SL-Class (R230) 2003 -- 2012: Discussion on the SL500, SL550, SL600

SL/R230: Value block sound?

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Old Apr 29, 2025 | 03:30 PM
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Kingkell's Avatar
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2008 CLS550, 2009 SL550
Value block sound?

Hello all, I have a 2009 sl550 with a hissing sound coming from the front abc value block. I see no fluid leak and the car is not lower. Only indication there is a problem is the sound. Anyone know what could be causing or suggestions on where/how to locate where coming from? Thank you.

Last edited by Kingkell; Apr 29, 2025 at 03:32 PM.
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Old May 2, 2025 | 03:13 AM
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Tom Manning's Avatar
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2005 SL 500 R230
Has it stopped?

There is no air in the system - only the gas in the gas cells. If one of them was ruptured then you might hear a hiss but it should stop pretty fast.

The only other possibility (If there are no leaks) is fluid leaking back into the tank but you would know that by the car lowering.

If there appears to be a gas leak you could spray the valve block with soapy water and look for bubbles.
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Old Jun 9, 2025 | 08:19 PM
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2005 E500, 2004 SL600
What is the cause of the fluid leaking back into the tank?

I rebuilt my valve blocks and now my car sinks and the tank has too much fluid.
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Old Jun 11, 2025 | 04:16 AM
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2005 SL 500 R230
Sinks both front and back?

The fluid is getting past the blocking valves - there is no other path back to the tank.

You will have to take out the valve blocks again and look for the leaks. Possibly some grit in the system.

Remove the fluid until the lines on the dipstick match up - engine on or off. The fluid level and the sinking are not related - chances are you just put too much in.
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