1996 S6 Auto, not finding 3 and 4

[74rsman]

Hi
got an Urs6 Auto.
Its smooth on cold from neutral into D or R.
When a bit warm, it shunts. (bang).

Most worrying is it wont go for 3rd and 4th gear. It holds 2nd.
It did try 3rd but then just slipped for fun (no drive).
Any ideas? - changed the fluid recently, but Im new to the car so dont know
how it was prior.

Q: is the kickdown switch up under the dash or is it on the end of a long bar on the end
of the throttle cable, which seems to poke a vacuum pod stuck on the side of the block.
thoughts appreciated. thanks

[popdemonic]

you need a VAG-com and check if it throw you any faults on the gearbox menu.
the kick down switch is black box with rubber boot on the throttle cable being
mounted on the firewall.There're 2 small wires on it.i don't think you have
any problems with that switch though.I believe the clutch plate is on its
time or need a rebuild.how many miles on this car?You may try to check
the atf level if you lose some of it.also try to unscrew the drain plug and
see if there's some clutch pieces coming out.

[74rsman]

Hi
The ATF was very dark. No bits and pieces or metal in it though.
I'll vag com it for data and see what it says.
I wondered about the kickdown in case its stuck on..
I managed to get it to limp mode, which i think is supposed to default to 4th,
and it slipped, so I sense a rebuild. I think the clutches are gone.
ste

How many hrs labour (est) to get box out?
thanks

[UrS6 - IamS6]

Before you go too far.

You mentioned you're new to this car.

Why were you prompted to change the fluid ?

Was the box working before you started ?

And you changed the gearbox fluid.

Did you replace the filter ?

What fluid did you use to put into the gearbox ?

How did you measure how much new fluid to put into the gearbox ?

My information is not gospel, but it may be that you did not put enough fluid into the gearbox, is it the right fluid, and if you didn't replace the filter you should start at the beginning again, with a new filter, and new oem fluid (expensive).

My recollection is that there is a good thread on line or a good video detailing exactly how to change the fluid correctly, taking account of the temperature of the fluid and the getting the level correct, which one needs to do pretty accurately for the auto box to work correctly.

If it is done right, you should notice an improvement in it's changes, assuming it is not "really" broken.

Others on here will know more but this is a start before any misdiagnosis occurs and the box is taken out needlessly.

HTH.

[UrS6 - IamS6]

Sorry, just re-read your thread, some of my questions are superfluous, but the rest count.

[74rsman]

Hi
Thanks for the advice. I'm pursuing the fluid change and levels.
It had DexronIII I think? . It did have a new sump filter.

[74rsman]

Im just not convinced its broken (physically)
I feel its a hydraulic/fluid type issue -

Does anyone know definitively what type/brand ATF it should have so that should I get
it behaving I can end up with a system full of good stuff.

It wasnt flushed, it was drained at the sump and new stuff added which I know means the old and the new is likely merrily mixed.

[UrS6 - IamS6]

In this instance, as it is critical and will save the box / save the car, get the requisite amount of litres, (+1 litre for a spare / **** up / spillage), from the Dealer. More expensive, but worth it to do it right. The box needs the right fluid, and not just any old spurious ATF.

Definitely drain it and take off the sump of the gearbox and change the filter, changing the filter is essential for what you're trying to achieve, fresh oil fluid to make the box work correctly. You may need a sump gasket, if you do can't be big money.

Ten as mentioned work out the procedure for filling it, bringing it up to temperature, topping it up and check it again and then the final top up. Again get the precise procedure from youtube online or forums on line for refilling.

By doing it again and changing the filter this time, ironically the inside of the box should be pretty clean going forward. Cleaner than if you had got it right the first time.

It will be worth all the effort and expense in the end as the car will work, and it will work better than before.

Otherwise the car is scrap.

[74rsman]

Hi. Thanks for the advice.

Second change. Q. When i took the sump drain off there was no fluid in it ( engine off ) stared at it a bit and then opted to take the side filler plug out at which point woosh all the fluid fell out bottom and side. But it was a surprise that the fluid didnt come out with the bottom plug out only (thats normal?)

With the sump off and filter off i took a chance to check the solenoids, running them through the vagcom test program. They all clicked and responded and the pressure one cycled up and down so seemed ok. I cant check the valves or anything and im not taking the valve block off. So tomorrow we go for another fill up. Last time car on lift level. 3l in, engine idlie and gear to neutral filled as it drank at 36deg temp and cycled up and down the gears. So hopefully it will behave a bit better tomorrow..

