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Upgraded cooling fan

30K views 41 replies 13 participants last post by  0lllllll0 RPMEXTREME 
#1 ·
To start off I have an 08 JKU L96,6.0,6L80,using the Motech kit, tons and 40's. I was driving through Death Valley over spring break, the outside temp was 95. My engine usually runs between 200-210 range. This day it got up to 230 and I was just driving down the paved road. I have a CSF radiator with CSF 20psi cap. I have not had any radiator issues in the three years after my engine swap. I am looking to see if anyone has upgraded from the stock 3.8 fan to the Pentstar or Camaro fan and was it worth the $700. I have also heard that I may need a new TIPM to control the fan. Or am I better off adding a Poison Spyder hood vent for $180 to help expel some hot air.
 
#3 ·
Yes I am still using the stock 3.8 fan. The link you posted definitely is a better price point but also have the expense of buying a tuner. This is still in the price range of adding a Pentstar or Camaro fan that flow more CFM. I am trying to decide if dropping $700+ on a fan is worth it, or just try the vented hood and see if it works.
 
#8 ·
I checked last night and the fan comes on at 210. This is the correct running temp for the LS engines. When the fan come on the temp immediately dropped to 200. I did notice that my coolant in the reservoir was empty when cold which possibly created a air bubble in the system. I topped it off and ran up to temperature and then checked again this morning when cold. The coolant reservoir wasn't empty this time. Hopefully this was my problem. I think I may still add some hood vents though to help evacuate some heat.
 
#9 ·
I'm running the Pentastar fan with my L96 and have seen some extreme temps in Moab while crawling. I had some issues early on but after some good tuning with the fan settings it is back to normal operation.

This last trip to Moab, I flushed the system and went with Evan's waterless coolant. Wow, what a difference! I heard the fan twice, once on Cliff Hanger and once on Poison Spider but only for a minute then it was back to idle.
 
#10 ·
I have a 2008 JK with LS3 Crate motor and 6L80E transmission. I used an RPM Extreme conversion kit and did the work myself. I recently upgraded to the RPM upgraded HD radiator and Pendstar fan. It is like night and day to the previous upgraded radiator and stock fan setup. My temps varied widely from 200-215+ when the a/c was running in the summer and would go higher if I didn't turn off the a/c. I am firmly convinced the Pendstar fan with variable speed and HD radiator are a must in LS JK's. I did some air flow testing on my own and the Jeep grille opening is just too small and ineffectively designed, and air flow becomes very turbulent at speeds above 65mph and actually flows less air as speeds increase due to the aerodynamics of the Jeep front end which actually creates a reverse air flow current effect. And that is without a large front bumper or winch in place which further complicates and disrupts the airflow. I highly encourage anyone thinking of an LS conversion to talk to Jon at RPM Extreme before buying a conversion kit. He is extremely helpful and his follow-up service is tops. I have almost 40K on my JK with LS3 with zero problems following startup. He has a superior product in my opinion and when you need advice or help he is always available.
 
#23 ·
So is the pentestar fan waterproof? -ish? And has anyone figured out how to make it work without having to swap out stuff and get things reprogrammed?

I’m an electronics guy, but I really don’t want to play with things that “have” to be reliable if that makes sense.
 
#25 ·
The PCM can be reset to have the tipm control the pwm fan. Most of the 3.8 JK TIPMs have PWM capability built-in ('07 and some early '08 do not). AEV Procal can reprogram for PWM. I'd guess HP Tuners or another complete programming suite could do it too.

Sent from my LG-H910 using Tapatalk
 
#28 ·
I have a bully dog gt tuner, I’ll see if I can find the manual to see if it will do it.

Has anyone done this upgrade and had any issues? I’ve seen where some have stated replacing the TIPM deal for some reaso so I’m just curious. Guess I need to start calling around for fanpricing, thanks for the info guys.
 
#30 ·
Yeah, everything that I find is vague at best. I haven’t been able to obtain enough info to make an informed decision or which route to take. That deal from rpm to make the PWM fan play nice with the TIPM is like 400 alone, then the price of a fan, then add a tuner if my bullydog GT won’t work...
 
#31 ·
In some cases the Pentstar fan will not work in an early JK if the PCM has been modded. The AEV Procal will set the TIPM output to 10 Hz PWM, however we found a bug in communication between the PCM and TIPM inhibits the fan from running.

This may not be true in all cases and with the AEV update if it works your fan is not modulated so get ready for some noise.

For whatever reason Chrysler used a reverse PWM signal for the Pentstar fan making it more difficult to drive than a standard fan. Both the Pentstar fan and Camaro SS fans are sealed, brushless, 19"(stock JK 17"), electronically speed controlled, out-runner fan designs. While we support both we prefer the SS fan having conventional fan control and it seems quieter.

