Citroen C8 auto box creeps/slow changes

[PeteC8]

Hi, after many years owning BX's and a Xantia, I have just bought a 2004 C8 2.0HDi "full house" auto with a genuine 79000 on clock.
Being completely new to auto boxes, I note that the car creeps forward/ reverse at a walking pace unless the brake is on. Is this normal? Also, the car seems slow to accelerate ( again, new to auto's so no reference point!). In park or neutral, the accelerator seems sluggish. No flashing lights to indicate problems. Your esteemed thoughts would be much appreciated!

Many thanks, Pete.

[GiveMeABreak]

It is normal for 'creeping' when in 'Drive'. Unlike a manual vehicle with a clutch, automatics use a torque converter to transfer power from the engine to the gearbox, but unlike a manual vehicle, the torque converter is never fully disconnected, so this is why you get the creeping.

You will also find that engine speed is often limited in neutral or park to prevent damage. Remember the car is 18 years old now, and you won't know what condition the gear box is in. The first thing I would do is get the gearbox oil changed as this can have an effect on the actual performance of the gearbox. The oil over time can become burnt and can contain small particles of material from the clutch packs. Parts that can wear in an Auto box include clutch plates, clutch bands, bearings, bushings and seals for example.

Despite the 'sealed for life' claims, automatic gearbox oil can become contaminated from the parts I mentioned above over time. It can become contaminated and dirty so is recommended to change it at anywhere around the 30k - 50k mile mark to keep the transmission it in good condition. If the transmission is slipping on acceleration or there is considerable hesitation or has a burning or toast smell then there is a problem with the box that needs looking at.

There is a special procedure required when changing the oil. Torque converters can't be fully drained, and on the AM6 gearbox you can only change about 3 of the 7 litres at a time as 4 litres remain in the torque converter, so when undertaking a transmission change, it usually involves several oil changes over a couple of months use to get to as near a full change as you can. Similarly with an AL4 gearbox the total capacity is only 6 litres, so again you can only change 3 litres at a time. The transmission oil temperature has to be 60 °C when changing to ensure as many of the contaminants are suspended in the oil when it is drained. A professional level diagnostic tool is also required to reset the oil level counter in the gearbox ECU each time an oil change is undertaken.

So you may want to delegate this to a dealer or garage with experience of undertaking automatic transmission oil changes if you don't have experience of doing this yourself.

[PeteC8]

Thanks, Marc. I will organise some oil. I'm very familiar with mechanics generally (multiple BX's do that to you), but never gone near an auto yet. How do I know what gearbox I have fitted?

[GiveMeABreak]

Pop your VIN up, It'll either be an AM6 or AL4

[PeteC8]

Thanks for all your efforts, Marc, here is my vin VF7**************[VIN obfuscated, can be read by forum staff] I think, taken from label inside drivers door. Haven't got the V5 yet to confirm it.

[myglaren]

Your VIN should also be at the bottom of the windscreen in a small window.
Nearside normally.

[GiveMeABreak]

Ok, so confirmed as the 4 speed AL4 Automatic Box Pete.

[PeteC8]

Thanks!