Okay, I had taken in my truck to a mechanic and he had replaced my belts among other things. He was unable to find a replacement for the belt that ties in the smog/air pump and the fan so he replaced it with a similar belt and twisted it to tighten it up. This wore out the belt faster than usual and gives a squeaking noise. Unfortunately my mechanic retired and moved away, so I'm attempting to replace the belts myself to keep costs down.

I'm unable to find a belt size between the water pump/fan to the smog air pump. I am pretty firm on installing a belt as I have seen many posts about removing the smog/air pump altogether.

I've attached a couple of pics if that helps. I really appreciate anyone's help with this, thank you!








1981 Ford F-150 4.9L 300 L6 Engine
1981 Ford F-150 Custom 4.9L 300 L6

 

Hello jcryuu, and welcome to the forums.

When I had to find a belt with an unknown size, I just asked for a parts store guy who would bear with me as I tried a number of them out in the parking lot. Loosen the smog pump so it freely moves and then just go through belts until you find one where you can swing out the smog pump at least enough to put some tension on the belt.

I think I had to go through 5 or 6 and just had to say, "nope, longer" or "nope, shorter".

Then, write the length down once you have it.

 

I have seen people take a small diameter rope and loop it around the two pulleys, marking it and then measuring the length. This will help with the initial trial.

 

Thanks 1986F150six - Taking your advice, I used a string for an inner diameter measurement, and a fabric tape measure for the outer diameter. I ordered accordingly...hopefully that works

Thanks for the advice!

 

Glad to be of help! For the air pump, the v-belt is usually less wide than the other belts. Did you notice that?

 

I did, thank you! The measurement I took was 3/8 of an inch. So I ordered Gates 7381, and hopefully that will solve it :-) Thanks again