XJ6 & XJ12 Series I, II & III 1968-1992

Alternator belt broke--how to replace?

 
  #1  
Old 01-22-2012, 09:35 AM
Veteran Member
Thread Starter
Join Date: May 2010
Location: Arlington, VA USA
Posts: 6,290
Received 452 Likes on 378 Posts
Default Alternator belt broke--how to replace?

Well I got the HVAC on my car running, and when I turned it on for the first time, I heard some squealing sounds. At first I thought it was the HVAC blower motors finally coming on after a long slumber, but then the noises stopped and I decided to go for a drive. Then the tach started going wacky and my headlights were very dim!

Then the car just flat out died and I got out and smelled burning rubber and the alternator belt had just completely torn. I'm guessing running the HVAC put additional load on the alternator, which made the pulley harder to turn and caused the belt to slip. (Does that sound feasible? My friend insists that no matter how much load you put on the electrical system, the alternator is always freewheeling and that my theory is impossible!) Apparently the alternator belt has broken before by the previous owner (perhaps a couple years ago?) but I checked the pulleys and they do look like they are properly aligned, at least with a quick visual inspection.

Back on topic...

How do I replace the alternator belt? I know there is a locking bolt on the alternator and a tensioner, but there are two other belts in the way, and they look like a big pain to get off. Are there any tips for doing this job (removing the other two belts blocking it in?). Do I need to remove the fan?!
 
  #2  
Old 01-22-2012, 10:52 AM
Veteran Member
Join Date: Mar 2008
Location: Pacific Northwest USA
Posts: 20,148
Received 6,550 Likes on 4,861 Posts
Default

Don't need to remove the fan.

Of course if other belts are blocking, they'll have to come off first. I can't remember the order of the belts on a Ser III

On any of the belt driven devices you'll have to loosen the pivot bolt a bit before using the turnbuckle-style adjuster

I recall that, in some cases, the adjuster might have to be disconnected at one end to allow the alternator (or whatever) to swing far enough to get the new belt on

Hope this helps a little. It's been too long ago for me to give a bolt-by-bolt description

Cheers
DD
 
  #3  
Old 01-22-2012, 11:01 AM
Senior Member
Join Date: Aug 2011
Location: Falls Church, VA
Posts: 114
Likes: 0
Received 21 Likes on 19 Posts
Default

does the alt belt drive the ac compressor, too? Remember this is an automatic climate control system, so I'm thinking maybe the compressor took the belt out as the squeeling and belt breakage coincided with the bringing back to life of the hvac system. THe ac amp can turn that compressor on whenever it likes.
 
  #4  
Old 01-22-2012, 11:56 AM
Veteran Member
Thread Starter
Join Date: May 2010
Location: Arlington, VA USA
Posts: 6,290
Received 452 Likes on 378 Posts
Default

I don't believe that the AC belt and the alternator are on the same belt. The AC belt still appears to be connected.

I carefully worked my way through the factory service manual and I think I have an idea of where the pivot bolts are for the power steering pump, the AC compressor and the alternator. I'll give it a shot!
 
  #5  
Old 01-22-2012, 12:51 PM
Veteran Member
Join Date: Mar 2008
Location: Pacific Northwest USA
Posts: 20,148
Received 6,550 Likes on 4,861 Posts
Default

If the battery is low and/or there's a large amperage draw (like a/c compressor, rear defogger, blower motors all on at the same time) the alternator will be under a greater load. A loose belt could slip, and an almost-ready-to-break belt could conceivably be put over the edge.

Cheers
DD
 
  #6  
Old 01-22-2012, 01:44 PM
Senior Member
Join Date: Aug 2011
Location: Falls Church, VA
Posts: 114
Likes: 0
Received 21 Likes on 19 Posts
Default

Originally Posted by Doug View Post
If the battery is low and/or there's a large amperage draw (like a/c compressor, rear defogger, blower motors all on at the same time) the alternator will be under a greater load. A loose belt could slip, and an almost-ready-to-break belt could conceivably be put over the edge.

