It looks like the alternator for my 1989 Jaguar XJS 5.3L Convertible has a Bosch alternator with an output of 115A. I increased the wattage on the headlamps and added additional lighting. Is this alternator adequate for the car or can you and should you increase the amperage output? My car has a V belt with jus a basic smooth pulley. should the pulley be changed to a V type to eliminate slippage? Should the regulator be replaced when the alternator is replaced? I think my car has the small tin unit. Can and should I change the regulator to a newer electronic regulator?

 

115 amp is already pretty stout. I can't imagine needing more just for lamps. A couple big cooling fans and stereo amp might call for more.


Not entirely clear on what you're saying here. "...basic smooth pulley..." as opposed to.....what?


You should already have an electronic regulator inside the alternator. Mechanical regulators haven't been around for decades. Not sure what tin unit you are referring to.

Cheers
DD

 

With Doug here,

Mine all run that alternator and have twin Efans, Light wattage upping is maybe a few amps above standard, not going to create issues that I know of.

Being a 1989, and possibly a Marelli car, would have a "multi V" belt, and a flat tensioner pulley (memory here so stand by) that runs on the backside of that belt for tension.

I swapped that pulley for a standard "V": pulley to suit the crank pullet on my Pre Marelli cars. Never had an issue of any kind.

BUT

\\I ran a dedicated earth wire, alternator casing to chassis, AND, an addition +ve wire (6mm, google for your markets wire speak), from the Alt +ve TO the bulkhead battery post.
CLEANED, and CLEANED again EVERY earth point/strap/whatever I could find, even additional earth wires as I felt I needed.

SUPER bright Halogen headlamps, dash lights better, all sorts of things worked surprisingly better, called it beer o'clock.

That was 28+ years ago, still sweet as.

I have said this too many times:
The factory wiring/connectors were designed to last for 5 years AFTER warranty ran out, do the maths, we are all waaay past that time frame, so time to get down and dirty with the electrics.

 

Thank you for the information. I did not know how many amps the Bosch alternator put out until I purchased one. I just didn't want an alternator that put out 75 amps. I see that it puts out 115A and that should be fine. I also did notice the new unit had a regulator and did not think I needed the old regulator. The current alternator has one pulley the new unit has like 4 pulleys I don't know why so many. I did not know if all of the pulleys are smooth on the inside or if some have teeth on the inside of the pulley that match up with the teeth on the inside of the V belt to eliminate slippage like chain driven. I only know about electrical stuff not the mechanical that's why I send the car out that work.

 

I purchased a remanufactured OEM/OES Bosch alternator manufacturer part number31-00839OR DAC5224E. I thought the alternator would come with the pulley, It did not. What type, part # etc. should I get and where? I have been reading about a freewheel or a one way clutch pulley any suggestions? I would also like to replace the power cable from the alternator to wherever it goes to? Any part numbers, length of cable etc.?

 

Usually the old pulley is taken off the old alternator and put on the new alternator. The clutched type pulley are only needed on much higher amperage alternators where the rotating mass is greater. It's to prevent belt slipping when the alternator comes under a sudden load. You don't need that with the stock alternator.

 

OK, its taken a wh9ile to get my head ariynd whhat5 is going on, and I reckon old age is the reason.

BUT

Your OLD uit (75A) would have been a Lucas, with a single :V: pulley, using an 11A0850 V Belt to drive it.

The new is a Bosch, goodo, and requires a SINGLE V pulley. My time at Bosch, a v33334ylong 5im3 qgo, hqe QLL qlt34nqto4 whftw or 65

 

After many reads, and a few beers, here is my take on your situation.

The Old unit is a Lucas 75A, and the New is a Bosch 115A, goodo.

The Lucas ran a SINGLE V pulley using an 11A0850 V Belt to drive it, simple. You can retain this (I did on all mine).

You need a Bosch Single V pulley to suit the shaft diameter of the New unit. I seriously doubt the Lucas has the same shaft diameter. None of the swaps I did were that considerate.

ANY Bosch Service Agent will have a pulley, spacers, and nut.

WIRING

Make your own. Looms, and parts of, have been NLA for many, many years. The cable you mention travels FROM the +ve of the alternator, through that steel tube behind the exhaust manifold, and reattaches at the UPPER terminal post of the starter solenoid.

