Auto gear box question...

[simpT5]

Hi all, I'm looking for your opinions on my auto gearbox's odd behaviour!

My car is a 99 ME7 P1 V70 T5 with a four speed AW50-42 gearbox.

It changes up and down through all of the gears smoothly and shows no signs of flaring or slipping between the gear changes whether it's hot or cold.

The problem seems to be when the torque converter locks up when I reach speeds of 50mph and above. If I'm travelling at any speed above 50mph (which I often do!) and I lift off the accelerator completely, the torque converter then disengages and the engine rpm's drop slightly - normal. However there is a delay of about 2 seconds when I reapply the throttle while the torque converter sorts itself out and locks up again, during this time the engine rpm's rise slightly like it's slipping? It does this even if I reapply the tiniest amount of throttle too.

Just to confuse me further, if I accelerate from say 30mph, when I get to 50 it locks up perfectly with no delay, it's only when I lift off and reapply the throttle.

It's been like this for about a year/10k miles now and hasn't got any worse in that time, it's just recently started to annoy me!

The ATF fluid level is spot on, is dark red in colour and doesn't smell burnt.

I've had 15 litres of Dexron 3 fluid sat in my garage for over 6 months with the intention of changing it, but I don't want to make this problem worse by introducing fresh clean ATF into the equation!


Any thoughts or suggestions will be gratefully received thanks.
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[AndysR]

Are you sure it hasn't always done that. The torque converter never locks up straight away if your traveling at road speeds of more than 50mph letting off the throttle and reapplying regardless of throttle pressure.

[merc85]

You usually know your own car, especially over time, i would give the transmission a Oil change.

Let's face it it should be change at some point.

[simpT5]

Are you sure it hasn't always done that. The torque converter never locks up straight away if your traveling at road speeds of more than 50mph letting off the throttle and reapplying regardless of throttle pressure.

I've had the car just over 3 years now and I'm pretty sure it didn't do it when I got it!

[tim15888]

Sounds like the torque converter is draining itself for some reason, then having to fill back up when you give it big licks. Not that clued up on auto's too be honest, but a torque converter works by holding oil under pressure inside, and pushing the fluid round with the vains on the engine side, which then the moving oil in turn pushes the vains on the gearbox side round... If it's emptieng of oil then it would possibly do what you are describing.

[AndysR]

I've had the car just over 3 years now and I'm pretty sure it didn't do it when I got it!

Perhaps I am not understanding what your saying then. When you reapply the accelerator it takes a few seconds for the torque converter to reengage? If that's right I've had mine 4 years and it's always done it, my brothers S70 does exactly the same thing also and has done for the 3 years he's had it.

[merc85]

Perhaps I am not understanding what your saying then. When you reapply the accelerator it takes a few seconds for the torque converter to reengage? If that's right I've had mine 4 years and it's always done it, my brothers S70 does exactly the same thing also and has done for the 3 years he's had it.

Mine also done the same andy, but only when the Box got hot.

[AndysR]

Mine also done the same andy, but only when the Box got hot.

Are you saying its a fault or an operating characteristic? What I'm describing is an operating characteristic not a fault it does it hot or cold ;)

[simpT5]

Perhaps I am not understanding what your saying then. When you reapply the accelerator it takes a few seconds for the torque converter to reengage? If that's right I've had mine 4 years and it's always done it, my brothers S70 does exactly the same thing also and has done for the 3 years he's had it.

Yeah it takes about 2 seconds or so to re-engage the torque converter and start accelerating again. I know this doesn't sound long but on a long twisty B road for example when you're constantly on and off the throttle it's quite annoying! Also with the revs rising slightly (about 500 rpm) for the 2 seconds whilst it engages, then dropping back when it does just doesn't sound right?

Hmmm you've got me thinking now lol!

[M-R-P]

Grabbing at ideas here... What mode is the gearbox in? (presuming it has the eco/sport modes)
Also, if the box mainly relies on mechanical feedback to an ecu, perhaps its just showing its age and responding to normal wear and tear. If its not slipping or flairing, I wouldnt worry but a tranny flush won't hurt.

[tim15888]

Sounds like the oil has gone thin and is draining from the torque converter then. If merc85's did it when hot, that supports the theory more, as ATF, like most oils gets less viscious when hot... Unusual fault though,

[AndysR]

Yeah it takes about 2 seconds or so to re-engage the torque converter and start accelerating again. I know this doesn't sound long but on a long twisty B road for example when you're constantly on and off the throttle it's quite annoying! Also with the revs rising slightly (about 500 rpm) for the 2 seconds whilst it engages, then dropping back when it does just doesn't sound right?

Hmmm you've got me thinking now lol!

Lol, well lock up is like another gear and usually accounts for around 400 ish rpm. Tbh it sounds normal to me perhaps you've never paid attention to it before and now you've noticed it you've become paranoid. Usually if something goes wrong with an auto the fluid condition is usually a good sign if something is up, also reverse gear will become clunky when selecting and general gear selection will become delayed.

