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1992 Mercedes Benz 300D 2.5L Auto 168,000 miles and counting
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76 Posts
Discussion Starter #1
I am having a blend door issue. My middle vents do not work now. They worked just fine till i had to replace the Thermostat. Also no the car feels very slugish to and a loss of power is causing concern. I need help :bowdown:
 

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1977 300D
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488 Posts
I am having a similar problem with the same car. My middle vents only start working when the car has been running for a while and has gotten up to speed. I'm thinking it's a vacuum issue, but I don't know where to start.

MW

Edit: There is a known vacuum issue with my car, I just don't know how to solve it. I asked about it in a previous thread, but no one could really give any suggestions on how to fix it.
 

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1992 300ce, 3.0, 207,00 mi.
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335 Posts
The vacuum pods (actuators) controlling the blend doors are a common failure item in these cars. The only problem is it requires disassembly of the entire dash to replace this particular pod. A hell of a job even for the most experienced DIY and cost prohibited for some else to do it. So the best thing to do, as I and many others have done, is to remove the center vent assy, reach in and open the blend door and wedge a piece of rubber hose to keep the door permanetely open. Reinstall the vent assy and control the air flow with the vent adjustment, (usually closed when calling for heat and open for fresh air vent and a/c.
Good luck.
 

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2013 E350 sedan, 2013 E350 cab, 1993 400E sold,1999 ML320
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2,436 Posts
Yep that pod is on the top and can not be reached any other way.

But there is hope. The vacuum manifold to those pod is on the passenger side in the dash behind the glove box/airbag. remove and put vacuum on them. if it works then its the vacuum itself or a sensor.

The sampling valves that draw air in to test temp inside is on the opposite side of the vacuum manifold and should be replaced as they cause some of the issues your talking about (cant tell what temp, must me cold shut that vent kinda thing).

Hope this helps, by the way im replacing my sampler this weekend same issue.
 

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1992 Mercedes Benz 300D 2.5L Auto 168,000 miles and counting
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76 Posts
Discussion Starter #5
:rolleyes:

I found a few unpluged vacuum lines and reconnected them now it runs better and center vents work. Over heating is still going on I think its the lower radiator hose and I will change it and update this blog.

:bowdown:
 

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1992 Mercedes Benz 300D 2.5L Auto 168,000 miles and counting
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76 Posts
Discussion Starter #6
:mad: :( :eek: :crybaby2: :confused:
Ok so I now have found out there is a leak in my coolant I do know where but will diag later this weekend.
 

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2013 E350 sedan, 2013 E350 cab, 1993 400E sold,1999 ML320
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2,436 Posts
What do you consider overheating? The red is overheating anything else is usually parts getting ol ie thermostat, blown fuse for aux fans, sensor for aux fans on dryer and intake.
 

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Registered
1992 Mercedes Benz 300D 2.5L Auto 168,000 miles and counting
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76 Posts
Discussion Starter #8
Well my car sprung a leak and as for overheating it got to the red on the thermostat. I looked for a leak after driving it a few miles to my home and no luck spoting the leak. Also I have been wanting to change the glow plugs but i have to remove the intake manifold but I can not seem to get a 6mm allen on a 3/8 drive to some of the allen bolts. What do I need and what do I need to get this stuff done?

:confused::mad::mad::confused:
 

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1983 300SD, 1986 560SEL, 1992 300D, 1995 E320 Wagon
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245 Posts
For those of you out there that see this comment, I posted a long video on how to remove the W124 dash and how to replace the vacuum actuator pods for the climate control.

Just trying to spread the word. Note that there are only 2 PN's left of the 6 PN's that are available from Mercedes or aftermarket. On the dual diaphragm pods you can buy one of the two pods that are available, remove their arms (white plastic just snaps it on), and you can take off the old arm from the old pod and transfer it to the new pod. NOTE: This trick only works on the dual diaphragm pods. Last resort you can get just the rubber diaphragm inside the pod that you can replace at a place called Performance Analysis in Tennessee, although you can't order on their website. You have to call them. Their part numbers for the two different diaphragms are 2010 and 2020. On the W124 and W126, you can use one of their diaphragm on the "center" pod, which is a single diaphragm. They are inexpensive, not sure how long they will be in business from the conversation I had with them. . Get a bunch and store them the rest of your life!
 
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