Fingers crossed


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[74rsman]

reports are, still the same, no 3rd or 4th.
I'll have to vag com it, reset the codes and presume a fault might lie somewhere else..
Its got dexronIII good quality to the right audi standard. Im loath to change that for a 3rd fluid unless something magical is guaranteed.

I'll check out the TCM ecu, see if that looks healthy.
I might even resort to trying an alternate TCM (if I can find a spare).

Beyond that its a gearbox swap and hope the replacement is good
or a rebuild. Im not ready for the latter just yet.

Daft thing is, to touch the box im going to have to deal with the exhaust - it needs a new section from the front (inc cats) to the middle.
Other advise = 'scrap it' but I cant bring myself to do that. These things are rare old birds and I can't slaughter it because its giblets are all mixed up.

[macspring]

With the sump off and filter off i took a chance to check the solenoids, running them through the vagcom test program. They all clicked and responded and the pressure one cycled up and down so seemed ok. I can't check the valves or anything and I'm not taking the valve block off. So tomorrow we go for another fill up. Last time car on lift level. 3L in, engine idle and gear to neutral filled as it drank at 36deg temp and cycled up and down the gears. So hopefully it will behave a bit better tomorrow.

Fingers crossed.

Sent from my iPhone using Tapatalk

You've now exceeded my abilty and knowledge.

You are now on your own, unless someone else joins in.

[macspring]

These things are rare old birds and I can't slaughter it because its giblets are all mixed up.

You've got the right attitude towards the car, which unfortunately sometimes you need.
Hopefully someone assists you in getting to the bottom of it. Keep us all posted.

A known and genuinely good second hand box, (with a new filter and fluid), maybe your fall back position if all else fails.

You could also turn the problem into an opportunity and make it manual if you are feeling adventurous. Not at all a doddle though to be honest.

Blag some info from gearbox repair centres on the possible causes ?

Dave might advise what other cars this box is fitted to, including non Audi (?) which may be of assistance to know.

[74rsman]

Thanks for your help/advice. I might need that spare box..for now though I found the tech doc and diagnostics.
looking at the diagnostic diagrams and can see 3rd and 4th depend on the Mv3 solenoid turning off and the E clutch operating.

3rd needs MV1 on and 4th MV1 off.
I know MV1 works because it is used triggering 1st to second. I know MV2 works as its used for park and reverse.

So Im thinking. Maybe the MV3 Solenoid is turning off, but is not physically functioning functioning so pressure is not vented and valves are not moved (or vice versa in terms of fluid pressures and valves). OR - The MV3 solenoid is working fine and the problem lies further upstream.

When going for 3rd the car reports a dodgy value and unobtainable ratio. Looking on the chart its still in second, hence the signal/ration being flagged.
The computer thinks its in 3rd until it analyses speeds and sees it out of range.

Which leaves .. the 'E' clutch. which is only used for 3 and 4. and the shift valves for 2-3, 3-4 (assuming it might only be 2-3 is a problem but I'll check both)

The MV3 solenoid is turned on for reverse lock out when moving. And if its stuck then maybe it shouldnt let me get reverse when not moving, or this could be a red herring making me think MV3 is ok. It probably is..

So, its
1. drop the oil
2. remove the filter and base
3. remove the Mv3 solenoid and physically test/check for operation.
4. look to take off the valve side cover on the main body in situ.
- check the shift valves and springs in situ if possible.. - I think they have retaining clips to keep them in that require the valve body to be open to remove?

if Mv3 off triggers the E clutch, then Mv3 not turning off couldnt have resulted in the E clutch staying in place and burning out so Im hoping that the Solenoid is working and the next culprit in the line is the 2nd to 3rd shift valve being stuck...

It may well be that the shift valves are ok and the problem then lies either internal to the valve block or somewhere up in the gearbox.

Hoping I can get to the valve side covers easy enough and hoping a bit of inspecting and movement might clear anything stuck or broken.
I also expect logic to fail me at some point since my head hurts trying to work through the diagrams.

If attempt 3 doesnt solve things.

Attempt 4 could be valve body off entirely and sent away for test/fix?

Beyond that its big spanners time.

oh, ps I saw a fuzzy low res jpg that referred to a technical service bulletin mentioning 4th gear sometimes being neutral. I cant find the TSB anywhere, if anyone else knows what thats all about id appreciate the knowledge. cheers.

[macspring]

After that post I don't think you should be asking questions on here, we should be asking you.

Await a note of your further exploits in due course.

[74rsman]

no way, im prone to misinterpreting the tech diagrams and the logic :O)
Im also prone to not spending loads and presuming there is a simple fix somewhere! - so hopefully it will pay off.
I'd check the TCM box too..

Manual conversion would be fun but a bit more than I could carry out without it being off the road for a long long time.
Good idea though.