Found my vacuum leak! - PeachParts Mercedes-Benz Forum

Tomguy · #1 01-01-2004, 11:32 PM

Well, I guess this would cause her to run rich...
The line that comes from the manifold to go to the door locks also goes to a metal line about 2-3' in length. Mine had no tension on it at all and I pulled it out, seeing that the end was completely dirty with crud (although air still flowed through it). It had a 3" vacuum line on the end of it - but where is it supposed to connect to? I don't feel like crawling under in this weather to find out - so please tell me

Somewhere on the tranny?

psfred · #2 01-02-2004, 10:37 AM

It goes to the vac tank under the left front fender. May or may not hold vac, but at least you can plug the line now -- door locks will only work with the engine running, though.

Pull the splash shield behind the wheel inside the fender and see if you can hook the line back up.

Peter

Tomguy · #3 01-02-2004, 12:38 PM

No no... erm, not that line.
This one is a metal line that goes down the RH side of the transmission tunnel, but I don't know where it ends. I know where all my other vac lines go to (brake booster, door locks, MAP sensor, distributor, etc) but I don't know where this one goes.

Maybe if I explain better? The line comes right off the manifold. The line for the door lock vacuum is a long "bolt" if you will, with a hollow center for the air to travel through, and near the head (on the shaft) it has two other holes (almost as if it were a bolt with a nipple on the end, drilled lengthwise, and then cross-wise just below the head). These 2 holes are surrounded by the metal encasing for this vac line. The line is twisted and curved, pre-bent, and it looks like it should be attatched to the plastic clamps on the transmission dipstick. I did plug it for now...

Any ideas? I can't crawl out now, I just finished work on her for today. The first time she's been run in ~2 weeks and she loved it (at least I did!)

psfred · #4 01-02-2004, 02:01 PM

Transmission vac modulator line, probably just the rubber connector to the modulator missing.

Tranny will shift MUCH smoother when you re-attach. At light throttle most of these shift so smooth you cannot feel it.

Peter

Tomguy · #5 01-02-2004, 03:02 PM

Well that's good to know! I know it's always shifted rather rough - I adjusted the control thrust rod before, and got it a bit smoother, but after readjusting all the linkage to proper values, it shifted like it was a manual on crack!

Right now I'm debating some timing things in my head. Maybe I'll sleep on it. I had it adjusted to about TDC before doing any work on it... well, after I did my stuff, I took it out for a test drive, adjusted the MAP since I was rich beyond belief, drove it some more, readjusted the MAP to a bit richer again, and then checked the timing - I couldn't even find the mark and, when I set it "properly" the dizzy was as far clockwise as it would rotate, and I had set it one tooth ahead so it wasn't like that (at least I thought I did). When I took it out again, it lost the mad power it had and now feels like a granny car

psfred · #6 01-02-2004, 03:19 PM

Timing is a PITA on this car, very very difficult to see the timing marks.

I'd recommend bumping the starter until you can see TDC -- no pin, it's tough -- and make sure you have a good mark on the flywheel.

It's very possible to get one tooth off on the timing, but in that case it won't start, I belive.

Get the timing fixed (5 ATDC with vac if your retard works, 7 BTDC without vac it if doesn't) -- one of the classic performance killers on the vehicle is to set the timing with the vac off. Make it a big gas hungry slug. Make sure you have vac (and the retard works!) if you set to 5 ATDC.

Peter

Tomguy · #7 01-02-2004, 07:05 PM

Peter: I definetly have vac

My door lock system now locks faster than ever before! (since I plugged that line)
I have a silver mark at 5ATDC and, unless the paint moved, that's where it still is.
As for setting it one tooth ahead, in one of my adventures to repair the mechanical advance, when I put the dizzy back on, I adjusted the rotor 1 tooth so that I didn't have to turn the dizzy all the way clockwise to get it at 5.

I think I'll put it back where it was - she MOVED! I didn't burn rubber going around a corner, I melted the tires!

psfred · #8 01-03-2004, 11:04 AM

Tom:

Make sure the rotor is pointed to the correct wire on the distributor when installed and timing corretly set -- if the dizzy is very far off, the rotor will be pretty far from the contact, and the spart won't reliably jump. Usually not a problem, but hey, this is an old car, eh?

Peter

Tomguy · #9 01-03-2004, 01:19 PM

Peter: That's why I wanted to sleep on it, I figured maybe if I went out today I'd see that I missed something stupid like that yesterday! (I wouldn't put it past myself, one time I accidentally reversed wires 1 and 5 and wondered why it was idling rough!)

Tomguy · #10 01-06-2004, 12:47 AM

Oh my god... what a difference!

When I replaced this line, I CANNOT believe how much smoother she shifted! It's like a brand-new transmission! The jerk (although I was able to get it much more subtle, it was still there) is now utterly GONE!

psfred · #11 01-06-2004, 09:55 PM

It's fairly common for the shifts on the 4.5 to be imperceptible to most drivers.

I can tell when mine shifts because the exhaust is so loud....

Peter

Tomguy · #12 01-07-2004, 12:08 AM

Peter: Have you thought about taking the header to a welder and seeing what he can do? Just an idea.

psfred · #13 01-07-2004, 11:29 AM

I have a replacement manifold, but currently have a dead car in the garage taking up my work space (hopefully that will be fixed soon).

Not much hope for this one, it has loose bits in the multiple cracks.

Peter