That sounds similar to the arangement for the earliest XKs. The regulator was tapped into a fuse that also fed the fuel injection & starter relays.
Not the brightest idea obviously. Jaguar had wised up by '98 and given it a dedicated feed.

The 2003 diagram (newest I can find), shows two feeds to the regulator: F2 (5A) ignition switched in the engine compartment fusebox, and F22 (5A) permanently live in the trunk fusebox. I'm not sure of the latter's purpose.

 

Update:

We had a relatively cool morning today so I decided to tackle the alternator removal job. After putting the hood into the upright service position, I still had no working room in the engine bay with the fan shroud assembly in place, so I managed to completely remove the fan shroud assembly after battling it for awhile. That certainly opened up more room for hands and tools. But I ran into a problem that I did not expect: When I put my 15mm socket on my breaker bar and place the socket on the nut for the accessory drive belt tensioner pulley in order to rotate that tensioner arm counter-clockwise so I can loosen and remove the belt, all I do is unscrew that nut. What tool is needed, where do I place it, and how do I properly rotate that tensioner arm in a counter-clockwise direction so it will slacken the belt and allow me to remove it?

 

Update:

I figured out how to rotate the accessory tension arm using a 3/8-inch breaker bar inserted into the 3/8-inch square hole at the top of the tension arm (I had not seen this hole earlier), and managed to slip the belt off of the alternator's pulley. Then jacking the front end up and crawling underneath the engine compartment, I removed the two alternator cooling duct plastic pieces and managed to unbolt the battery cable from the back of the alternator. I can now get my hand on the 3-wire plastic electrical connector that plugs into the back of the alternator, but I have been unable to figure out how you unplug that connector. Are there tabs that must be pushed or squeezed, is it popped off with a screwdriver, or what? JTIS does not tell me, and I certainly do not want to force it and wind up breaking it....

 

There is a locking device. Here's some pics of the reg and its associated plug:





It is a tight fit, but IIRC there was enough slack in the harness to leave it in place until the alternator was loose so I could get better access.

 

Thanks Michael. I assume that the regulator assembly is inside the alternator housing. Is that correct?

And do you remember how the "locking device" on your electrical connector unlatches? I have tried squeezing it, wiggling it, and pulling on it with no luck. I surely do not want to break or crack any of its plastic shell. Only being able to get one hand to it certainly does not help. Perhaps it is also stuck firmly in place after more than 13 years since the car left the factory. Wayne (cjd777) suggested that I spray a liberal portion of contact cleaner spray on it and let it soak overnight, so that is what I am doing....

By the way, your stock photo of a new clip and harness does not appear to match what I have. The stock photo looks like it has a tab that you push down on. I neither see nor feel such a tab on my clip. Bummer....

 

Yes, it's underneath the rear cover:- see below. I did partly disassemble the one I took out (I'm nosy).



My take (in the absence of a functioning memory) on the locking tab is that it's to be prised away from the body of the harness plug, while pulling on the plug. I do remember its being a very tight fit which is why I elected to leave alone until I'd removed all the bolts and could juggle the orientation of the alternator. I'm fairly sure you have the same arrangement as the regulator part # (JLM20187) hasn't changed over the years.


Last time I replaced the alternator on the MGB it took around 30 minutes, but that doesn't have a V8 under the hood...

 

Well Jon, that answers that, small screwdriver, nothing pointed.

Wayne

 

Wayne,

Maybe no screwdriver is involved. Jan found a June 2018 post in the XJ section of the forum last night that mentions a tab on the side of the clip that faces the engine block (where we cannot see it and I can barely get my big fingers around it) that must be squeezed extremely hard while pulling the male part of the clip outwards. The owner reported that he had a hell of a time removing it. Other owners mentioned using pliers but warned of breaking the clip while doing so....

Jan showed me a couple of photos contained in one of those posts. The clip in those photos looks exactly like ours, so that is very encouraging. Lo and behold, there does indeed appear to be a locking tab on the unseen back side of the clip in the photos. The question is how do you get to it, and what do you do with it. I sprayed the clip assembly with contact cleaner spray last evening and will let it penetrate today before tackling it again. Perhaps that will help....

And I ordered a new Gates K060910 serpentine belt from rockauto.com last night. The factory belt looks marginal after 13+ years and 115,500 miles. I see small surface cracks in some of the ribs. The new belt should show up here on Thursday....

 

Update:

After working through some higher-priority requirements in our lives this week, I was able to get back on this alternator removal job this morning. I was never able to get my monster fingers around the 3-wire alternator electrical connector clip in order to squeeze the release tab and have enough room to pull the clip out of its socket. So I left the clip plugged in, removed the lower alternator bolt, then removed the upper alternator nut. I was then able to put both hands on the alternator casing from above, shake it loose from its mounting, and pull it out without having to use any pry tools. Once I had it out, I spun it around to where the back of the alternator was facing up at me. At that point I could easily get a hand on the electrical clip, squeeze its now-visible release tab, then pull the male part of the clip out of its female socket on the alternator. I then worked the alternator up to the top corner of the radiator, pulled the upper radiator hose from the radiator, and finally lifted the alternator free and clear of any obstruction. By the way, removing the oil filter gave me a straight shot at the alternator's lower bolt's nut with my 15mm wrench from underneath the car. With the oil filter out of the way, there is much more tool-maneuvering room in that general area....

I then drove the alternator to a highly-recommended starter-and-alternator refurbishing shop. I expect it will be ready and hopefully better-than-new by the middle of next week.....

