1,2 TDI clutch/ gearbox problems

The overheat sensor failure is at first, in my experience (both our Lupo 3L's), an intermittent failure. Have you bypassed it? The evidence you offer strongly suggests that that is the problem.

If you haven't already, bypass the sensor, with a short length of insulated wire with a male spade connector at one end and a female spade connector at the other. If that doesn't solve the problem, the cause is likely to be the clutch or the clutch actuator. The system won't allow the engine to start if it senses that there is a problem with clutch dis-engagement. This might actually be the case (in which case the clutch guide sleeve might be the problem), or there is false indication of a clutch problem due to a failing potentiometer on the clutch actuator, which will require replacement of the actuator.

All the above of course assumes that you have a good accumulator and enough hydraulic oil!

RAB
 
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Rab, thanks, you were spot on. It is a mechanical clutch issue.

The clutch arm has a visible crack in it that has allowed the fork where the cable goes to bend 1cm in. So the clutch never actually releases properly.

Coincidentally, of the 3 Lupo 3Ls, 2 need the gearboxes removing. One to fix a serious diff like whirring and crunching noise, now this one to replace the arm. Is there a common Lupo box the *l one was derived from that I could buy to use for parts? I think my 5th gear is still OK.

RAB said:
The system won't allow the engine to start if it senses that there is a problem with clutch dis-engagement. This might actually be the case (in which case the clutch guide sleeve might be the problem), or there is false indication of a clutch problem due to a failing potentiometer on the clutch actuator, which will require replacement of the actuator.

RAB
Click to expand...
 
There is no common Lupo box that is a direct replacement, only a DSK (or possibly a FLE). The release shaft is used on other Lupo models, as are most of the gear-shifting components. Gears are a different matter and may be used on other models with the exception of 5th. Details here:

http://www.partscats.info/volkswage...232&bf=31130&hgug=311&ug=11&parent_id=1210614

The state of the gearbox oil is a good indication of gearbox condition. If it is heavily contaminated, a reconditioned box is probably the best option.

RAB
 
I am not expecting a direct replacement. A "properly" reconditioned box here costs more than my car did, plus you never really know what is inside. Someone from Hungary or Romania fitted a similar looking gearbox from a standard VW, and found that the car would not change into 5th properly because the ECU detected clutch slip due to lower ratios. Need to know what box they used. I can't find that post now. The idea would be to get a box like that one, many similar parts and the same clutch housing, worst case just fit my 5th gears. Best case is I just swap the better diff gear set over, and fit a new input shaft bearing in my existing box, and use the spare box clutch release arm on the other Lupo box. It will be interesting to see the old oil I agree. I think if I take my car apart without having a viable box on hand it will be a never ending project that ends in the car scrapped.

After the crunching started I was towed home in the car with the engine running, gearbox in N. All was quiet and smooth going home. Would the clutch be down or up when the car is idling in N I wonder? Just been looking at the car ignition on in N it seems that the clutch is disengaged!!!
 
There's no such thing as a standard Lupo box! There is something like 37 different gearbox codes for the Lupo! Worst still the drive shafts for the 3L are unique, although the differential in the 3L is used by many other gearbox variants.

Perhaps you need to visit the UK. I recently had a gearbox, reconditioned by (or via) VAG, fitted to my A2 by my local friendly VW agents for about £2,200, including labour and a new clutch.

If you change the ratios though, it will cause problems since the system constantly checks engine revs against the speed of a gearbox shaft. In neutral the clutch is always disengaged and is also disengaged when your foot is on the brake at low or no speed.

RAB
 
I took out the box with the broken clutch arm from one of the 3L's. On the Lupo 3L, you only need to remove the CV joint gaiter inner clips, and the shafts slid out with the triple joint on the end. For re-fitment I know from experience though, that generic Gaiter clips can foul the oil sump on the (longer) right hand side driveshaft, and that a special tool is needed to fit original clips. No need to drain the box or work hard to remove the drive shafts. The box came out under the car without removing the subframe, only the top mount (and hydraulic system). First off was the pump, the connector valves in the pump body stop fluid leaking from the pump unit. The clutch arm part number is specific to the engine type in ETKA. So I just ordered a new clutch arm. The 3L I am working on had done 160K km from new, and had a reconditioned box already. The gearbox code started with what looked like FF under the silver paint. FFU gearbox I assume. I bought the car about 3 years ago, with about 120K km, and was told at the time it recently had a new transmission fitted. The release arm had been painted black, and the new one was plated. This makes me think that the release arm may not have been replaced during reconditioning. It could have done 400k km+ for all I know before it failed. That always worries me about reconditioned units. The new arm went in easily, and I need to finish off installation tomorrow. Either the arm was fatigued, or the hydraulic unit somehow applied too much force and bent it to breaking point. The gearbox code was on the top of the clutch housing, difficult to see when installed. So for the other 3L, I will remove the box first and look inside to see what parts I need before trying to guess which gearbox type might have the used parts I need to build a good box.
 
