4HP20 Xantia/C5 interchangeable?

[jensmn]

Hello - I am happy to join this Forum, seeing the amazing level of information here. I spent most of last night reading and I am really impressed!

Now to my problem: I have a very fine Xantia V6 etstate 1998 - the car is in super condition and with all options including black leather interior. I spent too much money on it through the last years and my intentions are that the car should be kept immortal. It has now 257.000 km. One week ago what happens also happened to me: The death of the gearbox. With all the problems and noise very well decribed in this and other forums...

Finding another gearbox is my best solution - I use this car everyday, and I need it. But finding another is not that easy, even if I have many contacts. And if I don't want to face the same story soon again, I need to get one with low mileage.

I found one! 4HP20, well tested, fair price, only 125.000 km. But it comes from an early C5 V6, not a Xanthia V6. Looks the same, only I can see that some attached parts differ from the Xantia (eg. cooler) but my question is: Can I use this gearbox?

If you know, please reply immediately and I will startup any old Citroën to get my fingers on the 4HP20. It's not exactly in my neighbourhood.

All the best to you all!



Jens

[lexi]

Not sure of the accurate answer to this. My instinct says there will be problems.
The C5 was a totally redesigned car. Even the V6 Engine was rebuilt with scores if not hundreds of changes.

ECU's will be first problem and then the fact that there may be slightly different versions of 4HP20 for engine application. ie gearing to exact engine power. The later V6 has 210 bhp as opposed to earlier 194.

Your auto box lasted a fair few kilometres.

[jensmn]

An information that might help:

Chassisnumber of my Xantia: VF7**************[VIN obfuscated, can be read by forum staff]

Chasssisnumber of the C5: VF7**************[VIN obfuscated, can be read by forum staff]

[myglaren]

Adam can't have seen your question but look here then ask him directly (PM him).

[jgra1]

well spotted Steve..

I do have an 80K km HP that I might sell..406, same engine, I could even be coerced into driving to Denmark ..

To be honest, I need 2/3 weeks to decide, as the car it is for may be sold (in which case the box is free to sell )

[addo]

The only way I know to confirm interchangeability, is to first confirm the identity of each gearbox as "true" to its originating vehicle (rather than swapped earlier in life).

Then print off the parts sheets for each one from Service.Citroen and sit there with a couple of ballpoint pens, marking off similar items and highlighting different ones.

For any transmission swap that includes a locking torque converter, I think a reputable rebuilt unit is a good idea.

[CitroJim]

I can't comment on the interchangability between the C5 and Xantia sadly. Whilst a 4HP20 may look the same internal gear ratios may be different and that alone will cause the ECU problems.

If you can't find a replacement easily, consider rebuilding yours. It's not as difficult as it looks and a lot of information is here on how to do the job.

Spares are freely available and I've now done three of them now.

What happened to yours? How did it fail?

[jensmn]

The last couple of houndred kilometers there was a sound - a bit like a dry/worn bearing. Next was lack of drive and emergency mode. My guess (after having read a lot here and in other forums) is that the converter has broken down, probably as a result of a blocked oil filter. I presume that I am among the poor people who had the Dextron disease, of course without knowing it. Time will tell - surely the whole story has made me curious, and I will definitely find out once the broken gearbox is out on the table (sooner or later).

Today I bought another fine Xantia V6 for parts. It has a bit more than 200.000 kms, but the gearbox is known to have run on LT71141 oil and it is absolutely silent and very well working. It goes right in my car without discussion - and I will have the damaged box to play with (I am highly inspired to do so). And many other good spares for my car.

Driving this "new" donor-car today i realized that the transmission was absolutely silent. I am wondering if my own car had a little noise all the time I drove it (about 65.000 km). When accelerating while the converter was not locked there was some mechanical sound - not loud or dramatic. Difficult to describe it, but there was a sound. But it is missing in the "new" car. So I feel very optimistic about using this gearbox.

I really want to thank all of you for your advise and help - I am amazed to realize that it involved people from all over the world! Let me know if anyone are in need of spares - the donor is a 1999 Xantia V6 Exclusive automatic, only missing the gearbox! (Well, there's a few things more to be kept for my daily car).

