Auto Box seems to be slipping.

[Budgie]

I'm after some ideas about a problem with the auto box in a 3.9 V8 Disco I acquired a few months ago.
It drives fine for about an hour, then when you try to accelerate it feels like the clutches are slipping. I thought it was only in top but today it was doing it in 1st as well.
As soon as you easy off then it feels like in engages and becomes smooth but a little touch on the throttle and it's back vibrating again.  :?

I've got to give it an oil & filter change as I don't know when it was last done. The service record says the last service was July 2003 which could be true as it's only done 8000 miles since then!!  :shock:
I had to put about a litre of ATF in the box when I checked all the levels, and got a good load of that on the steering shaft.  #-o
So, I was just wondering if anyone else has had a similar problem and what the solution was?
I'm going to give Ashcrofts a phone shortly to see if they can come up with anything. I hope it's nothing serious as a recon box is half the price I payed for the whole Disco!!

Oh, one other thing - when the engine is warm and you restart after stopping for a while, the engine revs up to 1800-1900 rpm before slowly returning to normal tickover.
I've removed, cleaned and replaced the stepper motor, which has made it a little better, but it there anything else I can look at to solve this issue?

Cheers,
Budgie.

[beast5680]

sounds very like a torque converter problem if its doing it in all the gears :?

[Budgie]

That thought had crossed my mind.
 I'm hoping that a couple of oil changes will do the trick as it's fine before it's really warmed up which could be the ATF breaking down if it's been in there since 2003.  [-o<

[andycwb]

I'd get the ATF changed twice before worrying about expensive options.  An awful lot stays in the torque convertor during a change.

[Budgie]

That's the initial plan Andy, first oil change will be with a new filter kit, then run it for a couple of weeks and change just the oil. I may even do a third if it seems to be making a difference.

[smith335]

can you change the filter on a zf box,with out having to remove the chassis cross member that sits under the gear box?

as i need to do mine ,but dont fancy trying to get the nuts undone on the cross member.

[Range Rover Blues]

I don't think you can, no.  I couldn't.

I've also used http://cgi.ebay.co.uk/Automatic-Gearbox-Transmission-STOP-SLIP_W0QQitemZ230021467781QQihZ013QQcategoryZ28641QQcmdZViewItem
this stuff before.

[smith335]

did it work?

how long did it take to see the results?

ttfn

[Range Rover Blues]

I put it in a Capri that had @issues@ the results should be imeadiate and yes it worked.

I've also used it in the LSE to keep the temp down, which it does.  LSE works hard though as it's my towcar.

[smith335]

Thanks,i might just give it a go...

[Budgie]

I'll keep it in mind as well, cheers for that.  

I changed the oil today and the old ATF was a nice light brown colour, rather than red. I've taken it on a 20 mile drive today and it seems better, although another oil change and the filters should do it even more good.
I'll keep you posted.  

[Range Rover Blues]

With a bit of luck the slipping will be down to low hydraulic pressure rather than bad wear then.

[Budgie]

With any luck yes.  :D
It's not missed a beat since the oil change but then again I've only done about 60 miles.
I'll give it a couple of week before the next change, I've e be getting on with for now.
I've still got to sort out why it revs to nearly 2000 rpm when I start it when warm, before slowly going back to normal tickover. Stepper motor's been cleaned and I even tried a spare with not difference. I read an old post about the ECU revving he engine to make up for a weak battery but the Optima I have fitted is fully charged, any other ideas?

[chuggaman]

was the spare stepper a new or old one ?




mike

[Budgie]

It was a used one that was off a spare motor I have but that was cleaned and tested before fitting.
I didn't fancy buying a new one just to test it, have you seen the price of them!  :shock:

[Landynuts]

can you change the filter on a zf box,with out having to remove the chassis cross member that sits under the gear box?

I managed it eventually but it took a lot of swearing and skinned knuckles!

