840 Auto No Reverse

[hemibum]

HELP !!! Was stuck earlier today in a very icy, grassy parking spot, rear higher than front end.

Spent over 1 hour doing D -R D-R D-R eventually had to get towed out backwards. Now, reverse is'nt working. Thought originally that I'd maybe just overheated the auto fluid, but this evening it's still not engaging.

No message on the O.B.C, so, HELP anyone. Thanks.

[Ment-Al]

Don't park anywhere that you can't drive out forwards.

HTH

[hemibum]

Ment-Al said:

Don't park anywhere that you can't drive out forwards.

HTH

Your invaluable input is greatly appreciated

[Huff]

Check the type of autobox used, this is a known issue with the ZF 5hp30 IIRC.

What happens is that a small plastic check ball in the valve body waers, and eventually pops through a hole on the valve body where it shouldn't. Permanent fix is to drop the pan, pull the valvebody and replace the plastic check ball with a slightly bigger part. It should be quite an economical fix if you can find a good auto box centre local to you, and indeed can be DIYed - Google will find write-ups on several BMW forums for the E34s using this box (540 etc). HTH.

[XB70]

There is a place in Germany that one of the BMW forums was recommending for 7 series overhauls (I think it was the 7 series register). Anyways, worked out to be cheaper to bring the car over there and get the rebuild done and was to 'as new' condition.

[Talkwrench]

This is indeed a problem that can manifest itself on the earlier non-steptronic 5 speeds.
It is exactly as described - A plastic ball that wears & becomes misplaced.
ZF do a kit to repair the fault and it isnt particularly difficult for an auto specialist to sort out. Just make sure they put decent fluid in after carrying out the repair - not some cheap & nasty stuff that they buy for £3.75 per 100 ltrs!

[roofer]

Huff said:

Check the type of autobox used, this is a known issue with the ZF 5hp30 IIRC.

What happens is that a small plastic check ball in the valve body waers, and eventually pops through a hole on the valve body where it shouldn't. Permanent fix is to drop the pan, pull the valvebody and replace the plastic check ball with a slightly bigger part. It should be quite an economical fix if you can find a good auto box centre local to you, and indeed can be DIYed - Google will find write-ups on several BMW forums for the E34s using this box (540 etc). HTH.

Excellent info.

[sniff diesel]

hemibum said:

... eventually had to get towed out backwards. Now, reverse is'nt working.

Could towing it have done some damage?

[fluffnik]

XB70 said:

There is a place in Germany that one of the BMW forums was recommending for 7 series overhauls (I think it was the 7 series register). Anyways, worked out to be cheaper to bring the car over there and get the rebuild done and was to 'as new' condition.

Details here.

There's even a photo of the potentially offending ball:



Hope you get it sorted OK.

[hemibum]

Thanks guys for the input. Greatly appreciate it.. It is the 5 speed Steptronic and it was in R when being towed out backwards.

Trying to get hold of our local Autobox guy and see if he concurs with the "ball" diagnosis.

Meanwhile, really getting in to the mind set of planning each journey so that a reverse manuever isn't required.

[parksie]

Surely the position for a tow out would be Neutral??

[Huff]

If the engines not running it won't matter at all - autoboxes can't engage the clutches (and therefore, no gears enagage) without the hydraulic pump running - which is on the torque-converter end, engine-driven.

IOW with the engine not running you've got an entire gearbox full of neutrals

Edited by Huff on Thursday 11th December 16:33

[jagdpanther]

It could be something ridiculously small as suggested, I've got a similar problem with my E32 which won't engage forward gears, but reverse is fine...turns out it's a cable costing £30 from BMW themselves

Now to sell the Volvo and get the Bavarian Battlebh back on the road