106 Auto not selecting gears correctly ALL SORTED... ALMOST!

Nuneatonrob · Post by **Nuneatonrob** » 09 Mar 2009, 11:29

A friend of mine has a 106 that he bought for his wife to learn to drive in. The car is a S reg XL Auto, and it's only covered 22000 miles from new. He got the car for a a song, due to having a fault with the auto box.

However, the auto box problem. It won't kick down, it won't select 1st or 2nd, it will only drive in what feels like 3rd gear. It has no power (engine runs fine though) and won't accelerate up hill very well at all.

It feels like the selector inside the car doesn't positively engage or 'select' properly?? It seems to slide between the positions with no click into any positon other than drive, and park, is this normal?

we have checked the fluid, and it's a dark colour almost black. We think there is a slight leak from somewhere on the transmition too.

Question is, what sort fo things can we try in order to make an attempt at rectifying the faults?

The car is in imaclulate original condition, and only covered 22000 from new, so we think that the fault with the box may not be to serious, as it's only done such low mileage.

Any clues or pointers would be very much appreciated.

Thanks folks,

Rob

Post by **CitroJim** » 09 Mar 2009, 13:02

Hi Rob,

Presumably this is a little electronically controlled "Auto Adaptive" 'box where the gear selection is controlled by electrovalves. Being only able to select Reverse and what seems like third gear only is very likely to be the gearbox going into "Limp Home" mode and working in its emergency hydraulic-only mode because the ECU has detected a fault somewhere.

Things to check is the ECU connector plug and the multi-way plug that connects the ECU to the gearbox proper. This connector often gets very mucky as ATF seeps around it. Also check the multi-pole switch that tells the ECU whet is selected on the gearstick (i.e PRND etc.). The ECU may also have gone Limping because of a failed input from an external sensor. A DIAG2000 session on the ECU will reveal all.

Another possibility, if it's a Siemens 'box is that the "old oil" warning has triggered. This'll put the whole thing into "Limp Home" and I understand can only be reset with a DIAG2000 or similar after giving it an oil change.

Don't worry overly about the oil colour. These boxes use ATF that is often straw-coloured when new and soon it looks dark due to clutch pack dust. I'd change it soonish though despite the low miles.

If you can get details of precisely what 'box is fitted, I might be able to find out a bit more for you.

Like you, I don't think it's too serious. The main thing is, it still drives and that is a good sign.

Nuneatonrob · Post by **Nuneatonrob** » 09 Mar 2009, 14:47

Hi jim,

Many thanks for the reply! I shall endeavour to obtain details of exactly which box the car has fitted and report back. Is there any particular way of telling what box this will have on it? any tell tail markings to look for or items on or around the box to look out for?

would it be best to get the chassis number and reg and call the dealer?

I have been looking up DIAG2000, and it would appear that you can download this to a laptop from the internet easily enough? Do you think this would be a good idea, or would it be just as cost effective to take it to a specialist \ 'Stealer' to have the ECU read?

I haven't got any cables to connect to the vehicles loom, so not sure how easy to come buy and expensive these are or not.

Thanks for the help so far. My bro in law and i don't want this 'little' problem to beat us...we are determined to fix it ourselves!!

Thanks again as ever.

Rob

Post by **CitroJim** » 09 Mar 2009, 17:02

Hi Rob,

No worries, happy to help

I reckon the best way to identify the 'box will be to look for its plate.

This is the plate from the ZF 4HP20 and I'd expect yours to have a similar one somewhere...

The problem with running DIAG2000 on a laptop is the need of the special interface pod to connect say, the laptop USB port to the diagnostic socket. That and the cables are incredibly expensive so for a one-off like this you may be best off going to see a Stealer. You may be able to be diagnosed by a Citroen Lexia so long as you tell the Lexia it's a Saxo you're looking at.

It's worth checking the ECU fuse and earths first off as the Limp Home mode will activate if the ECU is totally dead and all gearbox electrovalves are de-energised. If the 106 is anything like my V6, the ECU may not be in a very friendly place; mine is under the battery and you acn imagine what scope for damage exists with there

If the 'box turns out to be a good old hydro-mechanical one, the problems you have are likely to be a fault in the valve block. The 4HP14 as used in early Xantias suffer this issue and it's nothing more than a broken spring.

