belt tensioner bolt size.

[genpk]

well thought id have a look at the idler pulley and belt tensioner pulley today- simple job, done it before- yeah - what a pita!!
On the bolt head on the tensioner tried a 9/16 socket- to tight, tried a 15 mm to loose, everytime i just started to get close to being able to put the locking pin in the socket would just round out- end result a fairly rounded bolt head!
What hell size is the bolt ???
Only way that will ever be adjusted is by cutting the belt and unbolting the
whole tensioner unit!!

[drover]

Actually never knew of a locking pin, only ever took off tension to remove or replace belt on others but then adjuster would have a socket drive end not a bolt head....................... Not much between a 9/16 and 15mm, will have a look when i get a chance if nobody chimes in before.

[genpk]

Did a bit reading, seems a common issue as the cast aluminium bolt head is soft.
I found the factory tensioner unit is a Gates unit.
Can find very little info re socket size excepting that Gates make a kit with an extension bar and a 13,14,15mm sockets.
Have a feeling might just cut the belt , remove the tensioner and if ok either file the hex cast nut so a socket will fit or just put a new one on.
Unless you can get a socket on good and hard first go the tensioner adjuster bolt head will just chew up.
Might try one of those extractor sockets and see if that can lock onto somthing.

[OLMATE]

On bolts/ nuts/ Drain plugs, I make it a habit if I haven't undone them in the past to Always use a 6 point Socket where practical, it reduces the chances of rounding the head by 99.9%.
I know on some vehicles the pulleys bolt is a LH thread, I'm sure someone who's been there in regards to the one on the Jeep will jump on and clarify it for you

[drover]

Had a look at mine, certainly would need to remove the shroud from around the lower section and I would be using a multi point socket with a long bar or a long ringy and be lifting it towards the drivers side from underneath to get the leverage to slacken the adjuster enough to get belt off....coming from above you wont have the leverage at all, if you cut the belt it will release the tension very quickly and its highly possible the shock will cause the spring can snap or fail.............

Since the head has been chewed then a plumbers monkey wrench or one of those multi grip type ring spanner affairs is your only hope, your after leverage.

[genpk]

Well ,removed the plastic cover ( 5 bolts- 2 from the top, 2 underneath one on the drivers side from underneath) after trying every type of socket, belting smaller sockets on etc , bought some of those locking sockets, still no good, just kept ripping it up the head so eventually got a length of 19mm x 19mm wood about 55cm long, got a jack under the car, jammed the wood under the munched up bolt head and jacked away, it worked, was able to put a lock pin in (small allen key)
Then unbolted the tensioner (2 bolts) , trick is to get a bit of coat hanger wire or a small bungy cord and hook the belt where the tensioner pulley is and attach the
wire to something to hold the belt in place while you remove the tensioner.
I had another used tensioner which had a good bolt head adjuster on it so i took the bearing and pulley out, popped the dust covers off the bearing and was surprised how little grease was in there and what was there was dry, given the car has only done 60k .
Cleaned and repacked the bearing with high temp grease, attached it to the “new” tensioner with the good bolt head adjuster.
Did the same with the idler pulley, again pretty dry grease wise , cleaned and repack.
Before i put the plastic cover back on i cut a small piece out of it to allow access
to the tensioner bolt head should i ever want to just change the idler pulley without having to pull the whole cover off to get to it.
As a matter if interest i attempted to grind the bolt head on the old munched unit so it would fit a smaller socket, no matter what i did, the alluminium bolt head just kept stripping. My thoughts are Gates do not want people to service the tensioner and probably think you will buy a new one as the allunimium adjuster is so soft you might get one go at it with the right socket.
Im still not sure of the size but when i put the used tensioner back on i used a locking type 15mm socket which worked.

[bjm]

Had two plastic name brand plastic idler pulleys fail in a year on my 2012GC diesel .The bearings were cheap rubbish with little grease.Switched to metal
pulleys running quality Jap bearings that can be replaced,no more failures.!