[Range Rover Blues]

It was a used one that was off a spare motor I have but that was cleaned and tested before fitting.
I didn't fancy buying a new one just to test it, have you seen the price of them!  :shock:

No, but I can imagine.  TBH I'd say if that's all that's wrong with it I'd stop worrying.  The ECU does rev the engine if the cranking voltage falls, perhaps a look at the earth wiring around the car, chassis/body or somthing, perhaps the voltage at the ECU drops during cranking even though you've got a good battery.

[Budgie]

I had another look around the engine bay today and found one of the temp' sensor connectors, under the thermostat housing, wasn't connected to the sensor. So it's reconnected now and I'll see what it's like when I go to work tonight.  
What I'm thinking is: If the temp' sensor feeds the water temp to the ECU then the ECU maybe thinks the engine is cold as it can't read the sensor, thus it's putting extra fuel in (or closing the stepper motor) to bring the tick-over up - as a choke would do. Does that sound about right?  :?

[Range Rover Blues]

On the V8 IIRC one is for the temp guage and the other for the ECU, but the one directly on the thermostat elbow is for the airconn fans, that one has 2 blades on it and is by far the biggest of the 3.

[Budgie]

I'm not sure what it feeds but I could only see two of them (there is a third that screws into the thermostat housing itself) but it was the larger one of the two in the inlet manifold and has a brown connector.

Edit: I re-read your post and it's not the aircon fan sensor.  

[remmy7]

Hi all'

Sorry to hijack this thread but it seems to fit my current problem. Its been a while since I last posted because all has been going well with my disco(approx 10000m trouble free). The problematic missfire was cured when I fitted a set of new plugs (the type with the four electrodes) if this was all that it was I could have saved myself a fortune.

Anyway my current problem is that my 2000 model v8 auto also seems to have a slipping box. It only manifests itself when I start up in the morning and for a few seconds doesnt move. Once it has moved a few hundred yards or so all seems fine although I am not convinced it is now transmitting the power as it should. The whole thing is due a service ( although I am using the best part of half a litre of engine oil per 1000m since the engine rebuild). My question is the same as above. Will a change of ATF (it hasnt been done for at least the 40000m I have owned it) cure the apparent slip as when using it off road I really miss the instant response ( still can beat the manual box for this)

Regards Remmy7

[Budgie]

Well it seems to have done the trick in my case as I've not had the problem since the first oil change.
At 40k I would think that the ATF would be past it's best and a filter change would also help alot.  

[remmy7]

Hi Budgie

Thanks for that, I shall get onto it soonest, I presume it is a fairly simple task and there is not a shock in store (please note I said presume)

Thanks again Remmy7

[Budgie]

Just changing the ATF is straight forward. Drain the old stuff out and refill through the dip-stick shaft. Measure the amount that you drain out and refill nearly the same amount. Then start the engine, put it in "N" and check the level, topping up as required.

Changing the filter is a little more involved as you need to remove the sump on the auto box to get at it. On my 300 series Disco it's easier to remove the crossmember under the auto box to allow access to the sump.

[Range Rover Blues]

What Budgie said.  TBH I'd advice the filter though, it may well prove to be worth the effort.

Budgie, that plug sounds like the EFi water temp sensor.  Try unplugging the ECU for 5 minutes, it resets the faults, then try it for a few days.

[Budgie]

I'll give the ECU a go and see what happens.
It's been a lot better since I plugged it back in though but it still revs to around 1800 rpm on initial start from warm but it comes back down to tickover much faster now.
I also found 3 of the exhaust manifold bolts on the passenger side were loose (I wondered where the exhaust ticking noise was coming from :roll: ) and that seems to have made it a bit better too.
It doesn't seem to run away so much going down hill as it used too and it seems to give a more even engine breaking as well, it used too serge a bit when it got to around 1500 rpm.
I still need to change the leads, dizzy cap & rotor arm, do the auto box filter and another ATF change. Then it's on to the transfer box, axles and swivels for an oil change.

I think I'll also check the base tickover (by plugging the hose to the stepper motor) as the tamper-proof cap is missing and I know the previous own had problems with high tickover as well. So mybe someone has been in there playing!

[Range Rover Blues]

A lot of less weel informed tinkerers have messed about with the base idle screw thinking it controls the running idle speed, so probably best to DIY.