2001XJWeekender

I did the mechanical to electric fan swap. It's in my build thread, and so far cooling is good.

Now the problem. With the engine runnin, and most everything else off (a/c, lights, radio, etc.) the Voltage meter says I'm at 13.52 Volts across the battery. It's a new (rebuilt) alternator that worked fine until the electric fan swap.

As the engine heats up to 210, the electric fan kicks in. I'll then kick on the A/C, and the belt starts to squeal at the alternator. I have the belt tight enough using the "twist it 90* method", and once before the alternator started smoking so I shut the Jeep off. Another time the Voltage dropped and the check gauges light came on.

So, is my alternator bad, underpowered, or something else?



K

jeepn_83

sounds as if the fan has a short or that the fan you have sucks to many amp or whatever u call it... i no that would effect it right off the batt if it took to much current

2001XJWeekender

Triple checked the wiring on the fan. No blown fuses, it turns on at an adequate temperature. I can hear the relay switch the fan on. It only seams to cause problems when I turn on more current loads.

The Alt is only about 6 months old, but I have a feeling it's starting to fail. It is an AutoZone 117Amp alternator, so I imagine it's got enough capacity for the electric fan and the other components.

I'll get it tested this weekend, as for now I'm kinda tired looking at the Jeep. Spent the last 3 nights working on this beast.

If this Alternator tests good, I may return it for the ZJ 136Amp Alt. Rumor has it there is a direct bolt in for the 4.0 somewhere.


K

TheJerm

hmm I can run both electric fans with my autozone alt and it does just fine. My voltmeter dips on the dash and may run alittle low but works fine. I never bothered to test the voltage while running tho.

2001XJWeekender

What amperage alt are you using?

My 117 amps should be plenty for the setup. The more I read and think on the matter, there has to be something with that alternator.


K

TheJerm

idk I just bought the stock replacement for my 95, I assume the 117a one. I would check the alt connections, battery connections and body grounds.

2001XJWeekender

Lat night before I left the garage I polished the battery posts and connectors with some steel wool. I'll do the same with the ground wires, and check the wiring from the alt to the battery. There was definitely some damage during last night's test drive as I can see some melted plastic at the back of the Alt.

I can understand a slight dip in volts when the fan starts, perhaps a max of 25 amps since it's a 30Amp fuse on a 30/40Amp relay that is still intact.

Would be nice to wrap this up, want to use the Jeep for a camping trip in 2 weeks.

Here are the specs on the fan.

Rated at 2200cfm

CFM
Pull-2400-2700
Push 2200-2500

Dimensions
16" x 16.9" x 3.2"

Amps
7.5-8.5

Volts
12

K

2001XJWeekender

Serpentine belt 810k6 2055mm is just too long. I swapped it for a 800k6 and tightened that biotch up so I could barely twist it. Now no squeal, and the voltage with full load of fans, lights, ac, etc stays above ~12 v idle, and 12.5v-13.7v while rpm move from 1000-2500.

Test drove and temps are staying 210-215 /w A/C, and it was close to 100*F today.


K

93gc40

Get a belt tension Gage $2-$5 at auto parts store. tension should be between 150 and 180 lbs. Twisting and flexing DOES NOT work with a serpentine belt.

TheJerm

I tighten it till it no long squeals, never had a problem. just takes alittle longer.