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Author Topic: Intake Manifold Vacuum Line  (Read 7322 times)

MBdrvr

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Intake Manifold Vacuum Line
« on: November 22, 2013, 05:29:51 »
Hello All,

I am in the process of restoring a '66 250SE Cabrio. After a long time in the paint shop its finally time to put it back together.

I cannot find where the vacuum hose from the intake manifold goes. (See the picture. Not my engine)

Where does this vacuum line connect to?

Thanks,
Paul
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Rodolfo

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Re: Intake Manifold Vacuum Line
« Reply #1 on: November 22, 2013, 07:46:44 »
Is this not just the one connected  to the distributor. (vacuum advance ) Rudy
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Larry & Norma

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Re: Intake Manifold Vacuum Line
« Reply #2 on: November 22, 2013, 09:20:32 »
The hose you have marked in red is the idle air adjustment hose.
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Larry Hall (Gnuface)
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Cees Klumper

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Re: Intake Manifold Vacuum Line
« Reply #3 on: November 22, 2013, 17:44:45 »
Off the top of my head: I think it connects to a tube that is attached to the airfilter canister. I could be wrong though (car 250 kms away at the moment).
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Cees Klumper
1969 Mercedes 280 SL automatic
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1961 Alfa Romeo Giulietta Sprint Coupe 1600
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garymand

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Re: Intake Manifold Vacuum Line
« Reply #4 on: November 22, 2013, 18:48:44 »
Yes, your picture pretty well shows both ends of the hose: one end goes to the Idle Air Valve and the other end goes to the air cleaner.

The air cleaner has a small diameter tube next to the big air oulet to the butterfly valve.  Look closely at the picture and you cn see both ends.
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Gary
Early 250SL German version owned since 71, C320, R350, 89 Porsche 944 Turbo S

garymand

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Re: Intake Manifold Vacuum Line
« Reply #5 on: November 22, 2013, 18:50:16 »
Looks great BTW!
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Gary
Early 250SL German version owned since 71, C320, R350, 89 Porsche 944 Turbo S

wwheeler

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Re: Intake Manifold Vacuum Line
« Reply #6 on: November 22, 2013, 20:41:50 »
As others have said, this is the air supply hose for the air screw. It is in different places depending on your engine vintage.

This screw meters a precise amount of air to the engine at idle. This air screw is adjusted along with the thumb screw on the back of the injection pump to achieve the correct air/fuel mixture.

The reason the hose comes from to the air cleaner is so that it is clean, filtered air. Wouldn't want dirty air in the engine. The WRD valve on the injection pump also has a small filter on it as well. But I digress....
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Wallace
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MBdrvr

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Re: Intake Manifold Vacuum Line
« Reply #7 on: November 22, 2013, 21:51:14 »
Thanks for the information. I'll get the air filter on and set it up correctly.
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Marrs

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Re: Intake Manifold Vacuum Line
« Reply #8 on: November 25, 2013, 23:37:09 »
Quote from: wwheeler on November 22, 2013, 20:41:50
The WRD valve on the injection pump also has a small filter on it as well. But I digress....

This small filter on the injector pump that you reference, in my experience, is almost always neglected as many people don't realize it's there. It's small, cheap, readily available and simple to switch out with a very thin wrench, a tappet wrench is what I had to use. You can test yours by popping it off and attempting to blow through it to see if it is clogged, but I'd suggest replacing it anyway if you don't know when it was last done.
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