The old Lucas would have been Internal Regulated, as is the Bosch. That Reg thing you are talking about is what I suspect is the Load Dump Module, and is mostly removed, as it causes flat batteries as old age creeps in.

 

I'm not so sure about that, I think an 89 would have come from the factory with a 115A unit. If that is the case, then the pulley should swap over. I've not had a 5.3 XJS, but I had a 92 Series III V12 saloon with the 115A Bosch unit and it had a small multi rib belt - I think 4 ribs? It wasn't a V belt, like the other 3 belts.

 

AGREED.

BUT

Years are subjective, its a marketing thing as we all know.

Actual BUILD DATE is the best way, unless you are at Dealer level (as I was) then Vin # is the Bible.

IF, and that will only be anseered by the owner, it has 3 V belts, it will be a 75A and a 1988 build.

IF, however, it has a 4PK flat Alternator belt, then it is a larger Amp Alt than 75, and memory??? (hahaha) is 100ish, and would be a Bosch. That would then allow the pulley and spacers to be swapped to the 115, as Bosch used the same shaft size on all 90A and above Alternators of that era.

Memory once again, the 4PK came into use on the XJS with the Intro of Marelli, I think, and I am sure without splitting hairs. May 1989 is the Approx intro of that Marelli. Its is obviously Vin specific, but it matters not for now.

QUESTION

Is THIS CAR set up with ALL V belts, OR one Flat bet for the Alternator????, then we can clearly give the CORRECT info to get it sorted.

 

Something to keep in mind is that up to the late 90's a 115 Amp alternator wont produce anything near 115 amps at idle, more like 40 and maybe even less when hot. Around the late 90's / early 2000's a major leap in alternator technology happened. Tighter tollerances and improvements in the machines that do the windings allows for this next generation of alternators to produce as much as 80% of their rated power at idle. This also allows for smaller pulleys and more overall effiency.

The Ford 3G and GM CS series of alternator are amung this new generation and are popular to retrofit in to older vehcles. For exmaple I swapped in a Ford 3G alternator from a Ford Contour in to my Porsche 928 and I get more volts at idlle when fully loaded. Even though the Ford Alternator is rated for less amps it makes most of those amps near idle where I need it. The Bosche Alternator it replaced will only make its rated power at high RPM's when cold. The Ford Alternator also has a slipper clutch puley option which is extremely important to keep the belts on durng hgh perofmance driving.

At the present time I'm unaware of any drop in alternator upgrades for the XJS but I'm sure it's possible.

 

To some degree, or in at least some cases, these alternator upgrades can be a "cure looking for a disease".

I've had older Jags as daily drivers for 25 years and whatever alternator Jaguar installed always got the job done. Even my Series III XJ6, which had a somewhat pitiful alternator (60 amp or something like that) never failed me. It was adequate...although any add-on equipment would've surely been too much.

Cheers
DD

 

I have had slightly less success with the standard 75 amp alternators in my car. Basically it ate them every few years and I never had much confidence in them. I fitted a 115 amp when I did my rebuild and absolutely everything electrical worked better!

 

I fitted a CS alternator to my car, I put it where the air pump was. I had to put a spacer behind it as the air pump is wider, or at least the mounting bracket is. Changed the multi v pulley to a single v and it uses the factory size belt, so that will help in the future.

 

Very cool... And if you're ever on a road trip and need an alternator you'll be able to get one the same day. That's a big value add.

For me this is a big issue, I travel a lot wth my old cars great distances and often particpate in track events / race weekends. These are expensive and having a $1000+ race weekend ruined by a failed alt would be very disapponting. Case in point.... On my SBC swapped Jag the alt failed at my favorite event, the Empire Cup and a quick jaunt to Autozone got me back on the track quick so I only missed 1 session. And the Alt was covered under warranty. Cost me very little in time and money to get back in the mix. Similar drill with my Porsche 928, Alternator got wonky, low volts and kept tossing belts. In when a Ford 3G unit with slipper pulley than can handle quick RPM changes. No more problems out on track and should be easily found and replaced should it ever come to that.

