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1989 560 SEL
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16 Posts
Discussion Starter #1
Hello,

Recently my 1989 560SEL has hard shifts during driving so I checked the vacuum line attached to the transmission. It was still attached at the transmission but came loose on the other side.

Can someone tell me where it has to be reconnected. Must be somewhere at the intake.

Thanks Mike
 

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Premium Member
2012 CL550 4MATIC Coupe
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10,003 Posts
It's on the intake manifold on the pass side rear. You should see the nipple.
 

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1985 300SD 1988 560SEC 822 1976 450SEL 1981 300SD
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1,078 Posts
A good indication it's past time to do the soft vacuum connectors...they are inexpensive, worth doing the lot..will resolve most lurking vacuum issues..
 

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487 Posts
A good indication it's past time to do the soft vacuum connectors...they are inexpensive, worth doing the lot..will resolve most lurking vacuum issues..
Very correct. That vacuum line from the back of the intake manifold to the transmission is exposed to some SERIOUS heat back there due to proximity to the transverse pipe. If it's not routed correctly and it touches the pipe, the pipe's heat will eventually melt it and create a hole in the tube.

So, when attaching/reattaching the line after replacing it and/or the rubber vacuum connectors at the transmission modulator and at the rear of the intake manifold, be sure to route it correctly so that it is NOT touching the transverse pipe. Ask me how I know ...:eek:

Cheers,
Gerry
 

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1991 560 SEC
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229 Posts
are there 2 vacuum lines to the tranny? one on each side? i thought i saw one on each side when i was down there...
 

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1990 560SEL
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53 Posts
Is there a trick to grasping the smooth plastic line when pulling it onto the new rubber hose connection? The old rubber connection fell off in my hand, so I may have found my vacuum leak. The transmission has been shifting a bit hard, but has been getting better as I fix the other vacuum leaks around the engine bay. The plastic line slipped out of the old rubber connection with zero effort. I have the new rubber hose section on the motor, but am having trouble getting a grip on the plastic hose to pull it on. Any tricks to grasping that line?
 

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Outstanding Contributor
1989 560SEC, 1989 560SEL, 1995 E420
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4,713 Posts
Try holding it with a piece of bicycle inner tube or any thin-gauge rubber for grip. I've also been known to use a pliers when necessary. You can turn the vacuum line 90 degrees and clamp again with the pliers to make the tube round again.
 
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