streetsnake

It seems there has been a ton of vacuum questions that have come up over the years. I took pics as I disassembled the top end but want to make sure I put things back to how it is supposed to be vs. how it was. Through my countless hours of searching I have come up with 3 diagrams I’m trying to make sense out of. I’d think the sticker on the hood would be the best to utilize but I’m not sure I can quite understand how the lines are to be run based on the diagram. I understand the other 2 a bit more but they seem to be lacking additional info needed. I’ve also included a couple pics as I disassembled that I’m hoping you all can give your thoughts on. Appreciate any help you can provide.




I have a new one of these that have 2 inputs (or outputs)…one from the brake booster and the other going to a new 5 nipple connector. Is this okay to do as it wasn’t like this when I disassembled?

Any idea why this red line is capped? The other line is connected.

streetsnake

I'll bump this and also ask if anyone knows where I may find the appropriate red vacuum line that comes off the EGR valve.

Rob Edwards

Here's a shot of the course of the red vacuum hose from throttle body to thermal valve and then to the EGR valve (brown) and the vacuum control valve to the charcoal canister:

streetsnake

Thanks Rob, do happen to have any other shots of your system? I’m just curious if there are many vacuum t connectors. Also, I wouldn’t suppose you know where I can get some new red hose? I can’t seem to source any. Thx

Rob Edwards

The red hose is part # 999 239 012 80, as far as I know it's NLA new. I believe it's the same as the vacuum hose used for the HVAC systems on the early cars that runs to the heater valve. You might be able to cannibalize an HVAC hose harness from a parts car (?)

Here are a couple of pics of top end vacuum hose layouts from the '78 Minerva blue thread. '78 vs. your '79 but it's essentially the same other than the red three way shown above.



And here's a trio of walkarounds of my '79 engine as pulled from the car and after reassembly, hopefully this provides some helpful angles.

Before #1:



Before #2:



After:

Rob Edwards

And here are the pages from the '78 and '79 Service info guides that are relevant to EGR and the various vacuum systems.

https://webfiles.uci.edu/redwards/pu...2012-13-22.pdf

and

https://webfiles.uci.edu/redwards/pu...2012-13-22.pdf

streetsnake

Thanks Rob. Your engine is stunning. Love it. Quick question. In regards to the red hose, were you saying mine should not have a splitter?

Rob Edwards

If your '79 has the vacuum control valve that sits over on the front of the passenger cam tower, then you DO need the splitter so that the red hose goes to both the vacuum control valve, and the temp switch ("30oC temperature valve")

streetsnake

Hey Rob, where does the red hose and black hose go below, or do they get hooked together?

Rob Edwards

They get hooked together. Honestly I'm not sure if the hose is supposed to be red all the way to the vacuum control valve, or if the red/black connection is correct/original and Porsche did that for serviceability. Need to look at more survivor '79s.

streetsnake

Gotcha. Thank you. I don’t understand why my red hose was plugged and then I had a line running from the carbon canister valve to the throttle body. Hmmm. Thanks again for all the help.

928Tom

Do you remember the size of the vacuum hose you used for those red egr lines?

Rob Edwards

The stock vacuum hose is 6 mm OD, 2.6 mm ID.

928Tom

Thanks!