Cheers
DD

I was also thinking along the lines of the compressor might be seized or close to it and replacing the amp, turning on the hvac engaged the clutch (thus the subsequent squeeling) and took out the belt.
 
The following users liked this post:
amcdonal86 (01-24-2012)
  #7  
Old 01-22-2012, 01:57 PM
Veteran Member
Thread Starter
Join Date: May 2010
Location: Arlington, VA USA
Posts: 6,290
Received 452 Likes on 378 Posts
Default

Well, I had to give up. The good news is all the belts seem to have been very IMPROPERLY tensioned, they are all very loose. I'm surprised they're not all broken already! Pushing down on them lightly (maybe 5 lbs of pressure) resulted in the belts deflecting about an inch. It wouldn't surprise me if the alternator belt were done the same way.

I cannot for the life of me figure out where the damn AC compressor pivot bolts are. I have loosened the bolts on the tension adjuster and the two nuts on it, but I can't figure out where the pivot bolts are! Does anyone have any idea where they are?
 

Last edited by amcdonal86; 01-22-2012 at 02:06 PM.
  #8  
Old 01-22-2012, 02:00 PM
Veteran Member
Thread Starter
Join Date: May 2010
Location: Arlington, VA USA
Posts: 6,290
Received 452 Likes on 378 Posts
Default

Originally Posted by vwtechnician View Post
I was also thinking along the lines of the compressor might be seized or close to it and replacing the amp, turning on the hvac engaged the clutch (thus the subsequent squeeling) and took out the belt.
Wouldn't that imply that the compressor belt would be the one that went out? The compressor belt is not broken.
 
  #9  
Old 01-22-2012, 03:21 PM
Fraser Mitchell's Avatar
Veteran Member
Join Date: Dec 2009
Location: Crewe, England
Posts: 7,348
Received 1,574 Likes on 1,311 Posts
Default

Does the belt for the alternator drive it alone, or something else as well ? On my UK car, which had no Air Con, it also drove the water pump.

Check that everything your broken belt drives rotates OK, and is not seized.
 
  #10  
Old 01-22-2012, 03:27 PM
Veteran Member
Thread Starter
Join Date: May 2010
Location: Arlington, VA USA
Posts: 6,290
Received 452 Likes on 378 Posts
Default

Yup, the alternator belt drives the alternator alone. The alternator spins freely. Does anyone have any idea where the pivot bolts for the air con compressor are? I just can't find them!
 
  #11  
Old 01-23-2012, 08:43 AM
Veteran Member
Thread Starter
Join Date: May 2010
Location: Arlington, VA USA
Posts: 6,290
Received 452 Likes on 378 Posts
Default

Any ideas? The FSM says there should be a rear pivot bolt and a front one--but it does a poor job explaining where they are.
 

Last edited by amcdonal86; 01-23-2012 at 08:45 AM.
  #12  
Old 01-23-2012, 03:32 PM
Veteran Member
Thread Starter
Join Date: May 2010
Location: Arlington, VA USA
Posts: 6,290
Received 452 Likes on 378 Posts
Default

I've attached a picture of an aircon compressor off Ebay that I think has a good view of both sides of the compressor. I'm having trouble figuring out how it pivots!
 
Attached Thumbnails Alternator belt broke--how to replace?-compressor.jpg  
  #13  
Old 01-23-2012, 03:44 PM
Veteran Member
Thread Starter
Join Date: May 2010
Location: Arlington, VA USA
Posts: 6,290
Received 452 Likes on 378 Posts
Default



Here's another view! I imagine if there's one bolt on the front and one on the rear that need to be loosened in order to pivot, they both need to be on the same plane. I just can't seem to see any holes that are on the same plane on the front and the back!
 
  #14  
Old 01-23-2012, 03:56 PM
Veteran Member
Thread Starter
Join Date: May 2010
Location: Arlington, VA USA
Posts: 6,290
Received 452 Likes on 378 Posts
Default



One more!
 
