'95 F250 ECLB 4x4 5-speed, 69,000-ish miles (really!). Mostly stock. Mostly unknown service history.

Just doing my usual pre-trip systems check, lights, fluids, etc, I happen to notice the belt takes a funny angle coming off the passenger-side idler. All the pulleys seem to line up, but then I notice the tensioner pulley is actually angled a bit. So I wind up the spring to de-tension the belt and slip it off, and everything "straightens out". When I swing the tensioner without any belt tension, it pivots nice and straight. But as soon as it's loaded with the belt and has to tension it, it takes on a funky angle.

It wasn't loose on the block. The pulley turns smoothly and quietly enough. Spring feels normal when I wind it up with a wrench. But something is letting it deflect as it loads. I determined that the arm just sorta twists relative to the base as it loads up on the belt. Looks like an OEM tensioner; it has a Ford part number.

Here's a short video of the action. Hopefully you can see that, while I'm holding the wrench and keeping tension off the belt, everything's nice and straight. But as I release the spring, and belt tension loads up, the whole thing gets canted.

Is there something in the pivot mechanism of the tensioner that wears, and no longer allows it to track straight? BIG question is, is it safe to drive it this way, aprx. 450 miles, before I have a chance to replace it? Any recommendations on a FLAPS-available brand?

Anyway, here's the vid:

YouTube - tensioner

 

Humm, well something does appear to be a bit off. I'd imagine you'd be ok on a 450 mile trip, just be sure you have an extra belt just in case. If you're looking to replace it, you've got a couple options:

1) get the 'upgraded' factory replacement unit. It has a longer arm and is 'suppose' to be better. this is the one I'm running currently. Amazon.com: Gates 38119 Belt Tensioner Assembly: Automotive Just be sure you do not reuse the factory washed, just the bolt as it recesses into the unit.

2) Upgrade to the SD Double pulley unit. Thank Jose for this picture:

This is what I will be doing next go around. The factory location will need some modification, see here: http://www.thedieselstop.com/faq/949...les/982314.pdf

Safe travels either way

 

Wow, quick reply, thanks Rob! So the SD double-pulley job replaces both the original tensioner and the fixed ribbed idler next to it, right? What's the advantage? I suppose by swinging both pulleys, it's able to achieve more tension adjustment in less angle.

Well fortunately the Gates 38119 is available locally at O'Reilly, so I think we'll go for it. I don't relish the notion of swapping the belt on the side of the Interstate. Thank goodness it's an easy swap; already checked, no seized bolts.

Edit - hmmmm, O'Reilly has a Gates version of that double-pulley job for actually LESS than the 38119. It's a 38191: http://www.oreillyauto.com/site/c/de...0074&ppt=C0007 any idea if this is a good part?

 

Yes, 38191 replaces fixed ribbed idler. Just note if you go with that one, you will need to modify the factory bracket per that that .pdf document I posted above. Gates makes good stuff, so can't go wrong with either.

38119: Don't use washer from factory tensioner, just the bolt
38191: Requires modification to bracket. See here: http://www.thedieselstop.com/faq/949...les/982314.pdf

The 38119 will be your bolt on replacement if you don't feel like messing with the bracket before your trip

 

So that boss that has to be cut off is the one that holds the original fixed pulley, right? Hmmm, yeah I dunno if I wanna try anything "irreversible" the day before the trip. I assume you could just buy a base/bracket for an SD, right? But I'll bet that's dealer only, and more than a buck and a half.

 

Yes, not reversible as you mentioned

Yes, I believe you can just get the SD bracket, unless other accessories moved on the bracket from OBS-> SD. It would probably be a bit from the dealer... or you could try the scrap yard. Also, I should have noted that you need a longer belt with the SD tensioner.

 

After just replacing the tensioner and idler (again). The Ford / Motorcraft parts are superior to any other I've found. Bearings are NTN made in Canada IIRC.

 

looking at your video, YES the belt tensioner is shot. So you have to do some of what was written above for sure.

 

Jose! Thanks for posting that information originally, stole the link and pic from there

 

IDK but in the SD the alternator its in the drivers side and the AC compresor in the pass. side, so maybe they are different, I really dont know.

 

Thanks everyone. Wife is picking up the 38119 today, so we should be back in business soon enough. We'd go the SD mod route if we had time on our side. Belt is one of those HD green-back Gates, only a few thousand miles on it, so it should be fine to keep in commission.

Edit - R&I took all of fifteen minutes. Belt runs smooove. Thanks again for the links, etc. SD upgrade may be in the works someday for the RCLB.