mystery vacuum connection - anyone identify?

[flagstaff]

took the air cleaner off the other day whilel i was doing a service, and discovered this little vacuum connector on the inlet for #3 cylinder with an open end and nothing connected to it. i plugged it with my finger and presto! the slightly rough idel i have been experiencing just went away. so ... what was *supposed* to be connected to this thing? pics at
www.yeknom.karoo.net
will be most grateful for any illumination 8)

 

[flagstaff]

hm. looks as if this one's gonna remain a mystery :?

 

[mike65]

Hi Flagstaff

I looked at this thread and was'nt sure what you were referring to
but having seen the pix (too big!) you have my full attention cos I have the same little pipe with nothing attachted to it! I'll test the idle, which is abit rough on mine as well tomorrow.

So if there is anyone who DOES know what that pipe is for please tell us both!

Mike.

 

[mike65]

I've just looked at the Haynes manual and no reference is made to the pipe but there is a picture of the throttle body and it shows the pipe apparently plugged! Section 4B.8 picture 10.13.

edit> I took off the air cleaner and put my finger over the pipe and sure enough its a vacum, the tickover became a little smoother but as my car needs its fuel-air mix sorting (I'll do that next week) the benefits may not
be fully aparent.

Mike.

 

[flagstaff]

hm, interesting. the fact that *your* connector also goes nowhere leads me to suspect that this can't be coincidence, and that there isn't supposed to be any connecting tube there. but of course, a hole in the inlet manifold sort of defeats the purpose of having a vacuum there at all. but then you mention that the Haynes manual shows a plug ... which may have fallen out on both our cars? doesn't sound very mercedes-benz ... anyway, if i turn up any further info i will be sure to post back with details.

sorry about the big pictures, we broadband users start to take snappy loading times for granted after a while!

 

[mike65]

The engine in the pic is a 2.3 US spec, spot the pipe at the bottom. I was wondering if the vacum is for something like cruise control? :?

Mike.

 

[flagstaff]

excellent pic mike65! ... but why is the connector there at all? it seems to serve no purpose ... and even if it is supposed to be capped/blocked, surely it would have been more sensible not to have had the rubber connector at all?? man, this thing is driving me crazy :roll:

 

[kiwi_bloke]

not the same car but some enlightenment!!!

Hey, i have a 230e. Im under the impression that the engine in this is the same as the 2.3 in the 190es??

Well, i had a look on my car this morning while trying to track down another problem.

The vaccum connection has a pipe coming from it!!!

a cream pipe with a red line on it. Goes straight down underneath the engine. Sorry, i couldnt work out where it leads to.....

There we go, i hope that helps curiosity get the better of u

 

[kiwi_bloke]

o yep,

thought this might help work out weather its relevent....

engine number is 102 982 62 131974

let us know what happens!!!

 

[andy_k]

I'm gonna take a guess here.....

your 190 is a manual?

I suspect that vacuum feed is for the auto gearbox - as I said just a guess.

Andy K

 

[flagstaff]

nah, it's an auto ... checked all vacuum lines, seems the gearbox connections are all in order. the mystery continues...

 

[kiwi_bloke]

air con?

looking at the haynes manual, i cant really make sense of this damn diagram. But heres a gues.....air con idle by pass??? I had another look on my engine and the vaccum pipe goes straight down then comes toward the front of the engine bay.....

 

[mike65]

If that vacum is part of the inlet manifold then it could be something to do with Exhaust Gas Recuirculation control?

Mike.

 

[MikeC]

I just got my car back from a small garage and I could hear a sucking noise coming from under the air filter. It was from the rubber part of this same pipe being loose. Unfortunately, the other end of the 3 foot plastic pipe was just tucked loosely between a few hoses.

The garage admitted that they'd pulled it when working on the car but had left it as they couldn't figure out where it was supposed to go.

Can someone with a 190E Auto kindly trace this pipe and put us out of our misery?

Thanks

Mike

 

[MikeC]

OK - After searching high and low, I found a home for it.

There's a plastic pipe running across the top of the gearbox which stops on top of the bellhousing and terminates in a rubber jointing sleeve (look down gap a RHS of oil filter). This is what my plastic pipe plugs into I'm sure.

Still have a problem getting access but I think this would explain why my gear changes have been a bit harsh.

Mike

 

[mike65]

Aha! thanks Mike, its a control for the auto changer as andy_k suggested which means flagstaff better get a pipe!. Meanwhile I'll just plug the hole with bluetack....

Mike.

 

[MikeC]

Pipe now reconnected and big change in gearchange smoothness.

Method I used:

Remove air & oil filter
Open up a wire coat hanger and thread it through pipe leaving 5mm sticking out
Get hold of pipe on gearbox and poke wired pipe into rubber sleeve
Carefully withdraw wire
Refit pipe to inlet manifold
Refit oil and air filter

Mike