Snapped a vac hose, but engine seems to accel better.. - PeachParts Mercedes-Benz Forum

SGT John · #1 04-06-2007, 06:59 PM

Ok, so I broke one of the hoses connecting to my ALDA earlier today. It's not the one that goes to the crankcase, but the other one.

I drove the thing to go find some hose and it seems it's running better than it has been! What did I break? Should I fix it?

winmutt · #2 04-06-2007, 07:05 PM

That is your ADR (ARD some such nonsense) line that eventually goes back to the turbo itself. Not sure if you should fix it or not

SGT John · #3 04-06-2007, 07:15 PM

Should I plug the alda side? There seems to be suction on the open fitting.

winmutt · #4 04-06-2007, 10:31 PM

Its probably best to plug it. I believe thats a leak in the EGR system as well hence your improved driveability.

bgkast · #5 04-06-2007, 11:05 PM

That hose was leaking on my new '85 causing very bad performance. I plugged the line at the ALDA, but the car seems to shift more harshly now (could be my imagination though). What does that blue thing do anyway?

You should plug the nipple that comes off the ALDA, otherwise you the ALDA will not be recieving the correct pressure signal.

SGT John · #6 04-06-2007, 11:19 PM

bgkast,
My car ALSO seems to be shifting a lot harder now, even though I haven't plugged anything yet. I intend to replace the hose totally. I bought some vac line but I think it might be the wrong size.

bgkast · #7 04-07-2007, 01:40 PM

Good, I'm not crazy!

I think mine just came off where it attaches to the underside of the blue thing. I'll try reconnecting it and post back if the car shifts better.

2.5Turbo · #8 04-07-2007, 02:55 PM

That's the vacuum amplifier.

From http://www.peachparts.com/Wikka/TransVacTune :

"The most important modification came with the 1985 model and is continued on all subsequent ones. It involved the addition of a vacuum amplifier to the system (see Fig. 7). The amplifier takes a large vacuum supply, the proportioning vacuum signal and a boost signal and creates the final signal to the transmission. This device did two things. First, it incorporated the input of boost to further tailor the load control of the modulator vacuum signal. The vacuum at the modulator now starts high - 12-17 in. - and is reduced to about five inches through straight throttle movement. As boost builds, the vacuum is further reduced to zero only at full boost."

bgkast · #9 04-07-2007, 11:00 PM

Quote:

Originally Posted by 2.5Turbo

That's the vacuum amplifier.

From http://www.peachparts.com/Wikka/TransVacTune :

"The most important modification came with the 1985 model and is continued on all subsequent ones. It involved the addition of a vacuum amplifier to the system (see Fig. 7). The amplifier takes a large vacuum supply, the proportioning vacuum signal and a boost signal and creates the final signal to the transmission. This device did two things. First, it incorporated the input of boost to further tailor the load control of the modulator vacuum signal. The vacuum at the modulator now starts high - 12-17 in. - and is reduced to about five inches through straight throttle movement. As boost builds, the vacuum is further reduced to zero only at full boost."

Thanks. No wonder the car shifts so badly now!

TheDon · #10 04-06-2007, 11:18 PM

yea.. the 85's are weird in the anti-air world... surf is always like.. wtf is up with this crap on the 85's when we look under my hood... I want to get rid of all or most of the lines and simplify it all

SGT John · #11 04-07-2007, 04:53 PM

Is there any cleaning I can do on the vacuum amplifier? brake cleaner perhaps, like the switchover valve?

I will be hooking it back up today. The improved performance is gone and I am shifting WAY too hard for comfort and too early in a couple of gears.

300SD81 · #12 04-07-2007, 05:43 PM

Is it possible to retrofit a vacuum amplifier onto an older car?