Any ideas what's the big bolt size for adjusting AC pulley? I was thinking about getting a stronger replacement for the current one.

Also diff is attached to rear a-frame from the bottom with 4 bolts in a square. I had to use one of them somewhere else(while replacing a frame bushes) and cant find the size now on JCP website and currently driving with only 3 in there.

 

Hi katar83,

You don't mention the year or model of the Jag you're working on, but assuming it's an X300, do you mean the long bolt that adjusts the A/C compressor belt? If so, as I recall it is a special square-head bolt, at least it was on a '96 on which I recently replaced the drive belts. I don't know if you could find a suitable replacement in a hardware store, and it's a discontinued part both at Jaguar and Land Rover.

Regarding the A-frame to diff bolts, I don't know the specific size but I would guess 10mmX25mm or 12mmX25mm. Why not pull one of yours and take it to a good hardware store and match it up?

Cheers,

Don

 

M8 for the a/c idler pulley: https://www.jaguarforums.com/forum/x...lt-how-102387/
TOyota's 90119-A0169 is a nice one.

 

The diff bolts through the lower subframe I get to be M12x 1.25pitch 20mm long,
got mine out at the moment so just measured them, grade 8.8 so should be easily available.

 

Thanks Richard, bolts ordered!

Re the AC belt adjuster, yes, its for x300 and its the attached large sucker that I'm trying to get out. I've wired brushed it and tried to undo it but of course I've stripped the end at ~200Nm+. The whole thing appears to be fused together for good and this is the fourth adjuster where I've stripped the end while undoing it. The only way to get it out so far was to weld a large nut over the stripped end, that did the trick every time but I thought about replacing it entirely this time and just use nuts each side of the bracket.
The whole bracket is currently soaking in Deox-C and I'll leave it until tomorrow so will be completely rust free in the morning, maybe that will allow me to undo it, if not I'll have to get the welder out.
Gates pulley fits perfectly, the old bearing is shot completely

 

Success!

Got everything out of the Deox-C this morning, tried to undo the bolt again but no go, stripped the thread even further. I was going to get the welder out but first tried to heat up the whole thing. 15 minutes with a torch and the bolt finally came out!
Replaced bolt with a new one and all is good, just need to paint it now.
Not sure about the bolt size, its M14 head, but don't have a gauge to check the pitch, looks like 1mm though.

 

When you say M14 head do you mean the spanner size ? because typicaly an M14 bolt would need a spanner size of about 22 mm.

 

Yes, the spanner size for the bolt I've used is 14mm.

 

Ok, The thread size is most likely M8 then, standard thread,

 

Got mine mounted some time ago, regassed AC and so far so good, no leaks that I can see, all works well including new AC belt pulley.

Also re the bolts that hold the frame to diff, out of 4 bolts there only two are short ones, the other two are ~50mm and of course I was missing the longer one...

 

Oops, Sorry about that ! they were all in a box and I didn't look hard enough !

 

Funny how this turned out. My cheapo alternator replacement failed after 6 weeks of replacing original alternator, last weekend, and while fitting another replacement, I've noticed that the AC idler no longer has a bolt holding it and the only thing actually keeping it from falling off was a groove in the plastic pulley made by the belt and the belt itself 🤣
I did not remember what size the bolt was so googled it and that brought me here where I've asked same question all these years ago.
The only thing I wanted to add here for possibly future me again, is that the bolt holding the idler is indeed M8, it has to be 20-25mm long. B&Q does not sell them(30mm shortest which is too long) but Halfords in UK does, where washers can also be purchased along the "never come off juice" Loctite threadlocker which is clearly absolutely needed here.
Locally sourced replacement chinesium alternator was again fitted(hopefully lasts more than 6 weeks) and the AC idler sorted in the parking lot and I could continue on my journey with AC on.

 

I have attached photo of a couple of tools I specially made to facilitate belt adjustments on my XJR, they are a long & short version to suit requirements.
Basically, made from old XK engine studs with 1/4" drive sockets welded on. The 1/4" drive is the required size for the adjusters.

John Herbert
1996 XJR