Well as some of you know i was having problems with the right side dropping , it became very bad after i flushed the system and would drop within 30 min .
so today i pulled the rear valve block and rebuilt it , to my surprise it was very easy to do and thought i would share some pictures of what i did .
i used the green o-rings that are CHF compatible .
it is very easy to remove and you will only lose about 3/4 liter of fluid .
jack the car and take the weight off the rear suspension , there are nice spots to put jack stands just behind the rear wheels .
here is the unit out of the car and ready to disassemble i removed the bracket and relief ball on the bench .


when removing the clips i placed a small screwdriver under each side while very carefully squeezing them with pliers .


once the clips are removed they are very easy to turn 45degrees , i then put a wrench under them to help with leverage and pulled them out

another handy pair of pliers to use

as you can see the o-rings are shot

block all clean

new o-rings installed

the other ones

all done and ready to go back in car


the solenoids are very easy to push back in and turn to where the need to be , everything is color coded but i did mark the blocks per color just in case i washed the paint off .
overall a very easy job and took about 2hrs to complete .
once i had it back in the car i lowered it down with the jack still holding the rear up to where it would sit normally and started the car for about 30 seconds and pushed the abc raise button on the dash and then lowered it , shut the car off and topped of the fluid about a half a liter .
started it again and cycled through the raise and lower about 10 times then topped off fluid , it now has been sitting for over 2 hrs and has not dropped at all , the o rings were very hard and were coming apart .
front valve will be next .

Dave

 

what did the rebuild kit cost? and did you get any ABC errors before? mine dropped on rear passenger side, granted im under warranty.

 

yes i had the ABC light come on the dash and a code on DAS saying right rear strut moves although locking valve is closed ( rear valve block).
cost me a $10.99 o-ring kit and $20.00 liter of CHF .
and the dealer would have got me over for something like 2k or more I'm sure ?

 

Welcome to the rebuilders club

I ve done about a dozen of them - all with splendid results.

It is an easy job.

And yes- the dealer would have charged you close to 2k.

Well done

 

ahh ok so there's no "official" rebuild kit then?

 

Great job. Where did you purchase the o-ring kit?

 

I believe this particular one is a available at harbor freight.

 

yes alx is right harbor freight has them . and the perfect sizes are in there , some of the square edge ones were also bad ( basically used as spacers ) so i just used a smaller buna o-ring to replace them .
i also stretched the springs about 3/16 longer .

Dave

 

I think this is great !!!! This is fantastic ! Glad to see people digging down and finding out ways to mitigate the price of parts !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!! !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!! !!!

 

Wow that's awesome. Thanks for sharing. Congrats!

Aaron

 

Bravo!

 

Please tell me someone in the UK does this??

 

Thanks alot for this. When mine (hopefully never) get shot i do the same for sure.

 

Switta,
You my friend, are the man. Any chance you feel like rebuilding a valve block for a fellow forum friend?? My 05 CL65 is sinking on the driver rear wheel approx a minute or two after turning the car off. Please get back to me, I would VERY greatly appreciate it!!
Thanks,
Dieter
614 256 5558

 

its not even mandatory to use chf either.. its simply synthetic hydro fluid with an UNusually high combustion temp..ive even used tractor fluid to flush the system when ive encountered dirty ones... in my opinion the best kind of fluid there is is... fluid that is CHANGED.. the fluid gets worked pretty hard during even mellow driving and it gets hot plain and simple..when heated over and over it gets dirty (worn out ) by itself.. unlike engine oil that gets contaminated from combustion..every problem ive EVER seen from ABC is lack of maintenence..im not real fond of the Pentosin ..there is better fluids available amsoil for example Whoever claims pentosin mandatory is probably should go work for pentosin lol

 

This is absolutely correct and matches perfectly to what i've learned about ABC from other users and companies here in germany. To root cause for almost ANY ABC problem is dirty fluid/oil.
Once its worn/dirty it acts like a liquid sandpaper inside the ABC system and start to kill all those hundreds of elastic gaskets/seal-rings first. Then you have the Problems.
The one ABC-specialized company for instace here in Germany recommends a 2year/20.000miles oil-change interval in the ABC system together with the 3micron filter.
They say they do this since they bought their first ABC car and it had ZERO ABC issues so far in 13 years (besides some electrical sensors).

Yes their are alternatives to pentosin for the ABC system. Early ABC equipped cars even came with red colored (more or less) ordinary hydraulic fluid.

Me and some others use "Meguin Megol Zentralhydrauliköl" green colored for the ABC System.
It has no named approval (yet) by MB Sheet 345.0, but it is clearly recommend by the manufacturer as alternative to the Pentsoin CHF11s and shares almost the same characteristics according to TDS.
Price is almost 1/3 of the Pentosin (7€/Liter for the Meguin and 17€/Liter for the Pentosin both in aftermarket)

http://www.meguin.de/meguin/produktd...id/e_6304.html

 

Hi,
Where do I get the CHF?
Thanks

 

http://www.fcpeuro.com/products/audi...FcqDQgod3UMAcQ

 

Hi,
So I want the CHF 11S Red Power Steering fluid or the CHF 11S Green Hydraulic System Fluid? I'm assuming the CHF 11S green but you linked me to the other page, JW.
TIA

 

For the ABC its the green one.

 

I got the oring kit and the chf. What is the process for the flush? Is the flush neccessary first before pulling the valve block for the rebuild? Do I need the buna square o ring as well.
TIA!

 

In the USA one can also get Pentosin at a large Advance Auto Parts. It is a stock item but call ahead. (I would avoid non-approved fluids esp. if you are under warranty.)

Make sure you use the dipsticks in the reservoirs on the driver's side towards the front to check the level. If you have to add Pentosin, make sure your funnel, etc. is sqeaky clean! Also, its best not to overfill it!

Search here or on other boards for the exact position of the reservoir unless you have STAR. It may also be in your OM.

 

O Man i would not be comfortable rebuilding someone else valve . i really appreciate the offer though .
it is a very easy job , just make sure you take the weight off the wheels and have the engine off for at least 15 to 30 min to relive pressure in the system .
have at it and I'm sure if you get into a problem there are many people here to help .
i also capped the main lines with rubber caps to keep the fluid from dripping out while you have the block out , you can get them at any automotive store there just vacuum line caps .
all you need to get the block out ( rear one ) is a 17mm wench and a 1/4" 10mm socket and small extension , the electrical plugs are color coded but i did scratch on the block and the solenoid the letter of each color just to be safe because cleaning may wash the color dot off .

Dave

 

if you have a valve block about to fail flushing the abc will bring out the problem for sure .
it washes all the derbies that may be sealing around the o-rings and causes it to leak by them .
i am glad i did it though my fluid was black and hydraulic fluid gets very hot and eventually brakes down just like break fluid . the debris end up like abrasive particles in your system , sure the filter gets a lot of it but fine particles are still running through the system and can cause early failures .
i ran into that several times with backhoes and loaders we owned throughout the years .
you don't need the square o-rings they really don't serve as a seal but more as a spacer , i don't understand why they did that ? they don't slide in the sleeve of the cylinder block so it couldn't be a resistance issue the piston in the solenoid slides , there is a square o-ring on it that would be nice to replace but you would have to be spot on with it to not bind the piston in the solenoid . just stack up o-rings or space them out with smaller ones . more o-rings better sealing IMO .

Dave

 

Great info!