I wrote many DIYs for E39 forum so I am very familiar with the
E39 setup.
I come from E39 (1998 528i), so we do cooling overhaul as preventive maintenance.
When I did that, I replaced most items in the cooling system. I wrote it up below for the
1998 528i:
ENTIRE COOLING SYSTEM REPLACEMENT Tips and Tricks (Very Long, Enjoy!)
Now, for the
2006 X6 3.0L MT with 113,000 miles, I am thinking out loud as preventive maintenance:
REPLACE:
1. Thermostat by Wahler, PN 11537509227 $55
2. WP by HEPU $62 (I have had HEPU in my E39 for 8 years, zero problems)
3. WP Pulley b/c this thing is plastic and usually cracks at 140K or so. It is cheap at $22.
4. Reservoir: BMW PN 17117573781, $76. This is b/c I saw some posts where people reported cracked reservoir at 125K.
CHECK AND REPLACE IF NECESSARY:
1. Fan Clutch
2. Fan Blade
3. Pulleys x 3 (incl AC system)
4. Belts x 2
KEEP:
1. Radiator because it rarely leaks before 150K.
I have had good success with Nissens radiator in my E39 for the last 8 years.
Anyone here has experience with Behr?
2. Radiator Hoses x2 because it rarely leaks before 150K.
Any opinions will be welcome!