SL/R230: NOISE FROM TRUNK AT STARTUP
Thread Starter
Member
Joined: Jan 2018
Posts: 152
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From: Nashville Tn
2011 mercedes sl550, 1995 corvette
NOISE FROM TRUNK AT STARTUP
Ocassionaly at startup, I hear. something running. I’m assuming it is the pse pump. Doesn’t do it every time and it runs for just a few seconds then quits. Everything is working as it should. Does that sound like a PSE pump? Is it “normal” for the pump to run at startup?
Senior Member
Joined: Jan 2015
Posts: 389
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From: Seattle, WA
SL500
It's most likely the SBC pump that you are hearing. If you want to confirm, open the hood and goto the right front side of the car. Then have someone place the key in the ignition and turn it to the #2 position. Is the sound you hear the one you are referencing? That's completely normal.
If that isn't the sound you're referencing, then it's most likely the rear ABC accumulators you're hearing, although it's most common to hear those on shutdown as opposed to startup.
Bottom line is both the SBC & ABC systems are high pressure and need to go through both priming and relief cycles.
If that isn't the sound you're referencing, then it's most likely the rear ABC accumulators you're hearing, although it's most common to hear those on shutdown as opposed to startup.
Bottom line is both the SBC & ABC systems are high pressure and need to go through both priming and relief cycles.
Senior Member
Joined: Feb 2018
Posts: 258
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From: Gluckstadt, MS
2003 R230
PSE, CD changer, Comand Unit fan, SBC and ABC can all can be heard at times when you put the key in the slot pre start and post stop. From experience I can tell you that if you hear a short light "thump" from the trunk more than three times in a row you most likely have an air leak and the PSE pump will soon be getting to the point of timing out. When that happens the soft close trunk and lumbar support are the first places you will see affected.
Thread Starter
Member
Joined: Jan 2018
Posts: 152
Likes: 36
From: Nashville Tn
2011 mercedes sl550, 1995 corvette
Thanks for the reply. I’ve only owned the sl550 for 9 months so am still getting used to the hum of moters/pumps etc. that occur on startup and shutdown. Not sure what’s normal or what’s a problem. None if the noises last for more than a second or two, and everything seems to be working normally. Great car, really fun to drive. Thanks again
MBworld Guru
Joined: Dec 2009
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NO LONGER ACTIVE
The PSE pump in the left side of the trunk makes a very soft, gentle-sounding electric motor noise. The SBC pump in the front right corner under the hood makes a very loud "compressor" type noise. Both of these are normal to hear when unlocking, opening the door, inserting the key, etc. If either runs more than 30 seconds, there may be an issue. Especially with the PSE pump as the various pneumatic equipment, like the trunk latch, can leak and cause it to keep running.
Thread Starter
Member
Joined: Jan 2018
Posts: 152
Likes: 36
From: Nashville Tn
2011 mercedes sl550, 1995 corvette
THANKS
THANKS RODENY, always appreciate your input. Pretty sure it’s the PSE pump I hear on occasion. It’s definatrly coming from left rear. Only does it occasionally, and only for about 8 to 10 secs. I just didn’t know what noises were norm. After reading about all the horror stories about ABC, PSE, etc, etc, I was about to sell my SL, even had a buyer, but just couldn’t do it. Love the car too much. Just gotta find a good Indy. Just in case
