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2004 CL500
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Discussion Starter #1
I recently moved from Houston, TX about 6 weeks ago to Hoboken, NJ and since I have been staying in the city I've had my '04 CL500 sitting at my Dad's place. My Dad would start the car up once a week and once in a while drive it.
Well last week I went to pick the car up on Friday afternoon and noticed the front end was sitting on the front tires or just about that low - couldn't get my finger between the tire and the wheel well. I started the car and the car didn't raise up however I put the car in reverse and within 2 seconds the car raised itself back to the normal position - again this is just the front shocks.
I drove all last weekend and all was fine.
Monday night I drove it back over to Hoboken and parked it in a garage. Today, Thursday, I went to check on the car and the front end had dropped about a 1/4" since Monday night. I started the car and put it in reverse and the car pressurized the shocks to its normal level.
So do I have some sort of leak or is the car supposed to lower itself after a period of time?
I've had the car for over a year but can't remember if I've ever gone more than 2 days without driving the car.
The ABC pump was replaced about 17k miles ago.
Any help would be greatly appreciated.

Shane
 

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1970 w109 6.3, 2014 ML350 (petrol) AMG kitted, 2004 Vito 115 crewbus, 2003 CL600 V12 bi-turbo
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Hi Shane,
I have a 2003 CL600 TT and the front on mine can go down over night sometimes, some days it will stay up for three or more days when parked and occassionally it will drop down within a few hours especially in hot weather or round town running. The pump and front struts were replaced last year - so near new!
I think my valve block is probably not working that well. There have been several posts where very clever people have dismantled this block, cleaned it, replaced the 'o' rings and put back - and it works like new, saving thousands! I will do this one day.

I am not worried about the front going down on the car as long as it goes up again within a few seconds by either putting the car in gear an releasing the brake or by the raise button on the dash. And the red warning light does not come on while driving!
Would pay to check underneath to see if the hoses are OK and struts are not leaking. Also check the ABC fluid levels say twice a week to make sure it is not losing any. If not - don't panic too much - me or my MB tech (who is very good!) are not worried too much as there is no loss of ABC fluid. There are metal to metal seals in the ABC system and they do let fluid go from one part of the system to another internally.

I am no expert - no doubt others will be able to guide you better - just saying that I have the same problem and am not worried as there are no leaks in the system.
 

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'02 CL500
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376 Posts
I would say what you are describing is normal, including the car not rising until the car is in reverse with the brake off. I have an '02 CL500 that has been doing this for the last 8 years and has been checked by MB several times and they say all is OK. Dropping over night is another story. Just be sure there are no leaks and keep your eye on the fluid level in the reservoir.
 

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2004 CL500
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29 Posts
Discussion Starter #5
Thanks for the response Jud, Mcfischer, & Star.
Star - you mentinoned something about cleaning, replacing the o-rings in the valve block - is this a definite fix? I don't remember the car ever doing this - it's obviously losing pressure otherwise it wouldn't lower itself.
I guess if I wasn't so anal I'd be ok with this. My buddies tell me whoever gets this car (if I decide to sell it) is going to be one lucky person 'cause the car is in MINT condition - thanks to my willing hand to debit/credit card exchanges...
 

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'02 CL600
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98 Posts
The hydraulic oil is slipping past a seal with dirt keeping the seal open somewhere in the system.
I fixed this problem by having the system flushed and replacing the filters with the "new" finer updated Mercedes filters and new hydraulic oil.
You probably have some dirt sticking in the system holding a valve open.
Try this and you should have a far lesser dropping problem if any problem at all.
 

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2004 CLK 240 Coupe
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11,377 Posts
I've never had experience of an ABC system, and my interest in this issue is entirely academic...:)

The reported symptoms are intriguing. Rear suspension drops overnight, but recovers on start-up... This cannot be normal... the showroom models do not do this!

Studying the hydraulic diagram below suggests just one item is failing - Item #4, the rear axle pressure reservoir. After all, that is what it is there for - to maintain the pressure at the rear when the engine & pump are turned off. As soon as the engine starts, the level sensors are energised and the servo loop raises the rear of the car to the correct level.

Has anyone got a better idea?
 

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2004 CL500
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there's 2 different kinds of metal in the valve block. they expand/contract at slightly different rates causing some seepage while the car sits for a few days or more (especially in winter). the manufacturer (MB) claims this is NORMAL as long as the car raises to the correct height after starting, putting it in gear, AND letting foot off brake. it should pop right up when you do that :eek:
 

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1970 w109 6.3, 2014 ML350 (petrol) AMG kitted, 2004 Vito 115 crewbus, 2003 CL600 V12 bi-turbo
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403 Posts
The hydraulic oil is slipping past a seal with dirt keeping the seal open somewhere in the system.
I fixed this problem by having the system flushed and replacing the filters with the "new" finer updated Mercedes filters and new hydraulic oil.
You probably have some dirt sticking in the system holding a valve open.
Try this and you should have a far lesser dropping problem if any problem at all.
Yes - I have heard this mentioned before - I think I will get this done before looking at any block valves to see if it helps with the front dropping.
My pump at front struts (back stays up forever) were replced because the previous owner let it run dry and there was crap throughout the systerm from the imploding pump! Even though the fluid has been replaced once with the repair and again when I fixed some leaky hoses - there could still be crap in the system. Will get the newer filter fitted.
 

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'02 CL500
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376 Posts
Adding to my above post and for what its worth, MB replaced the front valve but this did nothing to help the left front side drop which occurs after a several days of sitting.
 

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2004 CL500
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29 Posts
Discussion Starter #11
Dutch - thanks for the reply. What can I expect to pay to have the system flushed and new filters replaced?
Is there a name for the new Mercedes fluid?
 
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