Some thoughts on Clutches & Actuators by our resident Guru Stu
6 CommentsFriday, 23 December 2016 | Stu
Affecting: C2 C3 Nemo 207 208 1007 Bipper
Dispelling a few myths about piloted manual gearboxes, or senso-drive transmission of Citroen C2 & C3.
Thinking back a few years, I had heard a few nightmare stories about auto gearboxes fitted to the new small Citroens, firstly it was tales of having to replace the gearbox, along with the clutch actuator and gearbox ecu, and its still got the same problem (the nature of which was never very clear). There were also many cases of the engine being impossible to start, in fact at Euro Car Care we dealt with quite a few cars which had been recovered to us with suspect battery problems, batteries had gone flat and then the car wouldn’t start- we would then do a diag check on the gearbox ecu to find a ‘power latch fault’ indicating some kind of voltage related fault causing the transmission to prohibit engine starting, may be because the transmission has somehow lost its programming. The battery would then be replaced and we would re-initialise the gearbox / clutch actuators and the car would start. We then started seeing a few actual clutch actuator failures, although they were not always attached to the car – they were brought to us by other garages who had replaced clutches or had recovered broken down cars and removed the clutch actuator as a possible reason for the car getting stuck in gear or impossible to engage a gear. We stripped down these actuators and found the mechanical adjuster inside the actuator had broken, these adjusters were repaired where possible and fitted back to the car. I have seen only one clutch actuator which had an electrical fault and this had a burnt out electric motor (which can be separated from the actuator), which we replaced from another failed actuator, and one case of input shaft bearing failure of the gearbox.
Around 2005 the software in the gearbox ecu was updated and this dealt with some driveability problems but mostly allowed the gearbox to remain in ‘auto’ mode after manually changing gear (the earlier system reverted to manual mode if the ‘flappy-paddles’ were used) This software can be installed in the earlier cars and this update sometimes seemed to cure clutch faults for a while.
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Fast forward to today – how do we approach suspect problems with senso-drive gearboxes? Well, in at least 90% of cases, the symptoms are caused by a worn out clutch. It is quite surprising how the life of the clutch plate can vary so greatly, we find worn out clutches at as little as 30,000 miles and I feel that an average clutch will last between 50,000 and 80,000 miles. Experience has taught us that interrogation of the customer and listening to the description of their symptoms is the best way to diagnose gearbox problems. It has also taught us that there is no temporary or cheap cure.
If an intermittent fault occurs which appears to be related to the clutch / gearbox, it will not be a one off, the fault will return unless something is replaced, and usually it will be both the clutch and the clutch actuator, unless you want your customer to lose faith in your competence. The actuator may be re-usable but it is impossible to know without re-fitting and testing for some extended time, the labour time for replacing the actuator alone is 2.5 hours which is included in the time for replacing the clutch so it makes sense to replace it while the clutch is replaced. It appears that the clutch actuator self adjusting mechanism will not always continue to work after it has adjusted to a worn clutch then re-set.
We always do a diagnostic check and record any fault codes and test drive the car before estimating the repair (its never safe to assume anything), you can sometimes get the feel that the clutch is not responding as it should and its worth listening to the transmission for clutch bearing / gearbox noise. The usual recommendation is to replace the clutch kit and clutch actuator and this is the only way to ensure the customer will not return with a subsequent fault and is the only way we can give a warranty on the clutch or actuator.
VERY occasionally the gearchange actuator can fail, I know of one which was faulty due to wear of the engagement motor brushes.