[M-R-P]

Lol, well lock up is like another gear and usually accounts for around 400 ish rpm. Tbh it sounds normal to me perhaps you've never paid attention to it before and now you've noticed it you've become paranoid. Usually if something goes wrong with an auto the fluid condition is usually a good sign if something is up, also reverse gear will become clunky when selecting and general gear selection will become delayed.

Lol, mines a manual and acts like that! It's a LK tho...

[simpT5]

Thanks for the replies lads, most interesting!

Martin, my gearbox is the last of the 4 speed AW50-42's with just a 'W' button as opposed to the three sport/eco/winter buttons. I think it's supposed to be electronically adaptive or summat like that!

I like the theory of the oil losing it's viscosity when hot and draining out of the torque converter, makes sense I think!

I like to think I'm pretty handy with a spanner, infact I'm an auto electrician for a living but an auto box is one of the most complicated devices known to mankind!

Perhaps I'll change the atf (when the weather gets warmer!) and see what happens?

[tim15888]

Can't do it any harm lol. Alot of automajic cars you measure the oil levil with it running so the torque converter is full of oil... Not 100% sure about on these but are you measuring it runnung?

[M-R-P]

Thanks for the replies lads, most interesting!

Martin, my gearbox is the last of the 4 speed AW50-42's with just a 'W' button as opposed to the three sport/eco/winter buttons. I think it's supposed to be electronically adaptive or summat like that!

I like the theory of the oil losing it's viscosity when hot and draining out of the torque converter, makes sense I think!

I like to think I'm pretty handy with a spanner, infact I'm an auto electrician for a living but an auto box is one of the most complicated devices known to mankind!

Perhaps I'll change the atf (when the weather gets warmer!) and see what happens?
A flush won't hurt late. Empty, fill,.drive, empty, fill.drive etc. The more modern ones can be picky with new atf.

[simpT5]

Can't do it any harm lol. Alot of automajic cars you measure the oil levil with it running so the torque converter is full of oil... Not 100% sure about on these but are you measuring it runnung?

Yes, car on a level surface, atf up to temperature, cycle through each gear for a few seconds and back to park, engine still running and its bang on the max mark on the dipstick.

Maybe Andy is right about the paranoia theory!

I've read so many horror stories about cars being effectively scrapped through auto box faults, I'd hate that to happen to me as its taken me three years to get the car as I want it, both mechanically and aesthetically!

[M-R-P]

Yes, car on a level surface, atf up to temperature, cycle through each gear for a few seconds and back to park, engine still running and its bang on the max mark on the dipstick.

Maybe Andy is right about the paranoia theory!

I've read so many horror stories about cars being effectively scrapped through auto box faults, I'd hate that to happen to me as its taken me three years to get the car as I want it, both mechanically and aesthetically!

I know where you're coming.from there mate, have you seen my "is it worthit" thread?

[simpT5]

Yes I read your thread with great interest Martin!

Including the one where you took a chainsaw to your faulty dim in 'revenge of the skint'!!

Quality video that mate!

[tim15888]

Yes, car on a level surface, atf up to temperature, cycle through each gear for a few seconds and back to park, engine still running and its bang on the max mark on the dipstick.

Maybe Andy is right about the paranoia theory!

I've read so many horror stories about cars being effectively scrapped through auto box faults, I'd hate that to happen to me as its taken me three years to get the car as I want it, both mechanically and aesthetically!

What have you done to the car so far? Can't really tell from pics. Is it an ex-plod?

[AndysR]

Yes, car on a level surface, atf up to temperature, cycle through each gear for a few seconds and back to park, engine still running and its bang on the max mark on the dipstick.

Maybe Andy is right about the paranoia theory!

I've read so many horror stories about cars being effectively scrapped through auto box faults, I'd hate that to happen to me as its taken me three years to get the car as I want it, both mechanically and aesthetically!

Enough can't be said for the pros of regular oil changes preventative maintainence at its best if you ask me..

I am confident what you describe is normal, to the point that I'd film the behaviour of mine if it was taxed so you can compare with yours. I like the theory behind loss of fluid in the torque converter but if this was the case then when attempting to drive away after the car has been stood there would be a delay as pressure is built back up again, which i am guessing is not happening as you've not mentioned it.

[simpT5]

I have attached a quick video I made this morning...

http://s872.photobucket.com/albums/ab281/simpt5/?action=view&current=autobox2.mp4

[M-R-P]

Photobucket don't do videos very well mate, tends to just show a pic of the video...;)

[simpT5]

Photobucket don't do videos very well mate, tends to just show a pic of the video...;)

Stupid photobucket!!

Right, try again..........!!

[M-R-P]

Got it that time, don't own an auto myself but the father in law's lexus rx300 does that tho.

