Alternator Questions
 

I have been reading all the threads I can find on alternators. There seem to be a lot of differences of opinion. I want to get a new alternator and possibly move it to the air pump location which I would like to remove. I am hoping to find the easiest way to do this. What is the best replacement alternator and what needs to be done to relocate? (brackets, pulleys etc.) Will there be a problem driving the AC and Alternator with same belt?

Thanks for any suggestions...Jimmy

I got the GMALT from John's Cars... Jaguar XJS conversions, parts and advice from John's Cars ...and put a higher capacity GM alternator on (cant remember its power rating right now, but it's over 100 amps). His kit works as described, just bolt it on and provide your own alternator.

FYI, this leaves the air pump bracket free for when you decide to ditch the compressor in the V and put a smaller compressor where the air pump used to be. I used a Sanden from Vintage Air.

John
1987 XJ-S V12

So this GMALT($75) is a kit to install a GM alternator in the original alternator location? What is the A7294NEW ($118.33)? This doesn't help me move the alternator to the old pump location. My AC works fine so not interested in moving it.
...Jimmy

My GM alt is upper right where the air pump would have been. Mine uses a 1988 RS Camaro V6 (that gets me the right clock position on the mounts/plugs) I just have to swap out the pulley.

Jimmy,

Most down here that fitted the alternator where you want, returned it to the OE position shortly after.

Their reason, not mine:

The tension required on the belt to drive the a/c compressor was too high for the alt bearings, and failure was common. AGAIN, what I was told.

I fitted a Bosch 115amp from an XJ40, and simply changed the pulley to a "V" to suit the standard alternator belt, and fitted it where the Lucas alternator was. I then removed that air pump bracket and replaced it with the Jag idler bracket and arm for the a/c drive.

OK, the Bosch and XJ40 are common down here, the GM, Delco, AC, etc are not.

Back in the early days when I was having alternator issues, I wondered who on earth put that thing in such a stupid place, but once I stopped messing around and replaced the Lucas with a Bosch, with upgrade, then I upgraded the wiring at the SAME time, I have never been back, and that was all done in 1996, and apart from a belt every 5 years, it is a forgotten item.

Your market makes decisions very different to mine, but I also looked at the alternator shift (I read The Book), but I reckoned it cluttered up that area, then the belt tension raised its head.

Sorry, no "belt, bearing, tension issues at least from my experiance. Mines been there for well over 8 years. No problem with it or the a/c what so ever.

Replacing a failed unit or upgrading? I'm fairly sure that your '94 V12 already has a decent, high output alternator....probably Bosch or Nippondenso. Might be worth keeping.



Cheers
DD

The 94 should have a 115A alternator, unless it is/has failed no point in upgrading.

Good note Doug and Warren.

I did not see the 1994 MY, just assumed, must stop that, it was an 5.3 HE that we all play with.

I have noticed weakness in charging (gage movement). I am replacing hoses, belts, fan clutch. While all that is out would be a good time for a new alternator, which looks like it has been there from birth.

After reading some of these posts, it may be easier to keep alternator in original location. I do want to get rid of the air pump. Where can I get an idler to replace the pump?

I saw a 120 amp Bosch alternator (reman.) at PartsGeek.com for $190. It is suppose to be a direct fit. Anyone have any suggestions on alternators (that don't require a lot of mods.?

Thanks...Jimmy

Just to throw out an alternative to buying something off the shelf.....


Over the last few year I have stopped buying off-the-shelf alternators and starters. Instead, I use a local starter/alternator rebuilding shop. Most towns have such a specialist. My experience has been very good with a 100% success rate versus 50% success rate with off-the-shelf rebuilt units

Cheers
DD

Hi Jimmy
One modification you can do.
Set up a pulley small diameter from X308 (JLM20235). It is less than 3mm.
And also, it is direct fit.
https://cimg4.ibsrv.net/gimg/www.jag...e6a0de516b.jpg


https://cimg0.ibsrv.net/gimg/www.jag...78d4ebc362.jpg

Jimmy:


Don't fall for the fallacy of diagnosing alternator health via the dash guage. Notoriously slow and inaccurate. Not really gauges, but only indicators.


I made a patch cord for my VOM. Plugs into the cigar outlet. Much better data.
Volts in real time under various load and RPM's.


The Delco's can indeed be "clocked" to suit plug in and ear locations.


Carl

Jimmy...might want to keep in mind too that if you move the alternator to where the air pump is, or was, that puts the alternator in a place where it will get even less airflow than it does now. I think the alternator needs a decent amount of airflow to keep the diodes cool, and moving it further up *may* reduce the airflow to it, which may result in a failed diode (which I've experienced).

Just a thought.

Thanks,

John
1987 XJ-S V12

I am leaving it...but need to find a pulley to replace the Air Pump.
Thanks...Jimmy

Do not use the dash gauge to verify alternator charging. Connect a volt meter across the battery and start the car. Charging voltage should be about 14-14.5 volts

A fully charged battery should be at least 12.7 volts when disconnected at 12.2 volts the battery is only 50% charged.

With the air pump out, the alternator is so easy to get to that I will leave it in it's location. I am going to try the Bando 3430 belt solution for the AC and no tensioner pulley. Not sure if same length for the 94 as earlier models. I will check the length first.

I am considering how to plug the exhaust air holes for the air pump. I have read several solutions on this forum, and they all sound fine. I'm headed for Lowes this morning for parts.

With the pump removed, I will have an engine code, any way to stop this? The electrical wire that went to the pump clutch, should it be just taped off?

Thanks guys.....Jimmy

I believe my 91 is the original Bosch alt located in the original location. It says it's rated at 140 amps. It looks pretty heavy duty to me and 140 amps should handle anything I throw at it.