I was having charging issues with my old alternator and decided to replace it. My old alternator's label was completely rubbed off, but it was definitely a Bosh type. The alternator was replaced about a week a go. Today, my car had no power when accelerating and my intake sounded loud. It wasn't for sure it was the intake, but the sound came from that area. The same mechanic that replaced the alternator (I got a 90amp) came over to check it out and suspected I can a clogged catalytic converter. If it's in park and I rev it up, the sound cannot be heard. Only when it's in gear. After a bit he mentioned the sound is coming from the alternator, and suggested I get it replaced and start from there. I got the alternator from eBay, and it looked pretty banged up, but was much cheaper at $50.

I called a couple of Jaguar dealers and spoke to the parts department to see if with the VIN I can find out exactly how many amps I need. Usual options are 90 and 115 amps. Rarely do I see 80amps. The label on the old alternator is the only marking it has, and its completely rubbed off. The dealer suggested there might be a stamp somewhere in the body, but didn't know for sure, and that the VIN does not provide information as to which amp to use. It says I need a Bosh, cause Lucas was used before, but the amperage is not specified. So which one would I need? Or is there a certain way to find out?

Is it really a big jump between 90 and 115? Assuming I need 90, and I install a 115, would I have serious overcharge issues? Or any other issues?

 

89 VDP and you need the 115amp alternator.

 

No, the alternator will only supply what the car requires at the time.

For $50 you might have a rebuildable core or a good alternator.
You can assume nothing about its condition.
A rebuilt unit would have been a better choice.

While out on the bench, at the very least:

check for a burnt stator winding, if the windings are blackened or the insulation coating flakes off, it is ready for the graveyard

feel for bad bearings by rotating the rotor
disassemble and:
check the brushes for length
check the commutator condition
check the diodes
check the stator windings
check the rotor windings

then take it to a parts place and get it bench tested for free.

Only install if you know for certain that the alternator is good.
All of this is better than putting in a dud.

And why isn't the mechanic replacing a week old alternator? Unless of course he did not supply the alternator. Then, you are on your own.

 

I can get a new one, well, a re manufactured one for 114.00 for a 115amp. Which is weird because the 90amp is cheaper. Or is it weird?

So am gonna order the 115 today from AutoZone.

Yea, I'm on my own since I supplied the alternator (from eBay), that's what I get for trying to save money. I really hope that's the issue from that noise I mentioned. Cause if it's this, AND the catalytic converter as initially suspected, I'm gonna be one unhappy camper.

 

Some people recommend that when you buy a rebuild that you get them to test it for you right then and there before you leave. Bad units right out of the box are not unknown.

You might also consider having them test your existing alternator before buying.

 

The 115amp turned out too large to fit in the space allotted. Additionally, some of the brackets did not align. So I ordered the 90amp. At this point, I can only hope that the alternator I got from eBay was a crappy one and didn't even charge as it should. While it was out today I turned it and made it spin by hand it sounded grainy, not smooth. Is it suppose to sound smooth?

The 90amp don't get here until Thurs afternoon, so I'll see what happens then.

 

Shouldn't make any sound at all.

The grainy sound is probably your bearings. You should be able to feel it while rotating the pulley. Since you had it out, why didn't you take it to autozone for testing?

If a 115amp was originally offered for your specific vehicle/engine combination, then the unit you got was probably misidentified by the rebuilder.

 

That's the thing, all auto parts stores offer an 80, 90, and 115 amp for my year and model. I had to tell them which one was the right one. I was not able to identify the amperage from the original one because the chrome label had completely rubbed off. I then bought a 90 amp on eBay, based on some asking around and research online. That one turned out bad, or so the mechanic says. He is convinced the sound it's making is coming from there. Though is a bad alternator enough to make the engine bog down when accelerating?

When I decided to replace that bad eBay alternator, I wanted to get the amperage correct this time instead of guessing. I called 6 nearby Jaguar dealer to be precise. One was not able to answer as my VIN did not specify amperage, only brand, which is a Bosh not Lucas (actually all dealer said this). Two others could not give me an answer either for sure, but suggested a 90amp. The other three told me go with the 115amp since it was a Vanden Plas. Made sense to me what they stated, since it has A/C and it's a Vanden Plas, the best choice would be the one with the higher amperage. That ended up not fitting. Too large, and doesn't align.

So now, I am to wait to install the 90 amp when it gets here and hopefully solve the issue. If not, then I guess the problem will be the second thing the mechanic suspected, a clogged catalytic converter.

To expand a bit more: That day that the bad eBay alternator was removed, I accidentally left the parking lights on. Which remained on for no more than 3 hrs. When I went to lock my car 3 hrs later, the battery was dead. Like dead, dead. So I suspect the alternator was bad from the beginning.

Sorry if I'm typing up essays here.