[thefys]

I am investigating how to add an additional transmission cooler to help the automatic transmission better dissipate heat when we tow with our 2006 X3 3.0i

So far we tow a 1,900 small T@B trailer
which should not present any problem for the X3 but I still think it would be beneficial to increase the cooling capacity of the transmission for longer life.



I have read some folks advise against additional transmission cooling, due to internal temperature switches and too low temperature as a result, but I am willing to bet that more cooling will help more than it will hurt in our case.

It would be great to hear from some folks that have gone down this path (and possibly upgraded). Reading many, many pages of posts here has not been that enlightening.

The one thread that I found really interesting in understanding tow packages was in the Dodge Durango forums which I will share here: Crap. Don't have the tow package. What to do?

It talks about added transmission coolers, bigger alternators, rear shocks that are auto leveling and of course electric brake controllers + a hitch. These factory upgrades upped the tow capacity of the Durango from 3,500lbs to 6,000 which blew me away.

I'd like to think something similar could be done for the X3. Have a look and let me know what you think !

[thefys]

I can answer this after two years of towing a 3,200lbs trailer and using ODB II realtime monitoring to look at the transmission oil temperature.

The short answer: The tranny oil got hotter when driving in the city (no towing) than when towing a trailer in the highway! I believe the transmission cooling systems are more than sufficient for this X3.

The numbers:

Drive Vancouver BC to Deception Pass WA (153.6 km - elevation gain negligible) April 2017
highest temperature 93°C - Ambient Temp 12°C

Climb Mt Seymour (elevation gain HUGE 3,068 ft) 101°C - Ambient Temp 5°C

Drive around town
- 95°C - AmbTemp 15°C
- South Burnaby to Bmo then to Granville island (45min traffic) 94°C (amb temp 10°C)


Porteau Cove to Vancouver( Nov 11, 2016 weekend)
- NO TOWING: ambient temp 11.5°C - at lions bay 77°C, at peak of Highway, westmount, 1km before exit 7 (westmount) , 81°C - at home 87°C
- TOWING: Ambient Temp 9.5-10.0 °C - at peak of Highway, westmount, 1km before exit 7 (westmount) , 95°C - at home 89, then 92°C at rear of driveway !°C

Nov 20
Returning from.Porteau Cove, TOWING Peak of Highway teal bridge, towing: 93°C, ambient 8.5°C

[CanadaeastKTM]

Nice post and very useful real world info.
Thanks for doing the monitoring and tracking this will be useful for others that plan to tow (I will be towing small 6X8 open trailer with 2 dirtbilkes around 1000lbs total on a regular basis).
Cheers!

[thefys]

Originally Posted by CanadaeastKTM

Nice post and very useful real world info.
Thanks for doing the monitoring and tracking this will be useful for others that plan to tow (I will be towing small 6X8 open trailer with 2 dirtbilkes around 1000lbs total on a regular basis).
Cheers!

Thank you. I hope someone else finds it useful as well. The X3 has been amazing for towing. We just got a 2013 2.8i X3 to tow as well. 8 gears should be very efficient !

[thefys]

Update - Dec 2022

Ditched that junker of an 2008 X3 for a 2013 X3(F25).
The F25 tows like a dream and is way more reliable IMO

[richardodn]

That ZF 8HP transmission is probably the first auto transmission that I actually like. I have it in an X3 35ix. I also have an 08 X3 3.0si and that 6 speed GM transmission is crap compared to the ZF.