944 Turbo vacuum line replacement complete detailed writeup!

[TexasBlake]

I know I've said I'd do this for a while now, but I finished my car and I've been so happy driving it, I didnt' feel like doing any writeups.

Well, I finally sat down and finished my vacuum writeup. I will add a little bit more information in the next few days, as far as talking about the venturi delete, stuff like that.

NOTE: This may not work for any other years besides 1986 cars. The vacuum system changes a little bit, so later cars may hold some things true to my writeup, some may not.

Overall, replacing the system is easy. It's long and tedious, may be frustrating (it's a maze). Before you replace your vacuum lines, read over my writeup a ton of times. Print it out. Print out as many vacuum diagrams as you can find. They will all help. Also note that some parts of the article are left out. For exampl, I don't tell you when to attach the throttle body, intake piping, etc. I assume you know how to do all that stuff. This is strictly vacuum line stuff.

As far as I know, no vacuum line replacement writeup is this detailed. There are some out there, so use as much stuff as you can find.



Porssche 944 Turbo (951) vacuum line replacement


Like always, if something I have is incorrect, let me know. blake@texasblake.com

[kdjones2000]

Very nice write up

I found an NA or other hose that worked in place of that molded hose, rather than the Honda version. Either way you need to cut it and kind of force it on.

[TexasBlake]

Originally Posted by kdjones2000

Very nice write up

I found an NA or other hose that worked in place of that molded hose, rather than the Honda version. Either way you need to cut it and kind of force it on.

If you have the part number I'll add that. Did you have to cut it?

[oldass31]

Blake,

Great write-up. Great angle on the pictures, not too far, not too close. Thank you. But a small suggestion if you will:

I suggest that you emphasize the use of fuel hoses and not radiator hoses. There are a lot of oil vapors traveling around here and from what I understand, oil can eat away the interior lining of your typical Autozone radiator hose.

[nize]

well written write up as usual. thanks for sharing.

[TexasBlake]

Originally Posted by oldass31

Blake,

Great write-up. Great angle on the pictures, not too far, not too close. Thank you. But a small suggestion if you will:

I suggest that you emphasize the use of fuel hoses and not radiator hoses. There are a lot of oil vapors traveling around here and from what I understand, oil can eat away the interior lining of your typical Autozone radiator hose.

I wasn't even aware that you could get coolant hose in 5/16" and I worked in parts for 2 years during college.


Now that you mention it, power steering hose would be even more optimal as they are designed to handle oil.

[running_cold924]

good job dude, i'm sort of following this on the how-to venturi delete and already have found 3 vacuum leaks under the intake......old cars, gotta love them!

[TexasBlake]

Originally Posted by running_cold924

good job dude, i'm sort of following this on the how-to venturi delete and already have found 3 vacuum leaks under the intake......old cars, gotta love them!

That's one thing that sucks about the vacuum system on this car. You can't see under the intake manifold. My vacuum lines didn't look that terrible..... the ones that were visible. Whenever I took the manifold off and tried to remove the vacuum lines around the cycling valve and venturi, they cracked, crumbled, fell apart, ripped, just by touching them. They were flaky like dried mud on your shoe.

[wild man]

I have not looked at the writeup, but I don't understand why you are making such a big deal out of replacing vacuum lines. I like to keep things simple. Why not say "just change them", and be done with it?

[TexasBlake]

Originally Posted by wild man

I have not looked at the writeup, but I don't understand why you are making such a big deal out of replacing vacuum lines. I like to keep things simple. Why not say "just change them", and be done with it?

Maybe look at the writeup before you open your mouth.


1. A lot of people do not have the knowledge to replace them. Many people think that "replacing the vacuum lines" consists only of replacing the small diameter tubing. This writeup is to help them out and show them how to do it.
2. Many people will find their vacuum lines to be incorrectly routed by years of half-assed repairs. Almost all the diagrams floating around out there are incorrect. If someone's vacuum system is currently incorrect, "replacing it" will keep it incorrect.
3. My writeup shows you how to replace the $400 vacuum manifold for $15
4. My writeup shows how to change the venturi system to the venturi delete system.

Thus simply saying "replace them" isn't what my writeup shows, nor is it the end-all approach to replacement of the vacuum system.

I am making a big deal out of replacing vacuum lines because vacuum lines are absolutely essential to the workings of the turbo system.

Why did Porsche create a six volume factory service manual set? Why didn't they just issue all of the dealerships a piece of paper that says "replace it" whenever something on the car fails?

[wild man]

Originally Posted by TexasBlake

Maybe look at the writeup before you open your mouth.