 

I had the alternator replace by a local auto shop and I don't think they knew what they were doing. The man working on the car did not speak english and was trying to remove the alternator from the bottom of the car. I told the man who spoke english that the alternator had to come out the top. I gave him pictures and instructions as how to perform the work. I could not see how the electrical connections were made. I was told he unplug the old alternator and plugged the new one in and landed the ground. Should one brown #10 awg go to the battery from the large bolt on the alternator and the wire from the small bolt to the exciter on the starter solenoid and the only ground would be from the shell of the alternator. Any Ideas as to what they messed up on the installation? I had a large jumper box that would give me parallel batteries. I could watch the amperage drop as I was driving. I now have a new battery and a small hand held lithium 2000w jumper unit. I have not driven it yet except to get it home. I did change the lighting controls for my (4) 60w low-beams and the (4) 100w high-beams the high-beams only draw 5 amps. The new alternator is producing 13v. Is this normal or should the unit have a higher output?

 

13V where? 13V at the battery will not be enough. You need 13.8 to 14.4 to keep a battery topped up. Although we have a 12v system... a 12v batttery is really 12.8 volts and needs 13.8 to 14.4 to overcome its own internal resistance and take a full charge. Measure your Volts at the battery and at the big lead at the back of the alternator. If the Volts at the back of the alt are 13.8 to 14.4 then your alt is good. If you have a voltage drop at the battery of more than 0.2 volts then you have a wiring problem. Check grounds, battery cables etc.

New Alts like the CS130 and many others have a sense wire integrated into the car's wiring harness so the alt can know how many volts are getting to the battery and will use that value to raise it's output voltage to compensate.

 

I ran a few voltage tests. The voltage at the battery with nothing on in car the voltage was 12.9v, engine running just the interior and the parking lights on the voltage was 12.5v, revving the engine with just the interior and the parking lights on the voltage was 12.4, revving the engine with all of the lights on with high beam 12.2v. I did find a small white/red wire that came off the starting relay. I re installed it prior to the test. Is the next step for me to remove the pipes and equipment out of the way to get down to the alternator to review the terminations? there is a red tag on the alternator that says that the battery needs to be fully charged before using the alternator. If the battery was not charged would this cause a permanent issue?

 

I performed all the tests listed in the maintenance manuel and the alternator passed but I am still only getting 12.9V. Where does the alternator get the reference voltage from to know when to increase the output? I had a voltage regulator that was wired from the alternator to ground and it did not make a difference if it was connected or not. Most of the warning lights in the car don't work. I installed an indicating light in the circuit and the output did not change. I know the outside of the alternator is grounded but I am going to add a ground to the ground stud as labeled on the alternator as ground and see if that works.

I am also having issues with the four belts and only one 3 groove V pulley. I started looking at the alternator and other belts. The alternator belt is flat with parallel ribs and is on a seporat pulley from the main three V belt pulley bolted on the crankshaft. The forth pulley next to the crankshaft is being used for the alternator. Is that pulley actually the crankshaft damper? The pulley is loose, rotates (not at the same speed as the other pulleys), shakes from side to side and is noisy. What happened to my car? Should the car come with a 4 V slot pulley system on the crankshaft? Did the car come with a different serpentine belt system that the car would run on a 3 groove main crankshaft pulley? Where do I go from here? Attached are a few pictures.

 

BINGO.

Your flat (Aussie speak = PK) Drive pulley is knackered, as in the vulcanised rubber that attached it TO the crank pulley has died. Common.

NO IDEA what is available where you live for repairers. Down here, I had all mine re-vulcanised by a specific shop, now gone, sadly.

Until that is sorted, any measurements you take are a waste if time, flat out.

You need to remove the 4 bolts holding the "pack" to the front 0f the Damper, then the Big Bolt holding the Damper. DO NOT ALLOW THAT ENGINE TO ROTATE BACKWARDS, uness you have $$$ to fix it afterwards.

I AM NOT being rude, just truthful, so please dont take it wrongly. I have $$ from too many people who did not listen before computers and Forums, whoopee.

Once that drive ring is reattached, I reckon the beast be good to go. BUT, you gotta sort that dash light fiasco, some are required for charging.

Memory again???, that thing you call a regulator is a "Load Dump Module" and generally reeked more havoc than it solved. Mainly removed down here. The Alternator is INTERNALLY regulated.