  #15  
Old 01-23-2012, 04:33 PM
Fraser Mitchell's Avatar
Veteran Member
Join Date: Dec 2009
Location: Crewe, England
Posts: 7,348
Received 1,574 Likes on 1,311 Posts
Default

Is there no jockey pulley to tension the belt ? If not, then compressor will have to be mounted on a bracket with some sort of relevant adjustment facility. There seems to be nothing on the pics of the compressors.

As I remember it my alternator pivoted on two lower lugs, and an adjuster at the top allowed belt tension to be adjusted.

If you have the workshop manual, it should show belt layout.
 
  #16  
Old 01-23-2012, 06:48 PM
Veteran Member
Thread Starter
Join Date: May 2010
Location: Arlington, VA USA
Posts: 6,290
Received 452 Likes on 378 Posts
Default

Yeah, the compressor belt has a tensioner towards the top, but I'm trying to figure out which bolts I need to undo.

I guess i'll just give it another shot when it gets warmer out--but there's so many nuts/bolts on that thing I don't want to disconnect the wrong one! I also don't know which way it's supposed to pivot (down? inwards?) and I don't want to break or bend the tensioner.
 
  #17  
Old 01-23-2012, 08:06 PM
Veteran Member
Thread Starter
Join Date: May 2010
Location: Arlington, VA USA
Posts: 6,290
Received 452 Likes on 378 Posts
Default





This is what I have to work with. The alternator drive belt removal instructions make it sound like there's two bolts that need to be slackened (so do the compressor removal instructions), but only one bolt is labeled on the diagram.
 
  #18  
Old 01-23-2012, 08:10 PM
Veteran Member
Thread Starter
Join Date: May 2010
Location: Arlington, VA USA
Posts: 6,290
Received 452 Likes on 378 Posts
Default

OK, I think I've figured it out. I've circled the ones I think need to be removed.

Notice that that one in the rear has a bit of a longer thread on it and is lined up with the other hole which I've circled. The compressor in the photo is actually upside down.
 
Attached Thumbnails Alternator belt broke--how to replace?-compressor.jpg  
  #19  
Old 01-24-2012, 07:38 AM
Veteran Member
Thread Starter
Join Date: May 2010
Location: Arlington, VA USA
Posts: 6,290
Received 452 Likes on 378 Posts
Default

Just reporting back--it turns out the two I've circled there ARE the pivot bolts. I've been able to get the bolts loosened and the compressor pivoted partially. Unfortunately, the nut on the tensioner is very hard to loosen because it is up against a bracket that holds the compressor to the cylinder block. So I can't get a wrench in there easily to turn the damn thing!

Almost there, though. Slowly but surely! I loosened the bolts holding the tensioner onto said bracket and the compressor, and I'll probably wedge a screwdriver in there to separate the tensioner bolt from the bracket just enough to let me loosen that nut.
 
  #20  
Old 01-24-2012, 01:34 PM
Fraser Mitchell's Avatar
Veteran Member
Join Date: Dec 2009
Location: Crewe, England
Posts: 7,348
Received 1,574 Likes on 1,311 Posts
Default

I am afraid that when Jaguar engineers designed things, the design team did not include a maintenance mechanic. So there was nobody to say " hey guys, this will be impossible to fix the way you've placed it"!

It was even worse, there were no production engineers on the team, the complete design was thrown over a wall to 'production' to sort out how to make it.
 
The following users liked this post:
amcdonal86 (01-24-2012)

Thread Tools
Search this Thread
Quick Reply: Alternator belt broke--how to replace?


Contact Us - Archive - Advertising - Cookie Policy - Privacy Statement - Terms of Service

© 2019 MH Sub I, LLC dba Internet Brands

We are a participant in the Amazon Services LLC Associates Program, an affiliate advertising program designed to provide a means for us to earn fees by linking to Amazon.com and affiliated sites.
 
  • Ask a Question
    Get answers from community experts
Question Title:
Description:
Your question will be posted in: