4 Hp 18 Box Stripdown, CitroJim this is all your bl**dy fault

Hi all

Right, my autobox is starting to die, it seems to almost stall the engine as i came to a stop and my 3rd to 4th gearchange is getting lumpy, i have been reading up on a Saab site and this, apparenty, is down to just one £2 spring in the bottom of the valve block.
Now the good box in my garage could go in with a straight swap but since i think my problem is valveblock related, and i have been inspired by Jim, i have decided to take the plunge and take the PERFECTLY GOOD spare box apart and put its valveblock into my ill box and thus ovoid removal of the engine etc etc.

So here it is, one 4 hp18 box in fine health (wtf am i doing )



Undo the 4, 10mm bolts that secure the top cover and hey presto you are staring at the valve block



once i had found which of the bolts held the entire block in place, out it came. Note the selector has to be in 1 to allow the valve block to lift out


Which left this, very un intimidating actually, note the brake band adjuster on the front of the gearbox casing and the kickdown mechanism on the back left and selector mech at the back right corner,

Now i need to do some reading up, if anyone has any info on the hp18 can you please let me know and post it here with any links.

Thanks
D

Well done for just diving straight in Dean.

TBH with the apparent mysteries of the dreaded autobox, pictures and information about stripping the thing are something which is long overdue, and may be of immense benefit to fellow members on here

Ciarán

Tbh Ciaran so far its not as complex as i thought and everything seems to be made to come apart easerly and as units.
The Saab forums are way ahead of us lot, they know the autobox probs all too well and have identified the faults, sourced parts and many members seem to think nothing of striping an auto, trouble is they are in America

Hopefully we should be able to get some good info together when this is done and lessons have been learnt and i can put together a precise waffle free post in the self help section.

D

I noticed that with autos being so common in America, there is a far greater knowledge pool, parts availability etc. Also as you say, they think nothing of just pulling them to bits.

There are plenty of autobox specialists who will rebuild them for reasonable prices too.

Seems they're not all that daunting afterall.

Ciarán

Dean

Very good pictures, I understand that its easy to disassembly from top, without removing from car. How many miles on the clock to have such a problem?
Is this regularly maintained?

Caique

Well this is where it gets interesting my box, the failed one, has done 90200miles with a full history and serviced by me at 5k intervals (max) the fluid has and is always clear red and its starting to die.
The good box in the photos has done 93000 miles and is perfect but has no history and the oil in the box is black as hell (see pictures), and due to bad coolant the heat exchanger is all clogged and rusty too so that seems to blow the 'keep the fluid clean and the box will be fine' rule out of the water doesnt it

D

The box is stuffed..... Someone has poisoned it with DIII right ??? It turn black and sludges up all the valve block etc.... and contaminates the clutches. DIII will destroy BX/405/XM/Xantia slugomatics incredibly quickly... It's death to the gearboxes.

seeya,
Shane L.

Well this is what i have heard, but the americans use DIII in these boxes now, saying it has replaced DII but im not going to be using DIII.

Shane the black horrible oily box in the picture is the good one..........
The one on the car that has been loved with crystal clear oil is the one thats dying (pictures to come)

D

Hi Dean

Have a copy of: 4HP 18 Automatic Trasmission, Checks, Repairs and Adjustments.
It came with the Pug stuff, is dated 1990 so is not Citroen specific.
Topics covered:
General p 2-9
Fault finding proceedure p10-35
Adjustments p36-43
Repairs in situ p44-57
Repairs with gearbox removed p58-61.

The equivalent 4HP 20 book is a lot slimmer, not yet looked through the AL4 ones.

No scanner on line and no capacity on the hard disk for any more data at the moment.
Can make a photo copy over the next couple of days if this will help.


John

This post has been edited by xmexclusive on March 02, 2009 11:50 am

Hi Dean.

Probably a dim question, but why not buy the spring new and leave your good spare box intact ?

Mike.

Come on Mike, where's the fun in that .

John, if i could have a copy of that manual it would be perfect, thanks, i need to see how it works before i go any further really.


D

This post has been edited by dean on March 02, 2009 07:45 pm

I've just seen this thread Dean. Sorry

Good stuff though

These autoboxes really are great fun once you get stuck in.

Well if the valve block swap cures my box problems then i will take the duff block apart and see if i can put it right, purely for the hell of it, then after ive gained a little confidence i may get a re build kit for the hp18 box thats on the turbo engine that i have and rebiuld that so its all good for when i swap it all into the prestige later this year, early next..............fingers crossed

D

Hi Dean,

I think the work that you and Jim are doing is tremendous. One piece of information that's missing is just what the selector lever does. Does it operate directly on the valve block?
Another thing, we must not allow the info that you two are gathering to just disappear into the limbo of past posts. There must be some way of making it instantly available in the future.

Derek

Derek,

As far as i can see at the moment the selector operates one slide valve on the bottom of the hydraulic block with a seperate shaft which dives into the bowls of the box, im sure it operates not only the locking pawl but also something else because it moves 7 stages with the lever, if it were just to operate the pawl im sure it would move only once when park is selected but i will find out.
I have started another post already in the self help section which i plan to keep waffle free, and when the job is done i will put all photo's there with a clear step by step guid, if i can figure it out.

D