Hey guys, as you know I have a 1998 XJ8L that has performed flawlessly. Aside from the normal maintenance no issues until today. This morning I went to start the car and the battery just quit. I put the battery load tester on it and it was dead tossed in a second battery I have for it and checked to see if it was charging. It's doesn't seem like it is no matter at idle or a little higher it stays at 12v. It does go down a bit when you pop on the lights etc. I am assuming the Alt is shot but shouldn't the idiot come on?? It does not come on though. The light works because it does show when you put the key in the on position. Should I check anything else. I have an Alt for it I got but before I install it should I check anything else? Also when I do replace it what is the best way to get at it, it doesn't look like attacking it from the top is an option. First time I will be doing anything top it under the hood on this car.

 

John:
You are right, it does SEEM like an alternator, but there is a possibility that a power connection, or ground strap between the battery and the alternator has a bad connection and will give similar behavior. The problem with the idiot light is that the same circuitry that controls the alternator, the regulator, also lights the light. So...

 

I posted about the same issue a few weeks ago. No warning light, voltage at the battery 12.0V, never changing even with increased engine speed. Replaced the alternator and now have 14.0V right after start, typically 13.6-13.7 after a few minutes.

I have no idea why the warning light didn't illuminate with a voltage at the battery at 12.0V. I didn't get any responses to my post so I can't even point you there....

Replacing the alternator isn't bad...figure a couple of hours at the most. You have to remove the air filter box and the cooling fan pack to get to things. After you pull the alternator (two bolts and two electrical connections) push the bushing in the lower mount towards the rear of the car to make reassembly easier.

I found the best price on an alternator that was rebuilt by Denso on Amazon.

Good luck!

 

Thanks guys, I was up until 1am researching it. It looks like there are several suggestions on removing it and they are pretty much almost the same. Just not looking forward to doing it. Even though I am a trained mechanic I stopped doing it for a job back in the early 80s I really do not like doing auto work.

I ordered an new/remanufactured alternator thru a friend who runs a jobbers warehouse for $100.00 no core charge, That price can't be beat!! I did a little checking I couldn't find any issues with the wiring everything seem to be OK. A while ago I lost the splash shield under the bumper as well as the two cold air ducts. I pulled into a parking space at the mall and there was a piece of rebar sticking up out of the parking stops that grabbed the splash shield and damaged it. It was flopping around so I had to remove it. I saved the parts never got a chance to fix and replace them. I'll probably do that when I have the car up off the ground.

 

Mine gave no idiot light when the alternator was failing, even after the rear bearing started howling like a banshee. And replacing the alternator is NOT fun. i hope you have small hands. It's back in it's own little pocket between the engine and the frame rail, so everything is super hard to reach. I thought it would take me 30 minutes like every other alternator I've ever replaced. Oh no no no, it took 5 hours. If someone will give you a good price to do it I'd consider it. It's not fun at all.

Oh, and there's a little air duct that attaches to the back to funnel air to the bearings. Make sure it's there. Mine was missing, and why my rear bearings failed. The pocket the alternator is in is in a very hot location with basically no air flow. Without the little duct to get some air moving in there, it just cooks the alternator.

 

It sounds about as bad as it was to replace the water pump on my 97 Merc Sable. That was a job I thought would take about 30 to 40 mins. It took me almost 3 hours lots of curse words and thrown tools! LOL I got an offer to use my friend auto repair shop on the weekend. I just might take him up on it! I have the air ducts and the splash shield I'll have to do a little repair work on the splash shield but the rest is easy to put back in place. I took a good look at it yesterday I used one of those mirrors on a telescoping rod and there really is no room to work thankfully I do have fairly small hands. I am not looking forward to it truthfully. If my mechanic wasn't so far from me I think I would bring it to him. I have to check my after market warranty. I know it covers drive train and I think I added major electronics to it. I almost forgot I had the warranty I got it when I got the car and never had to use it, I actually thought is was over but I am no where near the mileage and I have almost a year and a half left on the time.

 

The Gods have smiled upon me! Just found out the Alternator is covered under my extended warranty! $100 deductible and towing included.

 

I have had many x308's and after learning from hard knocks from previous. EVERYONE gets a new alternator and a new battery right off the bat. the x308's are temperamental when it comes to voltage. Denso on Amazon.com for 185.00 delivered. also recommend the coolant temp sensor, gets rid of the 1638's

 

Nice! That will save you many curse words and skinned knuckles

 

changing an X308 alternator under a shade tree is by far the worst way to spend a day. Let a garage do it or have a buddy with a lift.

 

I do not understand why you would change a good alternator! If it fails change it, otherwise leave it alone. I know you say your experience dictates good results from replacing the alternator, but I have had no problems with mine. There are perfectly good ways to test an alternator and / or battery for voltage and current and those should lead a decision about what needs replacement.