is occasionally...sticking is the best word for it, i guess. twice now i've noticed my idle sounded ever so slightly off, popped the hood, and could see the tensioner pulley catch and stop moving in sync with the "off" feel i was getting. then it would be fine again; then a week of running beautifully. yesterday she did it again.

so, given how my vac pump behaved right before it blew, i suspect she's telling me i need a new tensioner pulley. anything else worth checking before i replace it?

 

I found this thread from our forum... https://www.ford-trucks.com/forums/7...tensioner.html

it should be helpful. Especially the part about off-idle and a suspected alternator, and removing the belt and spinning the all the pulleys by hand, and how one of the posts specifically mentioned when they spun the tensioner by hand they heard an odd sound...

The Bronco/F250 manual spells it out it just takes more time to read that.
1996 Bronco/F-Series Workshop Manual

..." 3. If any of the accessories are damaged, or have a worn or damaged bearing or internal torsional resistance above normal for any reason. All of the accessories should be rotatable by hand in the unloaded condition. If any are not, the accessories should be inspected.

 

Goodyear part numbers.

49037 A/C Drive Belt Idler Pulley

49008 A/C Drive Belt Idler Pulley Tensioner Pulley

49219 Belt Tensioner Assembly

 

just had to replace tensioner and idler pulley, second Idler pulley so far, from what I gather it's a common problem

 

Do you have the old tensioner or the OBS upgrade.

It's worth looking to the upgrade tensioner if you're replacing it. The original owner of my truck did it so I don't know how involved it is but I do know it helps with keeping the belt running tight.

 

Bearings in the idler pulleys do tend to wear out. I have been through a couple of them (all have been replaced now). When they go and toss a belt, it gets expensive to replace both the idler and the belt not to mention also getting stranded. When I have the belt off for any reason or once a year, I check the idlers to make sure the bearings are ok. Replace when questionable (around $30+ at Napa). When I haul a trailer cross country, I always keep a spare belt, idler pulley, gpr and cps with me. These things are the items that tend to go out the most frequently and leave you stranded. The belt may not frequently wear out, but if an Idler goes or vacuum pump the belt usually gets toasted too.

 

what upgrade? Just went to the dealer and got both the new tensioner and a new idler pulley. Didn't know anything about an upgrade

 

I'd like to know what upgrade is available, too. How do you tell if you have an "old" one or the "upgrade" one?

 

If you have one tensioner pulley, you have the OBS tensioner. If there are two you have a superdoody tensioner.

I think you can just bolt the newer one in and put a longer belt on it. Someone who has done it would have to verify that though.

There are several advantages. The tension range is greater since it wraps the belt around two moving pulleys instead of one. There isn't a out of balance force that causes the tensioner to bend. This reduces the chance of the tensioner running out of true. The chances of breaking a tensioner bolt is less.

 

Do you have a pic that you could post? Is a longer belt needed?

 

ha! superdoody! that's great

 

Here is a pic from NAPA of the SD tensioner.



There are two listed lengths of belts for our trucks at most part houses. The short one is the stock tensioner, and the longer one is for the SD tensioner.

Ford did this as a mod under warranty for people with belt problems.

 

Is there really a big issue with the belt not being tight enough with the stock setup? This superduty ungrade sparks my interest, but I can't say I've ever had issues with the original setup.

 

Just fix it before I get there, So I'm not stuck helping you do it. =)

 

Great info, thanks!