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  #1  
Old 10-07-2007, 08:29 PM
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Question Sound after shutting engine off 1984 300D

After shutting the engine off, I often hear something (a fluid?) circulating or whooshing under the hood. It's noticeable for about 60 seconds after shutting off the engine before it dissipates. What am I hearing?

84 300D turbo

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  #2  
Old 10-07-2007, 08:57 PM
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sealed coolant system depressurizing?
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  #3  
Old 10-07-2007, 09:19 PM
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im going with the coolant...
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  #4  
Old 10-07-2007, 09:21 PM
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Vacuum component?
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  #5  
Old 10-07-2007, 09:38 PM
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Quote:
Originally Posted by Sbean View Post
Vacuum component?
possibly. I had a leaking vacuum check valve and the vacuum escaping could be heard from the drivers seat, windows up.
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  #6  
Old 10-07-2007, 11:47 PM
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The vacuum transducers in my car make some noise until the vacuum bleeds off of the component side. Not sure how many an 84 has, but I think there's one for the EGR.

Have you been using the A/C? My dad's Volvo S70 makes a quiet hissing noise as the A/C system equalizes after the car is shut off.
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1990 300D 2.5 Turbo -155k
2000 E430 - 103k
2014 Jeep Grand Cherokee Ecodiesel 4x4 - 11k
2014 VW Passat TDI SE - 7k Bro's Diesel
2006 E320 CDI - 128k Pop's Benz


Pre-glow - A moment of silence in honor of Rudolph Diesel
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  #7  
Old 10-08-2007, 12:19 AM
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Quote:
Originally Posted by 2.5Turbo View Post
The vacuum transducers in my car make some noise until the vacuum bleeds off of the component side. Not sure how many an 84 has, but I think there's one for the EGR.

Have you been using the A/C? My dad's Volvo S70 makes a quiet hissing noise as the A/C system equalizes after the car is shut off.
Haven't been using A/C; too cold in the Pacific NW this time of year. The windshield swipers have been getting a good workout though
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Old 10-09-2007, 12:48 AM
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Ah, so true. My home (and my Benz) is in the NW, but I'm at school now in New York.

Without A/C, I'd look into vacuum stuff. Has this noise just started, or has it always been this way?
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1990 300D 2.5 Turbo -155k
2000 E430 - 103k
2014 Jeep Grand Cherokee Ecodiesel 4x4 - 11k
2014 VW Passat TDI SE - 7k Bro's Diesel
2006 E320 CDI - 128k Pop's Benz


Pre-glow - A moment of silence in honor of Rudolph Diesel
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  #9  
Old 10-13-2007, 06:56 PM
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I popped the hood after running the car today and found the source of the noise (see photo). It is located in the front of the engine bay on the passenger side, and makes a buzzing sound---I can feel it vibrating also. It slowly quiets down and after the engine has been shut off for about 2 minutes, the buzzing/vibrating stops. It looks like it says "VAC" on the top, and clearly has at least 2 vacuum lines attached. What is this, and is it supposed to vibrate and emit a loud buzzing sound?

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Old 10-13-2007, 07:22 PM
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Not sure what it is, but mine's out of the car and in a box in the basement now.
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  #11  
Old 10-13-2007, 08:01 PM
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I can't tell for sure without popping the hood again, but it looks like the two vacuum lines are labeled "VAC" and "EGR". See close-up:

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  #12  
Old 10-14-2007, 12:48 AM
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Yep, that's a vacuum transducer. Mine make noise too until the vacuum between it and the device it's controlling bleeds off. Not really sure why they make noise, maybe it's because the diaphragm inside leaks a little.
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http://i52.photobucket.com/albums/g1...MG_2277sig.jpg

1990 300D 2.5 Turbo -155k
2000 E430 - 103k
2014 Jeep Grand Cherokee Ecodiesel 4x4 - 11k
2014 VW Passat TDI SE - 7k Bro's Diesel
2006 E320 CDI - 128k Pop's Benz


Pre-glow - A moment of silence in honor of Rudolph Diesel
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  #13  
Old 02-13-2011, 08:30 PM
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Any transmission/gear shift issues associated with this?

Mine ('84 300SD Turbodiesel, 150K) started making this noise as well... And recently I have trouble moving the gear shifter from drive, through neutral: I meet resistance at Reverse and cannot put the car into Park. I have to go back into Drive for a foot or two, then the gear shift can move through Reverse and into Park.

Are the two issues connected? If not, what might be causing the gear shift issue?
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  #14  
Old 02-13-2011, 09:17 PM
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I believe it is an air transfer.
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  #15  
Old 02-13-2011, 09:35 PM
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Air Transfer

Quote:
Originally Posted by Skid Row Joe View Post
I believe it is an air transfer.
Thanks Joe, would you mind expanding on this?

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