Tensioner assembly and belt change

[LithiumCobalt]

So, as I continue working on my '87 in anticipation of actually being able to drive it in the next few weeks, one of the last items on my list is to change the engine belts (got two new Motorcrafts). I got the front one off by loosening the alternator, which wasn't too bad other than I had to remove the top brace for the alternator because otherwise I could not pivot the housing far enough to give enough slack in the belt. How in the HELL does this tensioner assembly work? As I understand it, there's a bolt on the front plate under the A/C compressor and one directly behind the tensioner on the back side of the bracket. I have read several threads and tried finding a you tube video showing how this contraption operates and I am still confused. Read my service manual and that was not very clear either. What is the correct order of operations, step-by-step? I am used to later models with the self-adjusting tensioner - slip the breaker bar in, release, remove belt, release, put new belt on and go. This one seems a bit more finicky as it does not self adjust? I need someone to post a couple of photos or a video so I don't fuck up my car. Any takers?

It also appears that the pulley is riveted to the tensioner. Looks like I will returning the plastic replacement that I bought. Don't want any plastic bullshit. Would really like to replace the unit before new belts just to make sure everything is up to snuff, but I wonder if the part is even available anymore anywhere?

[91waggin]

IIRC, you put a wrench on the front bolt to get the tension, then you tighten the back one to hold it in place. Does that make sense?

[Piece-it pete]

The tensioner isn't hard, iirc the tensioner bracket is a two bolt setup like the alt, one pivot bolt and one bolt on a curved hole to tighten. If you monkey with it you'll figure it out.

I used a ACDelco 15-20669 tensioner pulley. It fit fine but I think had a slightly smaller diameter than stock. I think mine had a bolt holding it to the bracket, I don't remember, but you could drill out the fixed one or find a bolted one at the junkyard.

Pete

[sly]

loosen the pivot bolt at the AC compressor (DO NOT REMOVE). then wrench behind the mounting plate to loosen the positioning bolt. reverse with a breaker bar holding the tension on the tensioner for install. I've contemplated many times trying to figure out how to put an aero/whale tensioner on that side. Never actually done anything about that though.

the stock pulley is held on with a snap ring under the metal grease cap that is pressed on and a holy hell of a bitch to get off (re: can opener in the form of punch/chisel).

[gadget73]

I have a Motorcraft replacement on mine, and its bolted. Metal idler too. I bought it years ago though, so its hard to say what you can get now. If you can get the pulley off, just replace the bearing. I rebuilt the one for my truck. The bearing was like $8 or something from McMaster-Carr.

[85crownHPP]

It's kind of a PITA the first few times you do it, because you have to come in with a socket + extension from back behind the AC brackets, you can't really see it too well either.
You should see a square 3/8" hole in the tensioner arm you use to crank on the thing to make your tension, then hold it with one hand and tighten either of the two fasteners you just loosened with the other.

[HiFiMerc]

Much easier if the smog pump isn't present.

[sly]

Much easier if the smog pump isn't present.

This!

done it with and without though... just can't swing the ratchet on the back side as far with the smog pump present.

[LithiumCobalt]

So, if I understand right, loosen the bolt on the front side first, then loosen the bolt/nut on the back side. This should remove tension and I can remove belt. Replace belt. Use breaker bar to apply tension and then tighten bolt/nut on rear side. Tighten bolt on front side. Done. Sound right?

One thing I noticed was that I couldn't get the right angle to get my breaker bar inserted firmly into the square opening with the belt in the way (too deep/recessed to reach with breaker bar). I will investigate that a bit more. Perhaps I need to put the breaker a different direction while doing that or use an extension.

Lastly, since I don't have any special voodoo equipment for determining belt tension, how tight should they be when installed properly?

All very good advice so far! Thank you guys! Still learning the 5.0

[sly]

Yes, that's pretty much it.

I had to use my 4 inch extension on my breaker bar to get it.

as for tension of the belt... good and, but still allow about a quarter inch of deflection on the long run without pushing real hard. If it squeals when you turn on the AC compressor, tighten it some more. If not, you're good.

[RyPow]

Edit: Sly beat me to it, but here goes anyway:

So, if I understand right, loosen the bolt on the front side first, then loosen the bolt/nut on the back side. This should remove tension and I can remove belt. Replace belt. Use breaker bar to apply tension and then tighten bolt/nut on rear side. Tighten bolt on front side. Done. Sound right?

Done. That's the correct procedure. A ratcheting wrench (GearWrench) comes in handy for the back bolt, as long as it's not too seized up.

One thing I noticed was that I couldn't get the right angle to get my breaker bar inserted firmly into the square opening with the belt in the way (too deep/recessed to reach with breaker bar). I will investigate that a bit more. Perhaps I need to put the breaker a different direction while doing that or use an extension.

A 2-3" extension should do the trick.

Lastly, since I don't have any special voodoo equipment for determining belt tension, how tight should they be when installed properly?

There are different schools of thought on belt tension, but my experience has shown me that there is usually a "threshold" where the belt goes from somewhat tight (1/2" deflection or more over ~18" length) to rock-solid (less than 1/4" deflection over 18"). I try to hit just shy of that threshold. It's all about having the belt just tight enough to avoid pulley slip, since the life of your AC/PS/alt/smog/tensioner bearings will obviously be shortened by excessive tension. If you get belt squeal (and are reasonably confident in the condition of your accessories, ie. they are not seizing up), cinch it down a little more.

[LithiumCobalt]

You guys kick ass! Thanks! Hopefully I will be able to finish this up in the next few days. Only so much time to get everything done. My car has been sitting for about two weeks. Coolant is drained, hoses off, many clamps replaced already, oil/filter/cap/rotor/plugs/wires/thermostat all changed, pcv system serviced, power steering lines replaced. The belts are the last thing on the major mechanical list. Once I get that done, I am going to have a shop replace rubber brakes lines, fluid and maybe rear cylinders if needed and this baby will be road ready for summer! Then it's on to minor things like exhaust repair, paint touchup, trim fixing, etc.

[LithiumCobalt]

Had success changing the belt. Old one was cracked to hell so I'm glad to be rid of it. One thing I have found, though, is a ton of oily residue covering the air pump and tensioner assembly bracket and in the general area. Not sure where it is all coming from, but I cleaned it all up. I've found this car to have a fair bit of leaks for as low mileage as it is. I guess age trumps overall.

[LithiumCobalt]

New question. Does anyone know what the proper length for the alternator belt is supposed to be? Ordered Motorcraft JK6-502 (50.25 inches) from Rock Auto as it was said to fit and I cannot for the life of me get the belt slipped over the alternator pulley and that is with the alternator bolt completely out of the top. If I take the pivot bolt out, I can get the belt on, but cannot get the pivot bolt to line back up through the holes since there's so much tension tweaking on the alternator housing. That fucker is tight. I see JK6-506 (50.75 inches) that I could try to special order through O'Reilly (RA doesn't even show it) if they can even get it. I took off a Gates K060505 (51.052 inches). Anyone have any sizes or part number? Thanks.

[85crownHPP]

The 505 is definitely the 'long' belt part number - the 500 is what most of us use, so the 502 Ford belt should have been fine...

Does your Lincoln have the large externally regulated alternator or a 3G swap? That would explain it.