4hp18q Automatic Transmission

[dean]

I am Planning on composing a 'how to' on rebuilding the titled gearbox along with any information i find along the way, it may take some timebut for starters......

[CitroJim]

Excellent stuff Dean That'll sit beautifully with my 4HP20 efforts...

Looking at the expolded diagram, it's pretty much conceptually similar to the 4HP20 in that it uses all clutch-packs and no band brakes. That has to be good.

Another good thing is that it has a removable sump

I shall be watching with great interest.

Keep the camera with you at all times!

[Dieselman]

This might help for the HP20.

HP20 innards

[mich@el]

Hello Dean and other Xm maintainers

I have posted a prescription on auto gearbox oil change in “Introductions”.
But it might be more relevant here in “Self help” files, so here is a duplicate.

_ _ _ _


The 4HP18 autogearbox has to have clear red DEXTRON III / or the original by ZF prescribed Dextron II.
But take care when changing oil, somewhat 3,2 litres (my measurement) out of 8 litres when a change is made. The oil level has to end up in middle of the “warm indication” for normal driving. This leaves a proper expansion area for city driving on a hot summer day. But anyway selct N (neutral) with idling in a traffic jam.

Receipt for a service on the 4HP18 autobox:

Warm engine and gearbox /after at least 10 miles of driving.
Let the oil out (the side of the box near to the bottom hexagon 8 mm)
Remove filter (bottom lid with three 8 mm bolts)
>> Beware of warm oil / use old garden glove
Remove filter
>> Beware of more warm oil
Clean filter and the magnet in lid (6 grammes of deposit cab be held there)
Reuse filter if net is ok
Refill - through the dipstick - with the same amount as emptied out.
Check oil level / warm marking is accurate.

NOTE: If DEXTRON III is new to the gearbox you have to be keen on changing with short intervals because it has more cleaning power han Dextron II, and loosened residue can be dangerous.
Never the less if the colour of the gearbox oil is far from clear red, oil changes has to be made with short intervals.
If color is red and the smell is like new oil then change regularly at 16.000 miles.


If the oil is burnt the gearbox is in danger, complete change of oil can be made by flushing.
Empty out – through the cooler connection _ and fill through the return hose to the gearbox.
This takes 10 litres or more and the adjustment of the level will be time consuming.

The mechanical adjustment can only be made on tolerances on kick down cable and brake bands, but if the box is working properly then leave this out.


Best regards


Mich@el

[DoubleChevron]

Using Dexron III in these gearbox appears to be a death notice to them. Every gearbox I've heard of that has had dexron III put in it in Australia has required a very expensive full rebuild in the very near future here. BX/XM/Xantia gearboxs are known for failing at great cost at very low milage (eg: less than 80,000kms from new). The only reason anyone can find is they get poisoned with Dexron III by people that don't understand Dexron II and Dexron III are completelly different fluids!

The few people that investiaged this a while back found dexron III will competelly block up the valve block with "black sludge" in a very short time. It must effect the clutch packs and cause them to break down and distribute the material through the gearbox clogging everything up and turning the fluid deathly black.

DO NOT USE DEXRON III IN ANY GEARBOX UNLESS THE MANUFACTURER SPECIFICALY STATES TO USE IT.

The ONLY oil that should be used in these gearbox is Dexron IID as specified by the manufacturer. If Dexron III was directly compatible, why is Dexron IID still sold ??

seeya,
Shane L.
PS: I'm looking forward to this thread progressing. I have two XM's here with dodgy gearboxes, and a friend has one with a dodgy gearbox too. The gearbox and strut mounts are the greatest downfall of these cars.

[robertmnorton]

Hi all,please read reply to my email of 31/03/2008 from Martin Vogel of ZF.
robertm.

Robert,



the fluid service intervals for your ZF 4HP18Q are 40.000 km. Approved for use are ATFs according ZF lubricant class 11A or 11B.



If you can not get one of these fluids you can use mineral based ATFs according to GM specification Dexron-II and / or Dexron-III. Synthetic based fluids (especially ester base fluis) can possibly cause problems with the used elastomere materials in the transmissions (leackage !). Therefor we recommend use of mineral based fluids. The difference between Dexron-II and Dexron-III ATF formulations are mainly in use of different base oil combinations concerning viscosity (not base oil type !) and different additve packages concerning further requirements on clutch performance.

We can not recommend use of other fluid types because they can be critical concering necessary performance in the clutches (shift quality).




Mit freundlichen Grüßen/Kind regards
Martin Vogel
Schmierstoffe und Polymere (TW-L) / Lubricants and Polymers (TW-L)

ZF Friedrichshafen AG
88038 Friedrichshafen, Deutschland/Germany
Telefon/Phone +49 7541 77-7181, Telefax/Fax +49 7541 77-907181
martin.vogel@zf.com

Vorsitzender des Aufsichtsrats: Rainer Thieme
Vorstand: Hans-Georg Härter (Vorsitzender), Willi Berchtold, Uwe Berner, Michael Paul, Wofgang Vogel
Sitz: Friedrichshafen - Handelsregistereintrag: Amtsgericht Ulm HRB 630206





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She said what? About who? Shameful celebrity quotes on Search Star!

[DoubleChevron]

I know nothing about oils, or the differences between Dexron II and Dexron III.... The differences maybe tiny. All I know is gearboxes appear to die out here if you put Dexron III in them. As proven over and over and over and over again in BX's, Xantias and XM's

seeya,
Shane L.

[demag]

Shane I do remember reading a very comprehensive article by Alan some while back which I think I saw on the AussieFrogs forum.

[Sharo]

Hello everybody,
just to clarify these issues with DexronII/III:

In Australia/NZ i think the most problematic automatic gearboxes are in Citroen DS ( BW35 transmission ) - it uses "Type F" oil which is mineral (approved replacement is "Type FA", and it is totaly forbidden to use Dexron II/III etc - the failures are as described by DoubleChevron. The frictious materials deteriorate in D-type oil.
In 4hp20 or AL4 also is forbidden to use DII/III - only approved oil is LT71141 - side effects when using Dexron are gearbox overheating (including melting of plastics inside) - if you are interested i can put some pictures of 4hp20 driven 100km with Dexron III.
For 4hp14/18 there is absolutely no problem using DIII - both mine XMs (one has 300 000kms, the other one 40 000kms) are filled up with DIII. Last year i had to repair first one because of broken bearing - there was no defect on friction materials (only this bearing and few rubber o-rings on the governor were replaced).

p.s. if you are interested i can post 4hp18 and 4hp20 repair manuals (edit: 9mb for 4hp18 and 20mb for 4hp20)

This post has been edited by Sharo on August 15, 2011 01:47 pm