All the best!



Jens

[CitroJim]

It sounds like it failed in the usual way then Jens My belief is that the lock-up clutch in the torque converter fails and breaks up. This puts particles of friction material in the oil which blocks the filter and a vicious circle then develops.

The noise you heard is likely to have been a seizing torque converter neck bearing - it and the output shaft bearings are the first to suffer when lubrication becomes marginal.

A V6 estate would be very desirable. We never had those in the UK

The old 'box may not have suffered too much harm and will be rebuildable.

Please you have found a replacement. It is very wise to get one from a known running car. Buying one that is said to be good is very risky in my experience...

[jensmn]

Hi Jim!

I have been really glad (and very impressed!) to read almost all the posts in this forum concerning the 4HP20 - not the least the many ones posted by you. I also studied your 4HP20-site carefully. I it so nice when mysteries are brought down to earth and you realize that things can be done. I still haven't touched a single bolt, but I have a feeling of knowing something about these gearboxes now - something I would never have dreamed about before. And I am sure once the gearbox swap is done I will take the damaged one and put all the parts of it on the table to see what went wrong - and rebuild it if I can. It's a nice challenge!

We have quite many Xantia V6 estates in Denmark. I know it is a rare car in many coutries; in France the model was never sold - another guy once told me that there was only one in Holland (I wonder how he could know). The donor-car is an estate as well and it is a bit heartless to scrap it - everything works very well in it and with a few new parts (including spheres!) I could drive it for another year before MOT. But... some must die to keep the others alive! And have great confidence in the gearbox which, as I wrote, is absolutely silent and runs smooth and well. I will drive the car and test it during the next couple of days before putting her on the scaffold.

But I look forward to get back in my "own" car. Not only an "Exclusive" model, but with more extras including black leather seats, engine/cabin heater and more. Of course it's a car from way before common sense took over, completely outdated by the economic eco-cars of the present. Luckily I don't have to use it long distance every day. But everytime I start the engine and feel the balance of all the components of the car when I drive, it makes me extremely happy in my head! And.... being happy in our heads is the best reason to stay around!

Thanks again!!!

Jens

PS.... you will probably hear from me again when I get the 4HP20 under the knife!

[lexi]

That is great news.

You could replace the filter and fluid in your replacement box while it is out.
V6 is a fun car with character. You realise this when you drive a few souless vehicles
and then can't wait to get back in to what is quite a unique package.

[jensmn]

Yep, it's a fantastic car. To change the filter you must split the gearbox in halfs - I don't really feel up to that, but of course the oil can be changed...



Jens

[lexi]

To change the filter you must split the gearbox in halfs

Yes. I think Jim said not too difficult. I may be mistaken but I think he will encourage you do do it. ?

[CitroJim]

To change the filter you must split the gearbox in halfs

Yes. I think Jim said not too difficult. I may be mistaken but I think he will encourage you do do it. ?

Yes, sadly you must Jens and this is effectively a full stripdown requiring new gaskets and oil seals on reassembly. It is in reality a big job but it would allow you peace of mind to see all is well. Beware that what I see as an easy job is not necessarily so to others

There is no easy way to get to the oil filter and this is really a piece of bad design on the part of ZF.

However, having said that, I would recommend you have the torque converter rebuilt as this is far and away the component most likely to fail. A rebuild is not that expensive in tyhe overall scheme of things.

[jensmn]

Maybe I'm mad. But my gut feeling about the doner-car gearbox is that it is very healthy and good for another 100.000 km. I need my everyday car, so we will throw the box in it within the next days. (Being done by a Citroën garage as I have no time for it). But the broken gearbox I am sure I'll try to rebuild it - and keep it as spare. It might be difficult for me - but if you are right, Jim, it's not too damaged and with a bit of help and good advise I think I can do the job. I've done work on traction gearboxes before - not too dificult, but of course a kind of job where you have to work with precision and care.

Well, nothing is difficult if you know how to do...

I drove the donor car today - I think it's almost terrifying that such a car has do die. Not that much wrong with it, but the price of it was just around 800 euro. Well, that's why they die...



Jens