Air suspension going down on Rear.....help please. - Club Touareg Forums
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post #1 of 52 Old 08-18-2018 Thread Starter
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Unhappy Air suspension going down on Rear.....help please.

I have tried posting on several Porsche web pages to no avail. Appreciate it if anyone can help.

I have a 2006 Cayenne Turbo S with air suspension.

The rear of the car is going down over night by approx 85mm, the fronts are at normal height.
If I unlock the car, (without getting in) the accumulator discharges air and pumps it back to normal ride height. There are no fault lights on on the dash.\
If I put the car in Jacking mode the results are the same.

I have sprayed the soapy water on the rear air springs and there is nothing obvious, I think i need to take them off and dip them into a bowl of water or something.

Are the two air shocks connected together somewhere if so where, I think there is a leak and the other shock is leaking into it. Is there a T piece somewhere or do the air connections both go back to the block on the right hand side....

I am happy to test or remove anything but need some guidance.

Please help
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post #2 of 52 Old 08-18-2018
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When you start the car, does the suspension on rear go up or does it still stay low?
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The leak is after the distribution block located at the compressor. So the places to check are the air line back to each shock (which very rarely leaks), the RPV (residual pressure valve) which is at the top of each shock, and lastly the shock itself.

After the air line, the least likely part is the air shock. They do leak some, but it is about a 20% chance it is the spring.

The RPV are a known problem. They stick shut and cause the "rear end won't go down problem. They also often leak, where they are screwed into the top of the air shock. 80% chance the leak is here.

The leak can be really slow. Sometimes it is hard to find with soap bubbles. Get the bubble soap solution from the kid section of a store. Coat the area with the sticky soap. Start the vehicle. Let the rear rise. It can take 15 minutes to sometimes see the leak.


aerosus.com/vw/touareg/vw-touareg-residual-pressure-holding-valve-rear


clubtouareg.com/forums/f44/how-to-replace-a-residual-pressure-valve
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post #4 of 52 Old 08-18-2018
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"If I put the car in Jacking mode the results are the same."

The results are the same as what??? Does the rear still go down overnight? Please be more specific. Thanks!

X2 on checking for leaks with soapy water. spray the solenoid valve block, too. remove the plastic cover where the compressor is. The valve block is the device where all the hoses enter into.

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post #5 of 52 Old 08-19-2018 Thread Starter
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OK thanks for the replies, here are some of my replies :-

1) When you start the car, does the suspension on rear go up or does it still stay low?
When i unlock the car the suspension raises to normal on the rear, the front does not move as it is at the correct ride height. When i start the car the compressor runs, i assume to recharge the accumulator then it goes off approx 60secs of run time.

2) "If I put the car in Jacking mode the results are the same."

The results are the same as what??? Does the rear still go down overnight? Please be more specific. Thanks!

.......So the vehicle is losing height at the back overnight by approx 85mm, the suspension is in normal setting and normal ride height. If i put the car in jack mode and lock the car and walk away and leave it 24hrs, the car lowers on the rear by the same amount ie 85mm. when i unlock the car the accumulator discharges and raises is back to normal level, if i start the car the compressor kicks in and recharges the accumulator. putting the car in this mode makes no difference to the end result.


Just one other point, 600 miles ago the car went into Porsche to have the PRV replaced as the rear was stuck high. They replaced both PRV's on both rear shocks. As this was such a simple job I did not think that they could get this wrong, ON BOTH SHOCKS ??

The schematic in the manual shows that the shocks are joined together via a Tee Piece then they go back to the distribution block, is this true ? by what you say they both have their individual air lines going back to the distribution block. If this is true why are both shocks sagging, surely one would stay up and the other down if there was a leak in one of them. Does anyone have a schematic / drawing.

Thanks again, comments please.
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Sorry I meant RPV's .....

Could I take the shock off and check the RPV's and put some compressed air in it somehow, jubilee clip some pipe over the RPV and use a regulated compressor to but a few PSI in it and then check for bubbles ?....check it on the bench.
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A quick photo, I have also some video but unable to upload for some reason
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OK I have found the leak and it is on the same point both sides. The LHS is leaking but not as bad as the RHS.

Basically, the valve is NOT leaking, it is above the valve where the top of the shock mount saddle (item no 5) meets the air spring (item no 7) . I can see that there is a large diameter O ring inside (item no 5) , I am guessing that if I replace that the issue is fixed ? or could be.

Anyone know if I can buy this separate or is it a full rebuild

Thanks
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post #9 of 52 Old 08-19-2018
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If it is the pipe itself at the end, then you can just trim the 5mm or so and reinsert it into the shock. Common fault
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Quote:
Originally Posted by Gabicolon View Post
When you start the car, does the suspension on rear go up or does it still stay low?
Quote:
Originally Posted by gazaflash View Post
If it is the pipe itself at the end, then you can just trim the 5mm or so and reinsert it into the shock. Common fault
No it is not the pipe, it is as per my explanation at the top...photos attached
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