KD3NE

Here is the story ....

4.0 I6 Motor

Yesterday .... drove the jeep all over the place, over 300 miles. Several stops and starts no problems. We had two more trips to make, so off we went and it was getting dark so LIGHTS ON. Got to where we needed to be and parked the Jeep. Came back out to go home and NO START. Would not crank and acted like battery was down. I was 1/2 mile from home so I walked home to get another vehicle to come back and jump the dead one. When I got back I tried to start it before we jumped it and it started.

Today .... sort of the same scenario. After driving a while with lights on got to one stop and it would not start. Cranking was slow and lethargic. So finally we got it started and I drove it to a service center where they did the battery/charging system test.

Testing indicated ....
Battery GOOD
Alternator - Low Voltage Out

So I opted to buy and alternator and here is where the questions begin ....
90 Amp or 120 Amp ?

I figure 120 Amp would be better but IS THERE A DIFFERENCE?

They did not know so we looked at them both to compare. The body of the 120 is bigger and the pulley is narrower.

I looked at my Jeep and you could see the pulley on the Alternator was narrower, at least narrower than the pulley on the AC comp.

I figured the difference in pulley width was due to install clearances.

It made sense that the fatter alternator would have the narrower pull so the overall sizes would be the same.

DOES THAT MAKE SENSE? ( I hope so because I bought the 120 Amp unit. )


Now on to the $64,000 question .......

As most know, and as the alternator was marked, they are EXTERNALLY REGULATED. That is, there is no regulator on the alternator because it is an integral part of the ENGINE COMPUTER.

HOW CAN I TEST THE REGULATOR? ( is it possible - or something a Jeep dealer has tools to do?

I should add that everything else works fine.


THANKS !!!!!