C4 auto in C5
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Thread: C4 auto in C5

  1. #1
    Join Date
    Jul 2015

    Default C4 auto in C5

    Hi. I have a 2002 Hdi C5 with a very bad auto transmission with 300,000km.
    I've bought a 2007 C4 Picasso petrol auto with 110,000km.
    Is it possible to swap the trans over to the C5 Hdi.
    I know the shift points might be different.
    Would it physically bolt on.
    At the moment I have to put it in gear and wait about 10 minutes for it to heat up before getting any drive.
    Then of course even when it moves I soon get a Auto fault.
    I did enjoy the car for a short period before the auto started playing up.
    The Picasso is a stat write off if anyone wants some parts.
    Front left damage.
    I thought about changing the whole power plant but thought it might be even more trouble.
    Thanks Gary


  2. #2
    Fellow Frogger
    Join Date
    Jan 2004


    Changing the whole drivetrain is not really an option, so suggest you drop that outright.
    I'm sure you could bolt the Picasso AL4 into the HDI, but I suspect the torque converter will different between the two models and, without actually checking, I'd guess the gearboxes have different crown wheel and pinion ratios. You can look it up both cars in Citroen Service by VIN and compare the specifications and various parts used with the gearboxes to check. If the C&P are the same (which I doubt) it may well be possible to swap just the gearbox, keeping the HDI converter, ECU and all electronics. Control is all electronic, so the shift points depend on factors other than just the ratios and vehicle speed. If the C&P and/or effective gear ratios are different to what the HDi has, then the car will likely become very confused and register a slip fault almost immediately because the vehicle speed will not match what it expects for the engine output etc..

    The best option is to part out the Picasso and fix the HDi properly. It may well need only the pressure modulation electrovalve changed, but you would want someone to read the fault codes and work out what's going on. The first thing to do is ensure it's actually got enough fluid in it. Penrite have a suitable fluid and it's not dear, so maybe drop what's in there now and see what it looks like before going further. You should be able to drain about 3.5l from it and it shouldn't smell burnt. Burnt oil is usually very bad!

    Have a read of this thread:
    03 Citroen C5 2.0 HDI auto HELP

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