Hey Guys,

Does anyone know where common vac leaks are on W124's? (Specifically, under the hood, not in the car's interior.)

I'm going over the vac system on my '91 300E to eliminate it as having any influence on a low idle/stall situation.

Thanks for all your input!

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Currently:
1972 350SL Euro 4spd
1973 BMW R75/5
1981 BMW R80GS
1995 FZJ80 with OM606 Conversion In Progress

Any of the hard plastic tubing. It dries out and cracks. One that many miss starts from the valve behind the brake master cylinder and routes under the AC / Heater [ACC] fan box, under the battery and into reservoir in the right front fender.

It can be replaced with any quality vac hose. Be sure to save some of the plastic line to make connectors into the right angle and "Y" hose fittings.

That vacuum line is cheap at the stealerships. Buy a a few metres and replace every thing that you can see. The old stuff goes brittle.

I was wondering if the rubber hoses at the end of the plastic hose are bad.. where can i purchase these hoses?

the rubber T and Y and + shaped connectors are available, some from aftermarket suppliers, some from dealer. the dealer ones are nicer material and molded better. don't lose track of the little plastic orifices (that are in the rubber connectors), if any are installed in your lines. they are more used in the diesel vehicles but there might be some on gassers also. they are colour coded.

there are a few molded hoses for the cold start injector and the idle stabilizer valve, they can get very brittle and leak lots of vacuum. they are found under the air cleaner assembly. don't use the aftermarket versions of these bumpy molded hoses, they are poorly made. the dealer has them and they are not very expensive.

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punkinfair

The rubber vacuum components under the distributor/air mass sensor assembly and those going to and from the ICV are quite hard (impossible) to replace without removing the air mass sensor.

There are also lines going to the ICM (Ignition Control Module on driver fender) that need to be replaced with fresh rubber. The plastic lines can be cleaned inside with carb cleaner. Or replaced with new.

Later models will have EGR vacuum lines too (emissions). Behind right headlight - difficult to access without removing anything - as well as vacuum lines inside driver fender. There is a large (probably heat faded too) valve on the driver fender near the alarm horn that distributes vacuum into the fender and to a reservoir (I think).

Taps to the economy gauge and transmission lines are also common sources of leaks - they tap directly to intake manifold vacuum, which means they get exposed to hot elements.

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http://farm8.staticflickr.com/7271/7...144c3fc1dc.jpg

he vacuum hose i have seen, but on the end of the vacuum hose is a rubber hose which attach to the manifold which is in the shape of 90 degrees.. do i have to go to the dealer to get these.. there is also two or three of them on the passenger side fender. I also see about two or three on the drivers side fender.
I will up load a pic today of the rubbers i am talking about.

In the grand scheme of things; buying vac plastic lines, rubber hoses and elbows are cheep, even from the dealer. From the dealer you'll know you have the correct size not a generic "close fit" and by having replaced them, it'll make it easier to diagnose the cause of a malfunction because you'll have eliminated the vac hose leak problem.

While you're replacing the vac lines, it's an ideal time to test the related components with a MightyVac.

Thank you Bob..

I thought I had a leak on the double Y piece behind the brake booster on my 500E.

The pictures show the rubbish I was given.

The normally sensible parts guy suggested I bend the straight "wings" up...

How does a customer provide feedback to the OEM?

James.

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next question...i was told there is a boot shaped hose below the MAF... i tried to remove the MAF but to no success... can someone give me some advice

With some assistance got it changed found the problem and got it fix... up and running now... Thanks for all the advice and suggestions...