Serpentine belt tensioner

[NeilMc]

Hi does this look or sound right? Its a legacy diesel my 12. Is tensioner bad or can it be adjusted/tightened.

Many thanks

Neil

[poconoracing]

We don’t have Subaru diesel here in the states, but that looks like the spring in the tensioner is broken. You’ll need to replace it.

[NeilMc]

Thanks are they hard to replace

[cww516]

Unless the tensioner has already been replaced by someone who installed it with plenty of silver Loctite (aka cross-threaded the bolt), it's pretty straightforward. That tensioner looks a little different from what I've seen on gas-engine models here, but judging by the direction it's pushing on the belt, there should be a 1/2" (13mm) square drive on the arm somewhere. Might make your life easier to take the engine cover off first, just to have a little more room to operate, but you'll plug a 1/2" ratchet wrench into that square drive and pull counter-clockwise to relieve the tension on the belt, and pop the belt off of one of the pulleys and let off on the tensioner. Replace the tensioner, look at the belt diagram sticker and scratch your head for a couple minutes, loosely route the belt, use your 1/2" drive ratchet to pull on the tensioner, and slip the belt back onto the last pulley. Assuming you have a flat-ish multi-rib belt and not a pair of vee belts, make sure all of the ribs are in the right grooves on the grooved pulleys, and the flat side is more-or-less centered on the flat pulleys.

 

While you're at it, this wouldn't be a bad time to replace the belt (assuming that hasn't been done recently), since you'll be in there anyway. Couldn't hurt to spin/try to wiggle the idler pulleys, too, just to make sure the bearings are still good. You'd be able to hear them if they were bad, but like I said, you're already in there, may as well.

[NeilMc]

Thanks so much for that, ill defo scratch the head once or twice