are you changing the blade belt? I found a parts manual and site.

Customer: replied 1 year ago.
the blade belt. I found a dozen parts diagrams. My question was about the belt not fitting. Way too loose. I bought a belt for a 40" Murray. It's says 40 inch on the tractor. Parts manuals are easy to find, but cannot find a service manual. But again, I was looking for advice on why the belt does not fit...meaning, it is too loose.
Expert:  Vince O. replied 1 year ago.

The belt may not be routed properly. Does the deck in the parts view the same as the deck on the tractor?

Customer: replied 1 year ago.
It is routed properly. Exactly as the parts drawings show. When I was first looking for a replacement belt, I found a web site that showed two different length belts for the model number. I cannot find that website again. That now leads me to believe, that maybe there is something unique with this model. I am very mechanically capable so, it was detailed knowledge of this particular Murray model I am hoping for. I cannot tell from the drawings and, cannot find any service manual, that describes any belt tightening adjustment other than the three hole options in the engagement lever.
Expert:  Vince O. replied 1 year ago.

I couldn't find a service manual and can't do anymore so I am opting out.

Expert:  JON replied 1 year ago.

The proper belt size is 1/2" X 86" What belt did you purchase?

Expert:  JON replied 1 year ago.

Is the idler pulley working like it should. It will move and spring back under pressure.

Customer: replied 1 year ago.
Hi Jon. Long drive today. Will answer tonight. Thanks.
Expert:  JON replied 1 year ago.

Not a problem. Have a Happy 4th.

Customer: replied 1 year ago.
The lever that engages idler pulley appears to move properly. I have moved the spring to the last hole in the arm, which applies the most tension but it still is very loose. The belt I bought is labeled Murray 40" and is 037x62MA....and it says it is 86 inches. I am 99% sure routing is correct as it is pretty simple design and the drawings on line are pretty easy to understand, for that part at least. What I cannot really tell from the drawings, is if there is another major adjustment that may have loosened up. Can't find a manual ! The tractor is at my cabin.....I won't get back there for a few weeks now.I bought it at an estate sale and since the belt was loose, I thought all I needed was a new belt. Well, the belt I took off it actually looked like it was new, so, previous owner apparently had same issue and gave up. Go figure ! :- )I did find one web site that showed two different length belts for that model..... Am trying to find that website again. NO NEED TO ANSWER TONIGHT. it is late and a holiday
Expert:  JON replied 1 year ago.

That is the correct belt for that model mower. I will include another Deck Diagram. I am beginning to wonder if someone may have installed the wrong pulleys on the machine at some time. Do any of the pulleys look newer? I have seen people install wrong pulleys and then a new bel will not work due to change in pulley size.

Customer: replied 1 year ago.
I have to wait until I get back to the cabin and look. Will "just answer" harass us if we leave this open until I return? I finally found a good high quality PDF of parts manual but can find nothing that is a service manual.
Expert:  JON replied 1 year ago.

Not sure how they do this. I have only been on here approx. 3 weeks. I uploaded a Parts Manual from Murray for you. It is pretty clear to see. I will see what I can do about a Service Manual for you.