Autobox holding in gear for too long when cold

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TerryG
Posts: 6757
Joined: Wed Jan 05, 2011 1:54 pm
Location: East Midlands

Autobox holding in gear for too long when cold

#1 Post by TerryG »

The auto box on my Range Rover is holding in gear for too long when it's cold. After it has warmed up all is well. If i let off the throttle it changes up and if i accelerate again in the new gear it is fine, foot flat to the floor and it kicks down as it should but it doesn't want to change up by itself.
This is getting slightly irritating but isn't stopping me using the car every day.
It had new fluid (but not a filter change as the x-member is stuck) about 10,000 miles ago and this is getting progressivly worse.
Any ideas where to start?
Understeer: when you hit the wall with the front of the car.
Oversteer: when you hit the wall with the back of the car.
Horsepower: how fast you hit the wall.
Torque: how far you take the wall with you.
harvey
Posts: 286
Joined: Wed Jan 05, 2011 4:47 pm

Re: Autobox holding in gear for too long when cold

#2 Post by harvey »

I assume this is a ZF box, and they're not exactly something I know a lot about, but I think I'd go for the filter first. Cold oil will be thicker so have more difficulty being sucked through the filter. IIRC you have to jack the chassis rails apart to get the crossmember out. After that if it kicksdown when needed you would have to assume that is working correctly, whether it's cable or vacuum operated so it might be a sticky governor not building up pressure to trigger the changes. But tbh you'd be better off finding someone who knows a bit more about them that I do. (Which shouldn't be too hard....)
Currently over 35 years worth of fixing 35 boxes.
Hoping to reach 65 years worth of fixing 65 boxes.
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Dave M
Posts: 9
Joined: Thu Mar 03, 2011 7:37 pm
Location: Crewe, Cheshire

Re: Autobox holding in gear for too long when cold

#3 Post by Dave M »

^^ WHS ^^

Almost certainly a faulty govenor valve. It can be caused by lack of pressure because of a dirty filter but, occasionally changing the fluid and/or filter will actually make it worse as the fresh fluid will dislodge tiny particles of dirt which then get caught up in other parts of the box. The govenor can be removed, cleaned and new seals fitted with the box in situ - but the transfer box has to come out though. Any good autobox specialst should be able to sort it for you - or give these guys a call for some more advice http://www.ashcroft-transmissions.co.uk
David

1977 Vauxhall VX2300 saloon (GLS spoiler, getrag 5-speed box, Bydenstein head)
1976 Vauxhall Sporthatch (in pieces in the garage!)
2003 MG ZT-T (my daily driver)
1993 Mini Cooper 1.3 Spi (my wife's summer runabout)
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TerryG
Posts: 6757
Joined: Wed Jan 05, 2011 1:54 pm
Location: East Midlands

Re: Autobox holding in gear for too long when cold

#4 Post by TerryG »

Nuts, never mind i have an HP24 sitting in the garage so i'll try a new filter and another change of fluid then give up and change it, however as i have at minimum blown another head gasket and as the engine will currently not turn over further investigation will have to wait until they are fixed and the car is once again mobile.
Thanks for the suggestions guys :)
Understeer: when you hit the wall with the front of the car.
Oversteer: when you hit the wall with the back of the car.
Horsepower: how fast you hit the wall.
Torque: how far you take the wall with you.
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