Good on you for wanting to fix it yourself

There's a bit of "black-art" scaremongering that goes on when it comes to autoboxes but they're not really as much rocket science as one may be led to believe

wheeler · Post by **wheeler** » 09 Mar 2009, 17:47

Should be an MB3 autobox fitted to the 106. Dont think they came with anything else.

Nuneatonrob · Post by **Nuneatonrob** » 09 Mar 2009, 22:49

Thanks again for the advice and input on this so far chaps.

I will try to get to the bottom of exactly which box it has, but wheeler suggests it's a BE3? I have no idea ether way yet.

I will however let you know as soon as I can, and share all my finds with the forum. Hopefully we can help others in future that way!!

Thanks again for all the help so far. It is as always, very very helpful of you.

Cheers,

Rob

wheeler · Post by **wheeler** » 09 Mar 2009, 22:59

Nuneatonrob wrote: I will try to get to the bottom of exactly which box it has, but wheeler suggests it's a BE3?

No I reckon it's an MB3

Post by **CitroJim** » 10 Mar 2009, 05:56

Hi Rob,

Here is a Wiring Diagram for the MB3.

It's a Renault gearbox

The gearbox is a pretty conventional auto adaptive electronic one. I can find very little on the 'net about it generally

Spares are available for it and it looks not unlike a miniture 4HP20 inside.

The wiring diagrams should help with the electronic side of things.

Post by **CitroJim** » 10 Mar 2009, 07:07

Rob,

Looking at the wiring diagram, the ECU (1630) takes inputs from the Vehicle Speed Sensor (1620) a pot (1636) which I suspect is attached to the throttle cable/butterfly, an RPM signal from the engine ECU and rev counter and a brake on signal from the tail lamp.

If any of these inputs are absent or in error, the 'box won't work. The pot (1636) along with engine and road speed will be the main input for kick-down.

The gear selector switch (1600) and its earth M1600 has to be worthy of close scrutiny. Not sure where it is on the 106 but on the 4HP20 it's on the gearbox itself, on the end of the selector cable. Yours might be down in the transmission tunnel and could be subject to getting covered in dirt and wet.

Hope that helps to give some clues Rob...

Nuneatonrob · Post by **Nuneatonrob** » 10 Mar 2009, 09:05

Sorry wheeler...I should open my eyes!!

MB3 box it is.

Many thanks for your help and advice so far Jim and everyone. It's certainly something to go on for now.

I will make sure I let you know how it goes in due course.

We have a 'garage' day planned for saturday, so along with my rear beam mounts, and this auto box problem, we should have an interesting day!!

Many thanks again.

Rob

Nuneatonrob · Post by **Nuneatonrob** » 14 Mar 2009, 22:32

Right then, had a look at the box this afternoon, and as for a plate which tells me exactly which box it is, I haven't been able to locate it. (So far)

It is the same box as a Saxo..there is one for sale on ebay which looks identical at the moment.

What I was able to determine today was that, the fluid level in the box was WAY over full...right up past the 2nd marking on the dipstick. Drained some fluid out to get it to the 'Max' mark and it still performed the same. e.g in 3rd gear..limp home mode.

The fluid was a very dark reddish colour and smelt a little bit like burn't plastic.

I think my Bro in law is gonna take it to a specialist to get the fault codes read. Checked all the connections for the ECU etc and it all seems fine.

It's very oily underneath, which looks to have come from the auto box...not sure if this is a bad sign or not, but it seems to not be too good to me, certainly considering it's only done 22k

I'll keep you posted of the the diag results.

Cheers,

Rob

Post by **CitroJim** » 15 Mar 2009, 09:37

Ahh, that sounds a bit serious Rob. The MB3 should be filled with Dexron 3 (as far as I can find out) and this should be red in coulour.

That you level was high, smelt burned and it was very high suggests there are troubles aplenty in the 'box itself.

The high level will be as a result of the torque convertor being drained. Level must only be checked with the engine running and warm to ensure the gearbox oil pump is running, keeping the torque convertor full.

A dark colour to the oil and a burned smell suggests the clutches have been slipping and burning, thus contaminating the oil.

One "nugget" I've discovered is that the oil cooler failes and allows the ATF and coolant to mix. Glycol in antifreeze is apparantly death to the gearbox clutches.

Does the coolant look a bit contaminated/oily?

Before fitting a new gearbox, replace the cooler as well.

