By and large, the six-speed ZF automatic box as introduced in the 2001 E65 7 Series models has been a very good unit capable of putting up with high mileages. However, it does have faults and we’ve mentioned sticking valves in the Mechatronics valve block before. We’ve also mentioned the bridge seal that fits between the valve block and the main transmission casing before as well but it’s worth mentioning this again as it’s now becoming part of the gearbox service that many transmission specialists are offering. This rubber seal hardens with time and it can split, leading to pressure loss and thus the gearbox acting up with rough shifting and so on. Because the ECU is contained in the valve block and because there is a risk of it being damaged by static electricity, you must wear a ground strap when doing this job. But, the seal is about 30 or 40 quid and it takes two hours to drop the valve block, replace the seal and reassemble so it really is a no brainer to fit a new seal even if the gearbox was fine before.

Also, beware of anything other than a genuine ZF sump/filter kit. As many have found out, aftermarket plastic sump kits are not much use no matter how Germansounding the name and a friend of mine recently found out that after a week the sump was leaking (as was the mechatronics plug seal) and that the sump had actually distorted – no points for guessing which people’s republic that lot came from. So for a gearbox service – genuine ZF sump kit, new bridge seal and fresh oil at 100,000 miles or less and the good old sixspeed should be good for another 100,000.

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  • Started by Antonio Ghini
  • Saturday, 29 October 2016
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