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Access to trans. vacuum line?

 
Old 11-20-2018, 04:27 PM
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Otto Mechanic
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Default Access to trans. vacuum line?

While working on a different project (see Trouble w/galled fuel line) I accidentally knocked the vacuum line from the engine bay to the transmission loose. It's the one that's plastic from the vacuum distributor next to the throttle that connects to a cloth covered line just past the firewall and over the bell housing.

I've done this once before during an intake refresh about 5 years ago and for the life of me I can't remember what I had to do to reconnect it. I can see the disconnected plastic line and I can feel the cloth covered line, but I can't get to it from the bottom (can't even see it) and there doesn't seem to be access from the top. The intake isn't in the way from the top, the exhaust is probably in the way from the bottom.

I don't remember dropping the exhaust to reconnect it, I think I managed to get it done from the top of the engine.

Any hints or experience that might jog my memory would be sincerely appreciated. Why Porsche put that junction in such a difficult location eludes me, especially since it's a loose friction fit on my car ('85 S3).


Thanks,
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Old 11-20-2018, 05:15 PM
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monkez
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Man, I struggled with this for a couple of week-ends (i also have an 85 S3). You're right in that this is a **** poor choice on where to place that junction. IIRC, the braided rubber line is only about 3 inches long and connects to a metal line that runs down the center of the car above the heat shield. My issue was that the rubber line was loose and fell off the metal line. There may be a way to reach in, but even my daughters small hands weren't small enough to reach the metal line and connect the hose. In the end, I gave up, bought some high quality silicone vacuum line and ran a new line under the car, all the way to the transmission. Just make sure that the line is kept away from the exhaust and clear of anything that moves. There are some nice, straight metal lines that you can connect the hose to with zip ties that run along the edge on the driver's side.

Initially, I connected the new line to the braided rubber hose above the transmission where the metal line ended . That worked for awhile until I realized the braided rubber hose was old, cracking and causing a vacuum leak. Then it was a matter of getting access to the the transmission and connecting that silicon hose directly. All it really took was some long-handled pliers and some patience.

If you want, I can try to send pictures, but i won't have time until Friday (maybe Thursday after I get the turkey in the oven)

However, I will freely admit that I'm just a hack and there will likely be others with better recommendations. Good luck!
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Old 11-20-2018, 05:30 PM
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Originally Posted by monkez View Post
Man, I struggled with this for a couple of week-ends (i also have an 85 S3). You're right in that this is a **** poor choice on where to place that junction. Good luck!
Well, thanks for confirming this is a true b*tch kitty of a job. I'm trying to close the car up today so I can leave for my mom's, doesn't sound like there's a secret to it and I won't have time to run a new line all the way back this afternoon so I'll probably seal up the intake and call it a day.

Regards,
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Old 11-20-2018, 05:45 PM
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I did it on my 83. Just need to move the heat shield over and use long needle nose plyers and good flashlight to see it. I used new vac hose from auto store. get the longest plyers you can. Fiddly but not bad. Good luck. I forgot to mention that I also unbolted the front cross member and moved over to get a better access.

Last edited by rcrone928; 11-25-2018 at 04:31 PM. Reason: add info
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Old 11-20-2018, 06:14 PM
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Originally Posted by rcrone928 View Post
I did it on my 83. Just need to move the heat shield over and use long needle nose plyers and good flashlight to see it. I used new vac hose from auto store. get the longest plyers you can. Fiddly but not bad. Good luck.
Move the heat shield over? That sounds like it might be a trick. What do you mean?

Thanks,
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Old 11-20-2018, 06:50 PM
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Geo55
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Passenger side heat shield under the car so you can see up on top of the torque tube/ bell housing, Connects to a metal tube. I had to do this also after I got the tt back in.
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Old 11-20-2018, 07:10 PM
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Originally Posted by Geo55 View Post
Passenger side heat shield under the car so you can see up on top of the torque tube/ bell housing, Connects to a metal tube. I had to do this also after I got the tt back in.
Great, thanks. So lift the car, fiddle with the heat shield on the passenger side of the firewall from under the car, see if I can get access to the vacuum line?