Nuneatonrob · Post by **Nuneatonrob** » 15 Mar 2009, 20:01

Now you mention it Jim, we both wondered if the head gasket was at fault, as the coolant did indeed appear to be oily, and it also seems to be leaking from somewhere in a 'invisible' leak as the level has dropped since we topped it up just the other day.

Does it sound that the box is as good as scrap to you? (Obviously I appreciate you have not actually 'looked' at it)

I have recommended that my mate puts a bid in on the one on ebay at present. Even if it turns out his box is good, I don't think they are very readily available 2nd hand from what I have seen. I guess it could always be re-sold if not required.

Would you recommend replacing the box, then going from there? Not sure how best to proceed from here really.

I certainly want to open it up to see what is going on inside, I will let you know anything further we find out.

It will be fixed one way or another, because the car other than this is so clean, and original it deserves being put right.

Thanks again.

Rob

Post by **CitroJim** » 15 Mar 2009, 21:52

Now if you have oily coolant, an invisible coolant leak and rising oil in the autobox then it looks like the cooler has bid a fond goodnight Vienna

Now, the scrap box question is a hard one. I depends on how easily and cheaply a new one can be sourced. The 'box, as it stands, is far from scrap if you are happy to get stuck in to dismantling it and that is not as hard as it sounds. The issues with them are weight (they are surprisingly heavy) and the torque convertor.

All spares are available for them and it's likely you'll strip yours and not find that much wrong. Likely the clutch friction plates will need replacing, along with the oil filter and cooler. If the 'box has been contaminated, it's recommended that the torque convertor is replaced as well as it's nearly impossible to adequately flush them out and if the 'box has been contaminated with glycol it appears just a very tiny amount is enough to kill the clutches.

I'd be inclined to strip the 'box and have a look-see. You may find things more-or-less OK and then just give everything a really good clean, give the torque convertor a really good flush with fresh ATF (luckily it has no lock-up clutch to worry about), replace the filter and cooler and see how it goes. Luckily it uses Dex III ATF which is cheap (unlike the outrageous cost of the Esso LT for the 4HP20) so some can be used for flushing/cleaning.

I'd also be inclined, given it's stuck in third, to very carefully dismantle and inspect/clean the valve block. Do it in the house on very clean lint-free cloth and treat it like a precision instrument.

The MB3 is easier than some autoboxes to deal with as it uses all clutch packs and b=needs no adjustments. Those 'boxes that use brake bands need to be carefull adjusted after stripping.

Have a look at my website (click the www icon at the bottom of my post) and follow the links to my 4HP20 pages. Yours will come apart in a generally similar sort of way and a lot of the 4HP20 information will be generally applicable. I've still some pages to add but as this week I'm on training and will have time on my hands, I will get it done.

If you get another 'box from say eBay, I'd still be tempted to replace the cooler and give it a good once-over. Hopefully it will still contain sufficient oil to be able to determine if it's a good 'un. Try also to get the torque convertor that goes with it.

Good luck Rob and whatever happens, I guarantee you'll enjoy an autobox strip immensely!

Finally, have a look at Automatic Choice If you email them for a password to their on-line parts catalogue you can then see exploded diagrams and parts lists for every autobox ever made. Just remember yours is a Renault! The staff at Automatic Choice are very friendly and helpful and will send spares out mail-order no worries at all.

Nuneatonrob · Post by **Nuneatonrob** » 16 Mar 2009, 13:02

Jim that is fantastic info. Thank you very much indeed.

It does sound that there is an issue with the oil cooler leaking to me as you have mentioned. I think that is the likely area of concern in this particular situation.

I'll have a word with my mate, and give him the update. We are both in the opinion of just getting the box that is on ebay at the moment. All in it would be £180 if we use 'buy now'.

We think that this would be a safer bet and would facilitate getting the car on the road again sooner, being limited in knowledge on auto transmission overhaul. I do however want to strip the box that was in the car, and get a good understanding of how they work and maybe rebuild that box over time, and have a spare!

I'll have a good read of your web site and see what ideas I can gain from your experiences.

One final question Jim, if you don't mind. If we were to replace the box with a 2nd hand unit, would it still drive in limp home mode after fitting due to fault readings on the ECU, and would it be OK to drive the car to a specialist/stealer to have the codes cleared without damaging the replacement unit if it were required?

Thanks again Jim. I will update further in due course.

All the best,

Rob