• Welcome to the new NAXJA Forum! If your password does not work, please use "Forgot your password?" link on the log-in page. Please feel free to reach out to [email protected] if we can provide any assistance.

Alternator Cooling

taurus fan on low,

That's not OEM - and has a much higher amp draw. Are you exceeding the system's capacity when it switches to high in hot temps?
 
A Taurus fan isnt OEM????? oh crap!!!!!








Yes i was talking about the OEM fan that kicks on with the AC, or with a temperature above 210 (or whatever that temperature sensor in the radiator is rated at).

The taurus fan is ran by a switch... not a temperature sensor. Its on low all the time and i never have had the need to switch to high speed.
 
I noticed a slight decrease in out put during higher temps, but not enough to slow the blinkers at idle. Since you noted that the problem is eleviated when you raise the RPM slightly, have you considered a marginally smaller alternator pulley? I had one from a previous under drive pulley kit that was about 1/4" less in diameter that helped raise the alt RPM at idle. I drive about 12 miles a day and almost never see highway speeds, but even at higher RPM in lower gears, I haven't noticed any adverse effect.
 
A slightly smaller pulley will spin the alternator a little faster, which will move the power generation band lower in the rpm scale. The regulator will control the upper limit and you could get more power sooner.

A Taurus fan does consume more power than a Jeep OEM fan, and moves more air (the whole point.) Leaving it on full time - even at low - still adds to the overall load, especially at road speeds over 30mph, when the system pretty much disengages all of them. Air speed through the radiator is sufficient most of the time then.

Taurus alternators are high amp just to power the fans - what amp alternator is being used in this case? If the load is more than what the present alternator can support - which is what the symptoms indicate - then bigger is the answer.
 
Taurus amp fan draws: http://forums.corral.net/forums/showthread.php?t=989215

Scroll down. This poster sees a constant 22 amp draw at low speed. That's 25% of the capacity, or more, of a OEM Jeep alternator. Auto makers don't oversize them, it costs extra.

I see the same thing at work a lot - 1000 watts stereos on full blast cruising down the interstate when the Batt light on the dash starts blinking, or it won't start at a rest stop.
The owner has simply drained the battery because the system is undersized.
 
Sounds big enough to me. I've heard of San Jose, they have a good rep on the web.

I work the counter and answer phones - the company recently wrote about which to prioritize - and basically said do your best, but answer it in three rings if you can. Oh well.

Have you noticed the public's herd instinct to all call at the same time? Business meeting schedules sure seem to be similar, time of day, day of week, etc.

Hopefully you can get Rod at a quiet moment.
 
As an update..

Im pretty sure the problem is resolved. Sure additional alternator cooling would be great.. so i may look into that as an option in the future.

I remember when i first spoke with Rob about getting an alternator he said that a 140 amp is about the limit to keep the output at idle up enough to run everything. With the high load of the blower, ac, and ac compressor the alternator was not putting out enough current to keep up at a low rpm.

It turns out that my throttle body butterfly valve stop screw was set just a little to low by me when i first installed it (bored 63mm). I turned the stop screw to open the butterfly valve just a tad more at idle. This increased my idle to approx 800 rpms, but when the ac compressor kicks in, it drops to about 6-700. Before i changed the set screw the idle was much lower when the compressor kicked on. At such a low rpm the alternator just didnt have enough output.
 
Good idea!

As another update .. i still think that there is something wrong with the alternator i got. When i first start up the vehicle in the morning, voltage at the battery is 14.56. If i check it approx 5 minutes later, its down to about 14.3. Another 5 minutes .. something like 14.10. I have still yet to keep recording the voltage drop.. However, when i was doing these quick tests i noticed that if i watch my multimeter, the voltage was slowly droping. So like it would be between 14.32 and 14.33, and rock back and forth.. then drop to 14.31 and 14.32 and rock back and forth. It would keep droping .01 volts every 8 seconds or so. I mean i didnt accuratly time it or anything .. but you could tell it would keep dropping. I have yet to record the voltage at idle when i have the problem... but im really starting to suspect the alternator.
 
Last edited:
Muad'Dib said:
The cables are brand new from Jon (5-90) and the battery has never given me any issues. Always cranks over very easily.. even when its extremly hot out. Only when running and hot out does the voltage drop... To me all signs point to something with the alternator. But ill have the battery tested for shits and giggles.
Click to expand...

How are you measuring your voltage drop? With the stock dash voltmeter? I also have the new bigger complete cable set from Jon, and did notice a higher voltage drop w. the OEM dash voltmeter on my 91 MJ in higher temps when running full load; both electric fans, the H4 headlamps on, the fogs on, the A/C on, and the blower at HI. My alt is a 134A new unit from a V8 ZJ. But under full load, measuring the output charge across the battery always reads 13.5V min. no matter what the load or temp is with my DVM. Discussed this with Jon a bit, and he thought it might be the stock voltmeter sensing wiring (the original 10AWG cable from the alt to the PDC). On his suggestion, I removed this lead as it was creating a parallel path for the stock dash voltmeter sensing, and it helped the indication a lot, i.e. not indicating as severe voltage drop at full load at high temps on the meter. But I'm not concerned about it since my DVM indicates a correct charging voltage output no matter what the temp and/or system load.
 
Muad'Dib said:
The IP voltage gauge especially in a RENIX era rig is notorious for being inaccurate. I take its reading with a grain of salt. The voltage is measured at the battery with a fluke 77.
Click to expand...

Yep, this is true. But at least it helped my dash voltmeter read closer to true. It does sound like an alt problem. But I've never heard of heat soak (if that's what it is) affecting an alternator like that though. Batteries yes.
 
I bought mine off ebay.... but you can find them anywhere. Just make sure you get it for the alternator that you are using. Since I am RENIX, I have the Delco CS130. This is not the same pulley that is used on the Delco CS130D so beware of that also.

I want to say the stock CS130 pulley is 2-3/8" but I am not 100% sure.
 
Not too long ago, I installed a new ND alternator that bench tested at 190A. It has two fans as opposed to the stock XJ 90A alternator's single fan.

I "found" the fan at my local alternator rebuild shop. OK, he found it in the parts book. Physically, it is the same size as the ZJ alternator folks like to swap in. So... some trimming of the mounts was required. At idle, the alternator has been load tested to 180A.

Not to shabby that.

The alternator has a 54mm pulley on it. Same size as the stock 90A unit.
 
You must log in or register to reply here.

Similar threads

O
Routing ARB Air Lines to Rear Axle
Replies
10
Views
3K
XJlimitedx99
X
X
My brakes are crap
Replies
12
Views
3K
xjklmnop69
X
Root Moose
Cooling System Reset (2000 XJ)
Replies
1
Views
1K
Rob Mayercik
R
Bent
Contrary to what a lot of people believe...
Replies
3
Views
140
JohnX
JohnX
W
Newbie with an XJ
Replies
9
Views
248
Wander Motor
W
Back
Top