Bump starting an auto

The only automatic you can bump start is an old mini/metro

So you didn't have the starting handle then? Or was this only fitted on really really old Range Rovers (used to have a 72' vintage one)

Swings and roundabouts really

Non possumus unless you disconnect the box first. :(

And then of course you could hand crank it with a heath robinson device made out of a ripe aubergine

No.

An auto box will be in neutral when the engine is stopped, as it needs the engine running to provide hydraulic pressure to operate the internal gubbins that select the gear.

no an auto can not be bump started. you should place the car in 4 low and have the gearbox in 1st gear when wheeling to get the maximum engine braking while descending.

Cheers, Jack

I thought that you were not supposed to tow automatics, or have I got this wrong??

Not as a general rule, as the gearbox will be damaged. You can tow then for a short distance at low speed and get away with it. With a landrover however, you can tow if you put the transfer box into neutral, as then the autobox will not be turning.

On or around Sun, 14 Sep 2003 15:45:41 GMT, AndWhyNot enlightened us thusly:

this is a multi-answer post...:-)

towing: most autos recommend less than 20 miles and less then 20 mph (some are "30 and 30"), without disconnecting transmission. On a Range Rover, you should be OK to put the main box in "P" and the transfer box in N; this will stop the main box rotating but still allow it to roll. For peace of mind, remove the propshafts, for long-distance towing.

Bump-starting: Most boxes won't. The Chrysler Torque-flite and the ZF4HP22 as fitted to various Range-Rovers fall into this category.

The AP/Lockheed 4-speeder as fitted to minis and metros had a bump-start valve which you could use to make it possible to bump-start it. (my father, among others, worked on the design of this box)

The Borg Warner type 35 (and, maybe, other BWs, but I don't know) which was fitted to various fords and rovers (Mk1 granada, transit, rover 2000, etc) has 2 oil pumps, one driven from the "engine" end, as normal, and one driven by the output shaft. These can't excatly be bump started, unless yo9u can push it up to about 25-30 mph. They can however be started down a steep enough hill or by towing - put the selector in D and tow up to about 25-30 mph, at which speed the rear pump will create enough pressure to engage the gears and torque converter.

By manually selecting second gear, it short circuits the aux pump feeding line pressure to tow start the car, according to my very dusty '68 manual ;)

how come I was able to bump start my old Mercedes g-wagon Mercedes even tell you how to do it as well you have to tow the car in neutral for 300 yards at approx. 20 miles a hour then put it into drive you will the fell the pressure in the box wind up until the engine turns over is this not the same principle for most auto boxes

On or around Sun, 14 Sep 2003 23:30:36 +0000 (UTC), "mboffroad" enlightened us thusly:

this sounds the same as the BW35 used to be. I don't know which 'box the G-wagen uses, but I'd hazard that it has a rear oil pump working off the output shaft.

I imagine it's a MB transmission, but it may not be.