S85 Vanos Pump Rebuild Kit
This is a complete parts pack for performing a VANOS drive gear update on early build 2006 M5 and M6s.
VANOS pumps manufactured after 9/05 were built with these updated parts, but production vehicles as late as 12/05. The drive gears have a longer tooth profile to address failures discovered on early builds. During this time, BMW also updated the oil pump drive chain tensioning system. This kit includes all the pieces necessary to update that as well. If you already have the oil pan off on a early build MY 2006 car, it is strongly recommended to verify the updated gears are installed.
The following parts are included:
- 1)VANOS Helical Drive Gear 11 36 7 838 018
- 1) VANOS Crankshaft Drive Sprocket 11 21 7 838 017
- 2) VANOS Drive gear crank dowel pins 11 23 1 263 911
- 1) VANOS Crank Drive Gear Screw 07 12 9 905 944
- 1) Oil Pump Chain Tensioner 11 41 7 837 576
- 1) Oil Pump Chain Tensioner Piston 11 41 7 837 578
- 1) Oil Pump Chain Tensioner Spring 11 41 7 835 445
- 1) Oil Pump Chain Tensioner Spring Pocket 11 41 7 835 444
- 1) Oil Pump Chain Tensioner Guide Bushing 11 41 7 837 577
- 1) Oil Pump Chain Lower Guide Rail 11 41 7 835 156
- 1) Crankshaft front radial seal 11 21 7 838 072
the springs, or lack of spring pressure, do not create the wear load on this part. The compression stroke on each revolution creates +1,500 psi on the pistons on the load side. This 1,500 psi load is transmitted to the load side of the rotating hub thru the pistons (on that side) to the race bearing to the needle bearing to the pump casting. The springs are there to "return" the piston to the home position and draw in oil for the next stroke....And contribute very little load when compared with the pressure stroke on the opposite side of the rotating hub.
It's this +1,500 psi piston pressure that keeps the pistons radially engaged in the bearing race.
Wear over time creates discontinuities (a widening can be seen in the pic below) in the track/grove in the bearing race. Once enough material is worn away the race stops rotating in the needle bearing (causing the race to accumulate wear in one region) and the race fractures (a bump in the race) at the thin location....causing the famous Vanos "tick"...and can be heard and felt in the "Tee" oil line above the water pump at the top of the engine. Secondary fractures occur and chunks of this race material, when failing, can either take out the sprocket and main oil pump drive chain assembly and/or wipe the helix drive gears attached to the crank shaft (driving the Vanos pump/sprocket assembly). Failing race material also creates a side load to the pistons and creates scoring to the piston cylinder....causing the pistons to bind and not return and not pump oil. In either case Vanos oil pressure is either reduced or lost causing a warning to display and the car to go into limp mode.