Keeping coolant and transmission temps under control when towing in the summer heat

[alpha_omega]

Wow if we are only moving 1300cfm total then a cooling fan upgrade may be one of the best upgrades yet. @Geotrash i nominate you to change your before the Yellowstone trip lol

You have remember though, that’s the cfm listed for the motor only. How much more does the fan blade add (whether it’s 5, 7, 9 bladed) is as subjective as the total number, since there are so many factors that go into it. I’m not sure if the 1300cfm total is from the factory with everything assembled or not. It would make sense to see a number like that, because most big aftermarket fans advertising numbers in the 8k-10k range are only that high because they are listing the “full-flow” numbers - no obstructions whatsoever - however, down here in reality-land we have things like radiators, trans coolers, bumpers, baffles and grilles all playing a role in the amount of airflow being moved.

Nonetheless, if I remember correctly I’m pretty sure the number you want to shoot for on a V8 is closer to 2500 (minimum), so if that’s the case then we are asking for trouble by doing any kind of towing in temps above 75* while running stock fan kits. I’m sure glad you guys brought that topic up…now you’ve got me scratching my damn head again.

 

[Geotrash]

You have remember though, that’s the cfm listed for the motor only. How much more does the fan blade add (whether it’s 5, 7, 9 bladed) is as subjective as the total number, since there are so many factors that go into it. I’m not sure if the 1300cfm total is from the factory with everything assembled or not. It would make sense to see a number like that, because most big aftermarket fans advertising numbers in the 8k-10k range are only that high because they are listing the “full-flow” numbers - no obstructions whatsoever - however, down here in reality-land we have things like radiators, trans coolers, bumpers, baffles and grilles all playing a role in the amount of airflow being moved.

Nonetheless, if I remember correctly I’m pretty sure the number you want to shoot for on a V8 is closer to 2500 (minimum), so if that’s the case then we are asking for trouble by doing any kind of towing in temps above 75* while running stock fan kits. I’m sure glad you guys brought that topic up…now you’ve got me scratching my damn head again.

If it helps, the stock fan motors (including towing package, which I have), are 500W each. There is also an even heavier duty cooling package (K5L), which is rare, and apparently mine doesn't have, but it has 700W fan motors. Hence my plan to swap the fan motor and blade on the driver's side with a 700W motor, thanks to @thompsoj22 's comments early on.

 

[gooffeyguy]

If it helps, the stock fan motors (including towing package, which I have), are 500W each. There is also an even heavier duty cooling package (K5L), which is rare, and apparently mine doesn't have, but it has 700W fan motors. Hence my plan to swap the fan motor and blade on the driver's side with a 700W motor, thanks to @thompsoj22 's comments early on.

If it helps, the stock fan motors (including towing package, which I have), are 500W each. There is also an even heavier duty cooling package (K5L), which is rare, and apparently mine doesn't have, but it has 700W fan motors. Hence my plan to swap the fan motor and blade on the driver's side with a 700W motor, thanks to @thompsoj22 's comments early on.

Someone on here replaced their fan motors and blades with the 700w ones then started having electrical issues with the dash gauges or something whenever they would kick on. Think they replaced the alternator with a bigger amp one to fix it.

 

[Geotrash]

Someone on here replaced their fan motors and blades with the 700w ones then started having electrical issues with the dash gauges or something whenever they would kick on. Think they replaced the alternator with a bigger amp one to fix it.

Yup, that was @thompsoj22 on this thread.

 

[mikeyss]

I have the dual 700w setup and have had no electrical issues, but they are loud on high and even on low they can be heard standing in front of the Tahoe. Mine originally came with the 5/7 rimmed 500w, I quickly upgraded them shortly after buying my hoe.

 

[thompsoj22]

I have the dual 700w setup and have had no electrical issues, but they are loud on high and even on low they can be heard standing in front of the Tahoe. Mine originally came with the 5/7 rimmed 500w, I quickly upgraded them shortly after buying my hoe.