The DSK, FLE & FFU are all very similar. The FLE is least similar of the three but has the same ratios as the other two. Some parts are not interchangeable. The part that monitors the clutch is the potentiometer in the clutch actuator; failure of this is the most likely cause, apart from fatigue.

RAB
 
When the arm first cracked (about 1cm), I readjusted the clutch, and the car started, but I could see with the car idling in neutral, the clutch arm "quivering", hunting slightly. I will fit a different clutch slave cylinder to be safe. Thanks for that tip! That could well be the root cause.
 
I put the car back together with a new slave clutch cylinder, and clutch release arm. The clutch seems mechanically and electrically OK. Engine starts in neutral only, but the gangsteller (gear change robot) is changing gear all the time in an uncontrolled way, and the indicator relay is clicking like crazy, no indicators flashing. Prior to all this, there had been some intermittent random clicking, months before, from the indicator relay. If you remove the indicator relay, the clicking obviously stops. If I remove the connectors from the gangsteller robot, the clicking stops. Is there any connection between the indicators and the gearbox system wiring?
 
No link between indicators and gearbox surely? You obviously have a wiring issue. Have you tried changing the indicator relay? A scan might show the fault. If you can only start in neutral, there is still an issue with the clutch, either the actuator or the release bearing.

RAB
 
I saw from Tuneko Youtube video that it would be wise to change the gear linkage/operating rod. The rod (085142471) seems relatively inexpensive but the ball studs (085142285 and 6N0711608A) seem really expensive for what they are. If I change/get the rod changed, should I change the ball studs and/or the sealing plates (6N0711965) at the same time? Is the rod relatively easy to change at the same time with gearbox basic settings?
 
Why do you need to change any parts? Don't follow a Youtube video blindly! The main point of changing the rod would be wear in the ball ends. If there is wear in the ends, there is likely to be wear in the studs also. I would change all parts (if necessary). It should be a straightforward job but do not adjust the length of the rod.

RAB
 
RAB said:
Why do you need to change any parts? Don't follow a Youtube video blindly! The main point of changing the rod would be wear in the ball ends. If there is wear in the ends, there is likely to be wear in the studs also. I would change all parts (if necessary). It should be a straightforward job but do not adjust the length of the rod.

RAB
Click to expand...
Thanks for the info. I just want some extra peace of mind. I ordered all of the parts so the official Audi service can change them when they do the service and basic settings.

BTW, how does one go about changing the hydraulic fluid? Is there a drain plug somewhere?
 
There's no drain plug for the hydraulic oil. You should only need to drain it if it is contaminated, usually with water. There's no other way than to dismantle the system.

RAB
 
Started to have gearbox problems this week. At first it took like 5 seconds to switch in R or D after cold starting. Yesterday dissapeared R 4ht and 5th gears. Engine goes idle after trying to switch. Hydraulic oil level is ok. Pump starts to run after 2 gear changes. Can a defective hydraulic accumulator be the reason for these problems?
 
A faulty accumulator is the most likely reason. The accumulator contains nitrogen over a diaphragm which over time leaks away, leaving little or no gas to compress. To change, disconnect the plug connection to the hydraulic unit, unscrew the accumulator with an open ended spanner (24mm I think) and replace, check the hydraulic oil level (VW hydraulic steering oil) so that the level is within the rectangle on the reservoir. Then reconnect the plug.

RAB
 
I'll post a little report, maybe it helps someone. Ordered new accumulator and VAG COM cable. Accumulator change didn't solve problem, but a new one wouldn't hurt. VCDS showed 00263 & 00789 (problem in g239 or g240 potentiometer) fault codes. Went under the car and started to check gear actuator, problem was simple - loose bolt (see picture). It's the part where lower end of linkage is mounted to. Did basic setting and cleared fault codes. Have driven some time without any problems.
Also found out that linkage show some minimal play. Gonna change it. Gan someone please give me the part number?
IMAG0858.sized.jpg
 
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