I thought you might say that. But at the time, I hadn't had my coffee yet. And knowing that these cars make very extensive use of vacuum lines, even at THIS time, I'm going to have to decline on looking at it, for reason of fear of being intimidated by how much of a job it really is, once you break it completely down. Being as lazy as I am, I fear that if I look at the writeup, that will lessen the already low probability that I will ever contemplate commencing the undertaking. But I need to face the fact that sooner or later (preferably later) it IS going to need to be done, as we all know that rubber does not last forever. So in light of that, I am thanking you (in advance) for creating a writeup that I might "possibly" need to refer to at some point in the future. I just have way too many other issues that need to be delt with right now, to be worried about replacing vacuum lines. I understand what you are saying about possible routing errors by PO's. But I have made sure that they are routed per what is shown in the service manual, which I am "assuming" is correct. I don't actually know for a fact, that that assumption is a correct one.

P.S. Before you get on my ass about it , now that I think about it, there IS an error that I am aware of, in the service manual vacuum diagram. If I recall correctly, it fails to show the return line coming off of the cycling valve, feeding back in to the intake tree (J-boot).

[TexasBlake]

Originally Posted by wild man

P.S. Before you get on my ass about it , now that I think about it, there IS an error that I am aware of, in the service manual vacuum diagram. If I recall correctly, it fails to show the return line coming off of the cycling valve, feeding back in to the intake tree (J-boot).

It does show that. It's just not very well explained. I just say it goes to the vacuum manifold.

Use some 5/16" fuel line to run this line. It goes from the J-Pipe to the metal tube on the vacuum manifold.

[wild man]

That's funny. The factory diagram that I have only shows 2 lines going in/out of the cycling valve (boost control solenoid valve), when the reality of it is that there are 3. And it is just a diagram - it does not explain anything.

[andruuu]

Thanks for another nice write-up

[wild man]

Now I am totally confounded (if that's proper use of the word). The factory diagram that I just looked at DOES show the 3rd line on the boost controller:



Here is the one that doesn't show it, but I penned it in (you can tell because it it not a perfectly straight line, like the others are). That's the diagram that i though was the factory one, but apparently it is not. At this point I'm not sure where it came from.

[TexasBlake]

Originally Posted by wild man

Now I am totally confounded (if that's proper use of the word). The factory diagram that I just looked at DOES show the 3rd line on the boost controller:



Here is the one that doesn't show it, but I penned it in (you can tell because it it not a perfectly straight line, like the others are). That's the diagram that i though was the factory one, but apparently it is not. At this point I'm not sure where it came from.

That line is the last step of the write up. It goes from the downstream intercooler charge pipe to the cycling valve/waste gate.

Use 5/16" fuel line to run this line from the vacuum manifold to the charge pipe. This is also the line that you would replace with a boost enhancer, if you decide to go that route.

More explanation from Lindsey Racing:

First, let’s explain the basics of turbo charging. Since a turbo is an exhaust driven device, the more pressure you build in the exhaust system, the faster the turbo spins up and the less lag time there is. Keep in mind that the typical turbo spins over 50,000 rpm at full pressure. The turbo takes time (lag) to reach this speed so the more exhaust pressure we can put to it, the faster it will reach the necessary rpm to produce full boost.

The waste gate is the device that regulates the speed of the turbo, otherwise with enough pressure the turbo would over-rev. This is a bad thing! There is a diaphragm in the waste gate that contains the pressure and opens an exhaust valve inside that relieves excess exhaust gas pressure to slow the turbo down. This basic concept is used on virtually all turbo charged applications. The waste gate has a connection to the intake system that feeds boost pressure to it. This is the basics of how the system works. The “Banjo Bolt” on the boost tube is where this connection to the waste gate takes place.

The diagram you are using is somewhat hard to follow because it doesn't show the vacuum manifold as a complete "part" it explodes all the vacuum lines as separate.

[wild man]

Originally Posted by TexasBlake

That line is the last step of the write up. It goes from the downstream intercooler charge pipe to the cycling valve/waste gate

I hate to keep playing the devil's advocate with you (although it does usually make for interesting reading), but that is incorrect. The one going to the charge pipe is a RED line, NOT the black one that I penned in on the 2nd diagram that I posted. I think that diagram must have come from clark's or the water cooler, or some similar site like that.

[TexasBlake]

Originally Posted by wild man

I hate to keep playing the devil's advocate with you (although it does usually make for interesting reading), but that is incorrect. The one going to the charge pipe is a RED line, NOT the black one that I penned in on the 2nd diagram that I posted. I think that diagram must have come from clark's or the water cooler, or some similar site like that.

The black line is this one. I Thought you were talking about the red line.





Like I said, there are many diagrams are there that are wrong. I used the PET mostly. It's much easier to follow:

[wild man]

No problem. The reason I won't look at your write-up now is because I'm afraid that it will make what I now think would be an easy job, look much more involved, thereby decreasing my motivation to ever do it. It's not like I plan on doing it soon, anyways. But if (or should I say when) it becomes a pressing issue, I'll check it out then. At least I know it's there.

[running_cold924]

your going to swap your turbo right? the intake will be already off for that.....it is a "while your in there" thing...