Short version? OE 5/7 500 watt, Upgraded to 700 watt motors which can draw up to 55amps when they cycle from low to high, Thats a 110 amp draw and at idle with the alt below it's rated output rpm the fans cycled to high, the lights dimmed and the bose stereo "blanked out" no display and no function. I recovered that anomaly with a bose input code entered by holding your finger in the bottom left corner of the screen. Anyway i decided to go with just one 700 watt 7 blade on the drivers side and staying with the 500/5 blade on the passenger side and i have had no further issues. Twin 700's move massive air but at idle in stop and go traffic they place an extreme burden on the alternator. This is just my experience, I am now running the DENSO 6860 220 amp alternator with overdrive pulley and all the big grounds/feed cables and can sit in stop and go extreme summer heat with ac on max and not have any issues.

 

[alpha_omega]

Short version? OE 5/7 500 watt, Upgraded to 700 watt motors which can draw up to 55amps when they cycle from low to high, Thats a 110 amp draw and at idle with the alt below it's rated output rpm the fans cycled to high, the lights dimmed and the bose stereo "blanked out" no display and no function. I recovered that anomaly with a bose input code entered by holding your finger in the bottom left corner of the screen. Anyway i decided to go with just one 700 watt 7 blade on the drivers side and staying with the 500/5 blade on the passenger side and i have had no further issues. Twin 700's move massive air but at idle in stop and go traffic they place an extreme burden on the alternator. This is just my experience, I am now running the DENSO 6860 220 amp alternator with overdrive pulley and all the big grounds/feed cables and can sit in stop and go extreme summer heat with ac on max and not have any issues.

Thank you for clearing up that last part as it was going to be my next question. A lot of the new guys out there think that “a bigger alternator will be better!”
No…not always. Sometimes that’s only the case if you match the pulley to it, and for someone who doesn’t change their own oil or couldn’t tell you where the water pump is located, I’m guessing they don’t have the tools for removing the harmonic balancer. Note to the new guys: don’t let this sway you! Use this as an excuse to learn new things and the reason why you need to buy new tools.

 

[thompsoj22]

Thank you for clearing up that last part as it was going to be my next question. A lot of the new guys out there think that “a bigger alternator will be better!”
No…not always. Sometimes that’s only the case if you match the pulley to it, and for someone who doesn’t change their own oil or couldn’t tell you where the water pump is located, I’m guessing they don’t have the tools for removing the harmonic balancer. Note to the new guys: don’t let this sway you! Use this as an excuse to learn new things and the reason why you need to buy new tools.

Actually it is the alternator pulley that I change, The OEM is 2.45 and the overdrive is 1.93. I advise this to just about anyone who wants more amps at idle. Will it wear the alt quicker? On paper yes as it spins faster but in reality the higher rpm increases the internal fan speed, Lowering the op temp of the critical parts, diodes/solid state internal voltage regulator and extending their service life. Our vehicles basically are always below 2000 rpm at cruising speed so you will never risk over speeding the alt for any extended duration.

 

[alpha_omega]

Actually it is the alternator pulley that I change, The OEM is 2.45 and the overdrive is 1.93. I advise this to just about anyone who wants more amps at idle. Will it wear the alt quicker? On paper yes as it spins faster but in reality the higher rpm increases the internal fan speed, Lowering the op temp of the critical parts, diodes/solid state internal voltage regulator and extending their service life. Our vehicles basically are always below 2000 rpm at cruising speed so you will never risk over speeding the alt for any extended duration.

Wait…so you’re buying a bigger (stronger) alternator, then changing the pulley that comes with it to an overdrive, but not changing the main drive pulley to an overdrive?

 

[Geotrash]

Wait…so you’re buying a bigger (stronger) alternator, then changing the pulley that comes with it to an overdrive, but not changing the main drive pulley to an overdrive?

I'm confused... why would you? If you're looking to spin the alternator faster, then you only need to change the alternator pulley to one with a smaller diameter (overdrive) to make that happen.