Bedford CF Auto Box

[likaleica]

I'd be grateful for some informed advice please on the Vauxhall three speed automatic box in my 1983 Bedford CF camper. While towing a trailer with my classic car aboard, the box developed a fault - holding on before changing up the gears. It now changes 1st - 2nd @ 30 mph and 2rd - Top @ almost 50 mph. The box downshifts properly.
I'd just got the van back from a service by a rather hamfisted garage and I think they MAY have neglected to top up the transmission fluid - but as it's rather difficult on these to establish the correct dipstick reading I'm not sure. I must confess that in 3 years (though only about 10,000 miles of motoring) I've never cleaned the filters or completely changed the fluid. As I'm not familiar with auto boxes I decided to "leave well alone."
Have I fried the box and it needs to come out for repair - or is there another cheaper solution ?
Many thanks guys - Simon

[V8 FOU]

I would guess that the shift cable is stuck. If it has a vacuum modulator that could be faulty. I don't think you have a 'box fault, but it does need sorting. TBH I can't recall what 'box is fitted, then I could help a little more!

[mph1977]

i'm not auto expert either, but to echo the above what engine / box combo is fitted

is it the standard slant four petrol or has someone sneakily droped an ambulance spec 'Holden' 3.3 six cylinder in ?

[russell_ram]

Badly adjusted kick down cable. It's most probably adjusted too tight causing the box to 'hold' gears as if you are always doing full throttle accels.

[droopsnoot]

I might have a scan of the service manual for the GM 3-speed auto box, if it's any help?

[likaleica]

Many thanks for all the quick replies fellas ! It's the original slant 4 2.3 petrol engine and GM 3 speed auto box. The link to the manual would be warmly appreciated. Cheers

[droopsnoot]

I'll try and find it, hoping it's the right box.

[V8 FOU]

Ah,I thought it might be a GM box. That will have a vacuum modulator with a hose coming off the manifold somewhere. Most likely, though is the kick down cable - check it isn't stuck. Or disconnect it from the throttle linkage to see if the changes are better. They can sometimes stick inside the 'box, but that is really easy to do after removing the sump pan. Good luck!

[droopsnoot]

likaleica said:

Many thanks for all the quick replies fellas ! It's the original slant 4 2.3 petrol engine and GM 3 speed auto box. The link to the manual would be warmly appreciated. Cheers

In theory, this should be a link to the PDF but I've never shared anything on Google Drive before: https://drive.google.com/file/d/0Bxu8385TrnSeVjRvO...

[Flatinfourth]

Disconnect or back off the kickdown cable before you do anything else, it should change the gearbox characteristics immediately, and make it change up earlier.

[likaleica]

Thanks again guys. I tried to sort the kickdown cable but the Haynes manual instructions are so unclear I didn't succeed. Does anyone have a simple description of what I need to do please?

[Robin Hood]

Check the vacuum pipe that goes from the inlet manifold to the modulator on the gearbox. Has rubber connectors each end I think that can perish/split/come off.

[SV8Predator]

The very first thing you must do is check the transmission fluid level!

Then smell it.

[likaleica]

At long last the auto box is sorted and the likely problems were flagged up by many of you experts out there - so thanks very much for your help.
The vacuum pipe from the engine was split; there was a heavy transmission fluid leak (masked by a massive oil leak from the rear crankshaft oil seal)and these combined to make the box misbehave. I am hoping that now they're rectified I've done no lasting damage to the auto box - time will tell.
Thanks fellas.

[droopsnoot]

Rear crank oil seal is a "known issue" on the slant-four Vauxhall engine. There is a two-piece rubber seal that can be adapted to fit, and apparently solves most if not all problems - those I know that have fitted it have all reported good results.

[likaleica]

Unfortunately the original rope oil seal has just been renewed - but I'd be very interested in knowing what rubber seal you are referring to for next time !