There is a new fan on the block, the JL fan. We installed a JL fan on a heavy JK with 40's. Temps in Vegas have been in the triple digits and fitting a JL fan to this particular JK brought impressive results. The JL fan is known for being LOUD, and it is at full speed to the point you need to turn iot off in the drive thru to talk; however, we have only seen the JL fan go to 69% in normal use and it was no louder than the SS or Pentstar.

The JL fan is less expensive than the SS or Pentstar fans, it is brushless, ESC controlled, outrunner.... but it is not sealed like the others. This may be why it cost less. We had a Gladiator here recently with HD cooling and there is a rumer it's fan is more powerful although it looked very much like the JL fan.

So far I'm very impressed with the JL fan it's cut the mustard in a heavy JK out here.

We can support all three of these fans if you have a GM ECM although we prefer to stay away from the Pentstar fan for various reasons. If you have a Hemi JK or a build with a non GM ECM we do have a stand alone fan controller that will run any of these fans with full modulation. The controller can accept CAN or analog inputs then put out the proper signal driver for several HZ's.
 
#32 ·
So the big question is, what is needed to get a JL fan working on an 07 then?
 
#33 ·
I'm running the AEV procal and 3.6 fan swap harness in my '08 JK, 392 hemi. First start last night, ran it for about 10 minutes. In the last three minutes, the engine coolant temperature reached 226 and held steady (18lb Stant radiator cap). The 3.6 fan did not come on. I thought the fan should have come on around 215 or so - is that correct?

I may have to go with one of those stand-alone fan control modules...
 
#34 ·
Rocky,

I used the stock 3.6 liter fan from my 2014 Wrangler. It ran on high only when it came on @ 212 - 215*. With C & R radiator it always stayed under 220* even climbing the steepest passes in Colorado. The fan sounded like a turbine when it ran and would quickly bring down the temp to 204* and shut off. The fan was a PWM brushless unit and operated from the ECU & the TIPM telling it when to operate.
 
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#35 · (Edited)
That's good info - thanks! Just talked to Robbie @MoTech - as he said above, I may have the glitch where the PCM isn't communicating properly with the TIPM, at least for the PWM fan control or ECT signal. Although, he also said that sometimes the Pentastar setups might come on at a higher temperature, more like ~230. He also said if the ac compressor pressure switch is disconnected, the open circuit should make the PWM fan come on high (my switch was disconnected, and the fan was not on...).

EDIT: OK so my AEV 3.6 fan conversion is working after all. I ran the engine again tonight - 20 minutes this time - and the fan turns on around 230F and off around 215-218F. I could definitely hear it, but it wasn't very loud so maybe its running on a slower speed? Another mystery: my ac pressure transducer was unplugged (still need to have new lines made up), but the fan only came on around 230F.
 
#36 ·
Rocky,

Yeah that sounds like the stock V6 fan temp setting. AEV had the temps for on off like I mentioned. Mine got up to 230* one time when I was pulling my friend through the sand at Wipe Out Hill do to a broken T - case @ 85* ambient. I was impressed how that fan pulled the temp down to 204*. The fan then ran most of the way out @ 215 - 218* . You could here that fan a block away and I had to get used to the fact that a V8 needs some fan speed most of the time on trails & idling. I wish it could have run say 50% and went to 100% when needed but it only ran 100%.
 
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#39 · (Edited)
Ok, so on my 07 the fan and shroud were damaged so this is why I'm asking.

I need to see if RPMExtreme is controlling the AC on the GM side, and then able to program the GM ECU for the JL fan then since I have their kit. Being sealed or not is not a worry as I don't ford rivers when offroading.

If I just wanted to make it complete stand alone, what controller do you recomend? I researched doing a Pentastar fan this way, but all the controllers I found had bad reviews and early/multi failures. Admittedly I didn't do an extensive search cause then this thread popped up.
 
#41 ·
I feel the best controller is the GM ECM, at least the most reliable; I don't like TIPM control.

The Pentstar fan has reverse PWM modulation and doesn't work well with the GM OS IMO. You can use it with a GM engine but I feel the JL and SS fans are a better choice.

I don't know any stand alone PWM controllers that use all the proper signals for a Pentstar fan, there may be one I am just not aware of it. If you want to properly integrate all the cooling functions like vehicle speed, trans temp, engine temp, AC pressure..... it's best to use the OE ECM to control the fan.

GM use to use a separate PWM fan controller(as did Chrysler) for many years. These modules interface between the PWM fan and the ECM/PCM. We ran a few on odd builds from Caravan's and Corvettes; however, now that all the electronics are built into the fan module it really cleans things up. You must be conscious to get a controller that matches your ECM/PCM and PWM fan, 10 Hz, 100 Hz, 128 Hz, polarity, lots of variables.

If at all possible use the GM ECM and stay away from stand alone controllers. The TIPM controlled fan would be my second choice if it is programmed properly.
 
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