ADS2 - pump priming/system bleeding (2024)

Hello everyone,

Please can you help a noob?!

I've just refitted the tandem pump on my 2000 R129 SL500. I didn't lose a lot of hydraulic (ZH-M) fluid in the process - indeed the level in the the reservoir on the front wing barely dropped - it has remained just on the max mark.

Does anyone know if I need to prime the tandem pump and if so, how? Do I need to bleed the ADS system? I note from the ADS2 shop manual (available on Brian Clifton's R129 site) that the system should be self bleeding, but others the suggest that the system might need the Rodeo proceedure carried out. I thought the Rodeo bleeding procees was only for ABC?

Any help much appreciated.
Thanks,
Justin.

@Richard Moakes is your man for this...

LostKiwi said:

@Richard Moakes is your man for this...

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Never dealt with ADS 2, I know it's much more electronic than ADS 1, and I believe a bleed/rodeo procedure needs to be performed using the HHT or the Star HHT emulator.

Thanks chaps. The weather stopped play today but I'll take another look after I've changed the harmonic balancer later in the week.

If I do need to get it on a Star/HHT system, can anybody recommend a mobile specialist who would travel to Oxford?

Justin.

Just an update. Thanks to Alastair, we managed to pull a "Y36/6y1 Error" from the car. We also managed to raise and lower the rear using HHTWin, but the front remains unresponsive. This morning the car was sitting very low on the O/S/R and the ADS remains out of order.

I haven’t done a lot of Googling yet, but it seems pretty clear that the fault code we saw relates to the solenoid valve y1 which is the “raising front axle valve”. This is one of the four solenoids fitted on top of the valve block.

A few people have reported issues with the wiring between the connector on the strut top and the solenoids. Indeed, one chap found that the wires were shorting against the metal solenoid body giving him an intermittent fault.

I think my next step may be to try and test the wiring between the Y36/6x1 connector block on the front offside wing and the solenoids on the valve body. I guess the next step would be to remove the valve body and solenoids and try and inspect/rebuild/send off for repair...anybody know anyone that can rebuild ADS 2 valve bodies?

Cheers,

Justin.

Justin85 said:

That's a great help, thanks guys.
I suppose if it's the solenoid actuator itself there's not much to be done. I'll get investigating.
The fun never stops!

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It may be interchangeable with an ABC one if you're lucky (and I know where there is a spare one of them).

Not much time tonight, but I did manage to get the multimeter out. I'm no electrican, so forgive me if this is a nonsense, but I thought I'd try and test the resistance from the connector to the valve block solenoids. The connector has 5 terminals numbered 1-5. 1 is the largest terminal - the earth for all 4 solenoids I assume. The other 4 terminals are the 12v feeds to each solenoid. I measured 9 ohms resitance at two of the terminals, 6 ohms at the third terminal, and 0 ohms on the final terminal, 2. I haven't found a wiring diagram yet that shows enought detail, but I assume terminal 2 is the live feed for the solenoid y1 which is the front raise one in question.

As said, I don't really know what I'm doing, but would a reading of 0 ohms suggest an open circuit? So the solenoid is shorting out (or the cable feeding it is)?

Cheers,
Justin.

0 ohms would suggest a short circuit. Definitely suspicious!

I've seen a few posts suggesting the wires can chafe and short to the body. I think you may be heading under it next time for a really close look. Do not put 12v on it as it could damage things further.

Bit more progress..

I've got the valve off the car and cleaned it up. No obvious wiring defects sadly, and the local small motor/solenoid place has a had a good look at the unit this morning as said they are not repairable as they don't come apart.

I've also spoken with the the solenoid manufacturer, Rapa (now owned by Juntec) who are unable to offer a rebuild service or a replacement solenoid as they are obsolete. They also don't resemble any ABC solenoids, which are relatively available.

So, I have ordered a replacement valve body from MB, which I should be able to collect on Tuesday, and hopefully fit Tuesday/Wednesday...

And I thought Porsche parts were expensive!

Justin.

New valve in and fitted....and all seems to be working just fine (fingers crossed!). As soon as I started the car after changing the valve the system started filling and after a few minutes at moderate engine speed, whist making sure that the hydraulic fluid reservoir was topped up, the system was full, self bled, and the car started to rise. The ADS light extinguished and the car raises and lowers as one would expect.

Interestingly, pre '95 cars with ADS have an additional plastic cover inside the wheel well which protects the valve from the elements. This was apparantly discontinued after this date leaving the valve block open to the elements. Not fantastic, for a component costing four figures! Yet to determine if the pre '95 cover will fit a newer R129.

Justin.