[Niles]

the 4th gear 'lock up' point is around 60mph, A quick guess is that when you are driving it around 60mph, the gearbox is switching lock up on, then you drop 'outside' the lock ups tolerance so the gearbox switches off lock up and costs you appx 500rpm.
Its basically a 5th gear (kind of) but its sensitive to the road speed on/off 'moment'.
I think is just that you seem to have a habit of hovering right on the lock up on off point. on...revs drop, back off the gas a bit, road speed drops...gearbox disengages lock up and engages 4th (no lock up) revs rise.
Kind of like cruising up a hill in 3rd, then you back off a bit coz your close to a car in front, the box will then drop to 4th thinking the 'pressure' is off. Then, you squeeze the car a bit and the car will drop back into 3rd, its basically right on the 'cross over point'.

Think that makes sense.

Either that or your torque converter is wearing. lol.

[simpT5]

the 4th gear 'lock up' point is around 60mph, A quick guess is that when you are driving it around 60mph, the gearbox is switching lock up on, then you drop 'outside' the lock ups tolerance so the gearbox switches off lock up and costs you appx 500rpm.
Its basically a 5th gear (kind of) but its sensitive to the road speed on/off 'moment'.
I think is just that you seem to have a habit of hovering right on the lock up on off point. on...revs drop, back off the gas a bit, road speed drops...gearbox disengages lock up and engages 4th (no lock up) revs rise.
Kind of like cruising up a hill in 3rd, then you back off a bit coz your close to a car in front, the box will then drop to 4th thinking the 'pressure' is off. Then, you squeeze the car a bit and the car will drop back into 3rd, its basically right on the 'cross over point'.

Think that makes sense.

Either that or your torque converter is wearing. lol.

Thanks for that, but it does it at any speed from 50mph up to...erm....70mph!

[wegal]

Change the atf fluid, dont just change it but flush the system. Then go and get the gearbox updates done, usually about £25 I think.

Problem should then go away. I flushed the ATF on mine recently as the gearbox was getting annoying, it was slow to respond and not all that smooth ( not bad, just not like new) changing the fluid solved all the problems, I didnt need the gearbox updates in the end.

Mine has done 75k on the same ATF. Changing it would be my first action.

[AndysR]

I have attached a quick video I made this morning...

http://s872.photobucket.com/albums/ab281/simpt5/?action=view&current=autobox2.mp4

Normal operation ;)

Change the fluid though as it's well worth doing on a regular basis despite what Volvo advise :)

[merc85]

Normal operation ;)

Change the fluid though as it's well worth doing on a regular basis despite what Volvo advise :)

Thats how my Box was after the fluid got hot despite a fluid change. But as andy says do a oil change to be on the safe side.

[simpT5]

Thanks allot for all your input lads, it's very much appreciated.

I'll change the atf when I get chance and report back!

What a great place this forum is, I don't usually post that often but I'm on here every day lurking about! It's nice that there are knowledgeable people willing to share it with others!

Cheers.

[M-R-P]

This forum and its members has helped me out no end. Even to the point of helping me decide not to scrap the big sweed. Some real diamonds here and I've been lucky enough to meet some of them too.
Keep us informed on your progress :).

[simpT5]

Bit of an update...

Well I finnaly got around to changing the atf this afternoon, I ended up getting just short of 4 litres from the sump alone, then disconnected the top hose to the atf cooler and managed to get another 8 - 10 litres pumped out before the fluid coming out was pretty much the same cherry red colour as the stuff I was putting in! I used near enough 15 litres in total.

The fluid I got out was black as hell, even though it didn't look too bad on the dipstick, I bet it's never been changed!

Anyway, I'm glad to report that my gearbox is now silky smooth and all the probs seem to have gone away :beer:

[AndysR]

Good news :)

[t5 pete]

Brilliant thread so is it deffinatly dextron 3 we need to use in our boxes as 3 of our t5s have never been changed so going to do it

[t5 pete]

this stuff if so ill order a few barrels
http://www.ebay.co.uk/itm/ATF-DIII-DEXRON-3-Automatic-Transmission-Fluid-20-ltr-/370282353380?pt=UK_Car_Accessories_Car_Care_Cleani ng&hash=item56368c52e4

[simpT5]

Brilliant thread so is it deffinatly dextron 3 we need to use in our boxes as 3 of our t5s have never been changed so going to do it

Yeah as long as your gearbox is an AW50-42 four speed then Dexron 3 is fine.

I can't stress what a difference it's made to the WHOLE operation of the gearbox, not just the probs I was having with the torque converter lockout.

It changes gear so much more smoothly now and kickdown is instant!

The one thing I forgot to mention before was I really did notice how much thinner the old black fluid I got out was, it was like pi$$ compared to the lovely thick cherry-ade that went in!

Defo a job worth doing, if only to prevent any problems in the future

[t5 pete]

brilliant cheers year i forgot to say there all phase 1 v70's