Charging Problems

[jerm1978]

I have a 85 CJ-7 but have a 304 out of an earlier model Jeep. When I bought the Jeep a few years back the previous owner had told me that the motor came out of a 79 CJ-7. Recently though I had some charging problems and when I couldn't find the problem, the mechanic swapped out a new alternator. It appeared to fix the problem only to find out a few weeks later it hadn't.

I've taken off the alternator and since tested it and it passed. However I believe it may be the wrong alternator because I remember the previous alternator having 2 slots on the pully. This new one only has one.

The problem is that once I tightend down the alternator the jeep runs fine and fully charges. However after 100-150 miles its starts charging less and less until the point it finally quits charging. Once I remove belt and replace and retighten everything goes back to normal.

I think it may have the wrong alternator and that maybe the alignment of the belt is just slightly off or that the alternator is slowly loosing down the adjustor.

Any other ideas?

Also, how can I determine exactly what year model motor I have? Reason I ask this is because even though the previous owner said it was a 79 motor, when I changed out the distributor cap recently, a '79 distributor didn't match, what matched was off a '72.

My battery also tested good.

 

[superj]

there should be some numbers on the block somewhere that are codes to get hte year of hte engine.

 

[SteelHeadz]

It sounds more like a loose or overheated connector rather than a failing alternator. The pulley drive belt grooves wont a difference in charging. If there was a mis-aligned pulley, it will squeel and prematurely wear out the v-belt if it doesnt throw it off the pulleys overall. A loose belt would cause a low charge output from the alternator if its slipping. Make sure you check the connections to the alternator for heat damage and or corrosion. Check the resistor wires going to the starter solenoid as well. One of those wires is responsible for charging. A typical symptom would be what you have described, charging okay until it gets exessively hot and it looses continuity.

 

[jerm1978]

It sounds more like a loose or overheated connector rather than a failing alternator. The pulley drive belt grooves wont a difference in charging. If there was a mis-aligned pulley, it will squeel and prematurely wear out the v-belt if it doesnt throw it off the pulleys overall. A loose belt would cause a low charge output from the alternator if its slipping. Make sure you check the connections to the alternator for heat damage and or corrosion. Check the resistor wires going to the starter solenoid as well. One of those wires is responsible for charging. A typical symptom would be what you have described, charging okay until it gets exessively hot and it looses continuity.

I agree it could be the connections because of heat damage, but how could this be fixed simply by pulling the alternator tight again and not messing with the connections at all?

 

[flatie46]

Are you saying the alt is loose after 100-150 miles? Or if you pull it off go check it, it checks ok and put it back it works ok? The battery cables in good shape?

 

[jerm1978]

Are you saying the alt is loose after 100-150 miles? Or if you pull it off go check it, it checks ok and put it back it works ok? The battery cables in good shape?

Its not noticably loose, but I just get in there, losen it, retighten it, inspect wires, then everything is fine again.

 

[SteelHeadz]

Theoretically speaking, if you loosen the alternator and re-tighten it , your moving the unit thus moving some wiring one way or the other. Check those wirings attached to the alternator and the harness that goes to the firewall bulkhead.

 

[jerm1978]

I'll try all the connections again tonight. Anybody know where the id number is on the motor? So I can check and validate what year model motor I have.