Thanks to all who have contributed various tips and tricks in this thread. You have been of great help and it is much appreciated. We shall see how the re-installation process goes once my refurbished alternator is back in my hands. I will also be installing the new Gates serpentine belt that arrived in yesterday's mail before putting everything back together again....

 

Nice job, Jon. This is one of those jobs you can do in 1/2 the time 2nd time around. I hope that's true for your installation!

most of us, me included, just buy a new alternator. A Denso brand one cost me $420. If you can please give us a heads up about what a regulator rebuild might cost. I'd love to learn.

I suppose, when you think about it the only thing that'll fail is the rectifier (diodes ) or the volt regulator. I bet it's super rare for any of the alternator components to fail.

John

 

John,

Thanks for the attaboy. This job is certainly not much fun when you have to do it during our hot and humid summers. And JTIS says nothing about having to remove the fan shroud assembly. There was no way I could do this (or change the serpentine belt) without getting the fan shroud assembly out of the way first....

My alternator refurbishment cost should run between $125 and $150. That will include a new regulator, new diodes, new bearings, a new internal plate of some sort, and possibly a couple of other small components. I will report the full tally once the alternator is back in my hands with the paperwork indicating exactly what was done....

 

For those of you who have already done this job:

I have read about the bushings in the lower alternator bolt's housing shaft needing to be pushed back into place before you can re-install the alternator. What are the best ways to do this? I am not sure if my bushings indeed moved or popped out slightly when I removed the alternator, but I want to be prepared just in case they did....

 

Sounds like you got the alternator out from between its mounting flanges without a fight, so the odds are you'll be fine as you're putting the same one back.

If you want to make doubly sure you can make up a puller from a long nut & bolt, using a suitable sized socket on the bolt to allow the collar to be drawn inside it.
Or you could try the ball joint splitter as there's more room to manoevre with the alternator out of the way. Only needs to move a couple of millimetres so the alternator flanges can slide in.

The collar will slide back to close up any gap when you torque the mounting bolts up on reassembly.

Shame you had to remove the fan shroud: maybe the plumbing is just different enough on the 4.2 to mandate it. Those retaining bolts are a design masterpiece

The refurb charge seems very reasonable given what's being replaced.

 

Michael,

Thanks for your recommendations. I hope you are correct in speculating that my lower bolt bushings probably did not move since I was able to pull the alternator out without prying or pounding on it. We shall see how much of a fight it will put up when re-installation time rolls around (probably next weekend)….

By the way, why couldn't the appropriately-sized C-clamp be used to crank any protruding bushing back into place?

 

Never thought of the C-clamp - possibly because the only one I have is so old and so large it was probably a leftover from the Titanic build.
With a suitable socket in the middle, I don't see why not?

 

Update:

The refurbishing shop just called me to say that my alternator is ready to go. New regulator, diodes, brushes, bearings, etc. (their standard refurbishment process). My total cost is $120. I will pick it up tomorrow morning and hopefully we will put the car back together this coming weekend. Stay tuned....

 

Wow, you just saved around $300 on the parts alone! Ttytt when I read "it's ready to go" my mind went to "unit at death's door " - glad you meant ready to pick up.

John

 

Picked up my refurbished alternator this morning. The cost was $128 including tax. I asked if they accept alternators and starters that are shipped in for repair and then shipped back to the owner. They said yes, they typically do this 4 or 5 times per week. The shop is Alamance Starter and Alternator Service Inc.in Burlington, North Carolina. The owner is Mark Greeson. His phone is (336) 228-9654.

We plan to do the re-install on Saturday morning and then put the car back together. Stay tuned....

 

Update:

We finished the job today. My neighbor came over to help - he worked from the top of the engine bay while I worked underneath the car. Very much appreciated and it goes faster with two sets of hands. My refurbished alternator settled back down into its mountings in seconds. No forcing in of any popped-out bushings required. I made sure to connect the 3-wire electrical clip BEFORE I oriented the alternator into final position for bolt-down. Although we took phone photos of the old serpentine belt before we removed it to install the new belt, the photos were a bit fuzzy and did not provide all the detail we needed. Many thanks to Gus for providing me with the proper drawing of how to fit the new belt - that did the trick for us. The fan shroud assembly settled down into position much easier and faster than it came out, which really surprised me. After that, the rest of the job was just putting the car back together again while being sure to follow my notes in the proper sequence....

Putting the hood into the vertical service position is a must for this job - that really opens up hands-and-tools access to both the alternator and the belt....

Topped up the coolant (we spilled more than we originally thought we did while pulling the upper radiator hose to work the alternator back into its final position and then to lower the fan shroud assembly into position), installed the oil filter and filled the engine with fresh oil, re-installed the battery, re-set the windows, then cranked the engine to ensure that it ran smoothly with no dash warnings. It ran like a top and the red battery icon on the dash went off and stayed off. My multimeter read 13.5 to 13.8 volts at the battery terminals with the engine idling, so the alternator appears to be charging normally again. I took off on a ten-mile test drive and had zero issues....

I will check the coolant and oil levels first thing in the morning for the next several days and top up as necessary....

Thanks to all that offered your valuable suggestions and provided experienced guidance. It is always very much appreciated....


P.S. -- This job would have been much more enjoyable in our October / November timeframe. Having to do it in our July heat and humidity was no fun. I have downed more than a gallon of ice water in the past couple of hours and will probably drink a gallon of cold Gatorade for my supper tonight....