This would be much better than pulling the whole intake, dropping the exhaust, and running a new silicone line to the tranny.

Regards,
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Old 11-20-2018, 11:04 PM
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Originally Posted by Otto Mechanic View Post
Great, thanks. So lift the car, fiddle with the heat shield on the passenger side of the firewall from under the car, see if I can get access to the vacuum line?

This would be much better than pulling the whole intake, dropping the exhaust, and running a new silicone line to the tranny.

Regards,
Or scrap the stock setup and run a steel line all the way to the engine in the spare clips next to the rear brake line.
One short piece of silicone each end. Leave the old one there until you next remove the trans!

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Old 11-20-2018, 11:22 PM
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Originally Posted by ramcram View Post
Or scrap the stock setup and run a steel line all the way to the engine in the spare clips next to the rear brake line.
One short piece of silicone each end. Leave the old one there until you next remove the trans!
OMG! That's beautiful! A bit more than I'd bargained on doing this month, but stunningly beautiful. Great work!

Regards,
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Old 11-23-2018, 06:59 PM
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Scott, If you can see in ramcrams pic, right above the cross member is where the vacuum line from the engine bay connects to the steel line. I'm pretty sure that I did not have to remove the exhaust from the manifolds, But then I think that you would only have to drop the passenger side to get the heat shield off. The vacuum line should run through a bracket at the top of the bell housing so all should be connected there. If you are trying to get the vacuum line back to the top from there you may be able to pull the line down far enough to slide a piece of pliable wire down from the top and push it into the vacuum line and pull it back up. Good luck!
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Old 11-24-2018, 11:19 AM
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Iíve had to replace the vacuum flex hose between the rigid vacuum pipe (above the torque tube) and the vacuum distributed in the engine bay several times. I have large hands and could manage it without too much issue. Thereís nothing wrong with the stock setup. You need to have the car up high enough to work underneath so that you can see and/or feel the end of the rigid pipe. You may have to remove the pass side heat shield (easy couple of bolts). Use silicon high temp flex hose and try to have sufficient length/slack to keep the hose away from the exhaust pipe.
in other words; once you are under the car and can see/feel the rigid pipe, you can figure out the means to attach a new flex hose. I didnít need and tools to do this.
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Old 11-24-2018, 02:39 PM
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Originally Posted by ramcram View Post
Or scrap the stock setup and run a steel line all the way to the engine in the spare clips next to the rear brake line.
One short piece of silicone each end. Leave the old one there until you next remove the trans!
That is clever! Next time I am under an A/T car that's exactly what I will do.
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Old 11-24-2018, 10:01 PM
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Scott,

Is the air filter box removed? This happened to me with my 86.5 and I don't remember having that hard of a time reconnecting the hose end back on the steel line at the firewall area.

I do remember removing the air box to see and get at everything at the firewall however.

HTH,
Constantine
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Old 11-25-2018, 01:58 AM
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Originally Posted by Constantine View Post
Scott,

Is the air filter box removed? This happened to me with my 86.5 and I don't remember having that hard of a time reconnecting the hose end back on the steel line at the firewall area.

I do remember removing the air box to see and get at everything at the firewall however.

HTH,
Constantine
Hi Constantine -

Yes, the air box was out (back in now for the duration). The cloth covered line dropped behind the firewall, I'm not sure it's still connected to the steel line but I think I can feel it. I can't get it to poke out into the engine bay again.

Sounds like I may be able to get to it from below by moving the passenger side heat shield.

Regards,
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Old 11-25-2018, 10:43 AM
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Hi Scott,

Sounds like a plan. From memory it is just a slip fit over the steel tubing at the front. I do seem to remember reconnecting it from under the car by feel more than actually seeing it. I also remember putting a small plastic zip tie over the union so it wouldn't come off as easily in the future.

The way I found out my rubber line became disconnected was pronounced shift hardness, to include chirping rear tires when pushed hard. Thought it was because of the weight reduction the 928S (aka "the Coke Car") went through over a year of work. To my chagrin was told it was because of the disconnected vacuum line to the transmission, which I found at the front. This was when the car was still an automatic before the 5-speed conversion.

Good luck with the work!
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