I recently had to replace the belt tensioner (again). I noticed I had to pull it to it's limit to get the belt on. I suspect I may have too short a belt for several reasons. I have broken 3 tensioners in 15 years, it is very difficult to get the belt on, and after looking up the belt, it recommends a different one than what I have. I am now running a Gates KO61115. The Gates web site recommends KO61110 (w/o Leece Neville Alt) and KO61130 with Leece Neville alt. I'm not sure which alternator I have but I'm sure the KO61110 is way too short and I suspect the KO61130 will be too long. Even though the KO61115 does fit, I suspect it is the cause of the tensioner problem (I don't think it is riding in the proper range of operation).
Any help with this problem is greatly appreciated.
Tom

 

I just did my belt. w/o leece alt the belt lenght is 111 5/8" long. with leece alt it is 113 5/8" long (If i remember right, I do know it is longer). Leece alt runs a larger diameter pulley i do believe. my alt pulley is 2 3/4".

 

I don't have the serp belt on my pickup, but in general the part numbers for belts don't necessarily reflect the length. 110, 115, and 130 /could/ be sequentially sized, but I doubt it. It's just a manufacturer part reference.

SO, the best thing to do is get the belt length of each part # and see what you come up with. If the 110 is a couple inches longer than the 115 then boom, problem solved. If it's way off or shorter then you're in the market for something else.

I'm pretty sure that alt is for the ambulance package. You should have the 1G alt if you don't have the ambulance package.

 

You need to get that tensioner in the middle range or you'll be breaking it off in short time.

I had a problem finding a belt for my truck too as I deleted the vac pump and tried several shorter different belts just to come and find out the factory belt was the right length even though I have one less piece in there.

After market idlers and tensioners don't always come with the same size pullies on them as factory, try a belt that's half inch longer and you should be good, don't worry about the different alternators.

 

I had the exact same problem a month ago. Ford, Autozone, Adavance Auto, and Carquest all show a 111 5/8" X 13/16". Dayco # 5061115 or Ford F4TZ-8620-T. The Ford dealer told me the OEM belt used to be longer but got superceded to a shorter part #. Ends up only NAPA had the longer belt that measures 112 1/2" X 13/16" Gates belt - under NAPA # NEH 25-061120