[W126 Coupe] [W126 coupe] Hissing sound behind the cluster

[Mister McGoo]

The "economy" gauge is nothing more than a basic vacuum gauge.  At idle the vacuum is maximum, as you accelerate the vacuum goes to towards zero.  In your case, the rubber vacuum line connection has come off the back of the gauge (common) or has broken (rare) and hense the hissing which goes away on acceleration.  Mercedes did that for a number of years.  It's a bit of a misnomer as sitting at an idle and not moving is NOT exactly an economical thing to do.  Cars with diesel engines of course never had this.  
-Bellamy
 


Date: Thu, 28 Apr 2011 04:41:25 +0400
From: usef4188 at gmail.com
To: mbcoupes at mbcoupes.com
Subject: [W126 Coupe] [W126 coupe] Hissing sound behind the cluster

Hey Guys


There is this hissing sound that seems to be coming from behind inst. cluster and as i accelerate it disappears. What could it be? and is it normal?


Thanks-- 
---------------------------
Yousef Nazzal
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