Replacing all Vacuum Lines with Silicone Hose

WWDiesel · **Posted:** Sun Sep 29, 2019 3:40 pm

Received the Silicone Vacuum Hose I ordered in four different sizes. https://www.siliconehose.com/silicone-vacuum-tubing/

In the process of replacing all the cheap plastic vacuum tubing and old rubber hoses with silicone vacuum hoses.
Plans are to re-route the vacuum straight from the brake booster connection across the top of the engine to the little vacuum reservoir at the turbo modulator.
Dash items will still use original routing but will separate from the turbo supply.
Partly completed and test drive shows some slight improved response time for the turbo with the larger vacuum hose.
More to come on this later....

casm · **Joined:** Sun Jan 29, 2006 5:05 pm **Posts:** 694

WWDiesel wrote:

Received the Silicone Vacuum Hose I ordered in four different sizes. https://www.siliconehose.com/silicone-vacuum-tubing/

In the process of replacing all the cheap plastic vacuum tubing and old rubber hoses with silicone vacuum hoses.
Plans are to re-route the vacuum straight from the brake booster connection across the top of the engine to the little vacuum reservoir at the turbo modulator.

This is pretty much what I did. Ran the hose behind the fuel filter head from the booster, on to the T-fitting at the firewall on the passenger side, then on to the turbo vacuum reservoir. There were a couple of disused plastic mounts under the front valance; zip-tied the hose to them to keep it up as far away from the head as possible. Also, anywhere there was a join, it got a clip.

I'll see if I can't get a photo of the routing over the top of the engine tomorrow. Unfortunately, as I used black hose, there likely won't be a whole lot to see, but the zip ties are fluorescent so should be able to give an idea of how things were run.

Quote:

Dash items will still use original routing but will separate from the turbo supply.

This interests me as I really don't like how the HVAC controls feed from the turbo vacuum line. Definitely looking forward to what you come up with for this.

TURBO-DIESEL-FREAK · **Joined:** Sat Apr 17, 2010 3:29 pm **Posts:** 1167

DEFINITELY following...

WWDiesel · **Posted:** Mon Sep 30, 2019 3:38 am

casm wrote:

This is pretty much what I did. Ran the hose behind the fuel filter head from the booster, on to the T-fitting at the firewall on the passenger side, then on to the turbo vacuum reservoir. There were a couple of disused plastic mounts under the front valance; zip-tied the hose to them to keep it up as far away from the head as possible. Also, anywhere there was a join, it got a clip.
I'll see if I can't get a photo of the routing over the top of the engine tomorrow. Unfortunately, as I used black hose, there likely won't be a whole lot to see, but the zip ties are fluorescent so should be able to give an idea of how things were run.

Quote:

Dash items will still use original routing but will separate from the turbo supply.

This interests me as I really don't like how the HVAC controls feed from the turbo vacuum line. Definitely looking forward to what you come up with for this.

Finished this evening. Plan to test drive later. Silicone hose is MUCH tighter on all the slip on connectors. :BANANA:

Installed "Tee" at brake booster for new vacuum line directly to turbo vacuum reservoir. Black hose is original rubber hose that now only feeds HVAC. I may replace this hose as well with silicone, but will have to order some more hose.

Removed "Tee" on firewall where vacuum line goes inside to HVAC controls. Replaced it with a straight connector. Close quarters to work in! :banghead:

Routed new silicone vacuum hose across top of engine over to connection at vacuum brake booster. Not worried about "Heat" since it is silicone hose.
(2 Pictures)

WWDiesel · **Posted:** Mon Sep 30, 2019 3:43 am

Removed all these old plastic piping and rubber fittings.

casm · **Joined:** Sun Jan 29, 2006 5:05 pm **Posts:** 694

Nice!

Couple of things:

WWDiesel wrote:

Finished this evening. Plan to test drive later. Silicone hose is MUCH tighter on all the slip on connectors. :BANANA:

Yep, I noticed that as well. Frankly, the spring clips that I used were probably overkill, but figured I'd go nuts on it while I was in there since there were so many simultaneous issues trying to be sorted out.

Quote:

Installed "Tee" at brake booster for new vacuum line directly to turbo vacuum reservoir.

OK, mine had a one-way valve at about that spot in the hose routing. Did yours, and, if so, did the tee eliminate it? Any differences? My suspicion is that it's there (mainly) in case of failure at the HVAC line.

Quote:

Black hose is original rubber hose that now only feeds HVAC. I may replace this hose as well with silicone, but will have to order some more hose.

Planning on doing this as well, but have to build up the enthusiasm to crawl under the dash first. That T-fitting on the firewall where the HVAC controls get their vacuum from is no fun to work with, either.

Quote:

Removed "Tee" on firewall where vacuum line goes inside to HVAC controls. Replaced it with a straight connector. Close quarters to work in! :banghead:

If I'm understanding correctly, you're not feeding vacuum to the HVAC controls right now. Is this correct?

And yeah... Trying to fiddle that thing into having all three lines properly connected was not fun.

Quote:

Routed new silicone vacuum hose across top of engine over to connection at vacuum brake booster. Not worried about "Heat" since it is silicone hose.

Ditto re: heat. I mainly just wanted to get the hose up and out of the way so that it would be one less thing to have to wrangle the next time I did something under there that involved the turbo side of the engine.

FWIW, I'm also planning on replacing the main feed from the vacuum pump to the brake booster with silicone, but need to order more hose for that.

Diesel Dan · **Posted:** Mon Sep 30, 2019 10:19 am

Looks good.
I will say todays plastic tubing is many times better than the rubber hose used in the 80s.

TKB4 · **Posted:** Mon Sep 30, 2019 12:19 pm

Looks great !

thesameguy · **Joined:** Sat Oct 01, 2016 8:24 pm **Posts:** 652

I did this several years ago when I got the CRD as most of the factory vacuum lines had fallen off or away - it was a mess. Since most of my cars are turbocharged I always have a mess of silicone in the garage.

I'm not 100% confident I guessed right when reinstalling, so thanks much for all these pictures... when the motor goes back in I will have something to reference!

WWDiesel · **Posted:** Mon Sep 30, 2019 1:51 pm

casm wrote:

Nice!

Quote:

Installed "Tee" at brake booster for new vacuum line directly to turbo vacuum reservoir.

See pictures posted in first post of this thread for reference to all of this.
OK, mine had a one-way valve at about that spot in the hose routing. Did yours, and, if so, did the tee eliminate it? Any differences? My suspicion is that it's there (mainly) in case of failure at the HVAC line.
The only "Check Valve" I found was in the vacuum line where it connected to the plastic tubing transitioning to a rubber hose that connects to the turbo vacuum reservoir.

Quote:

Black hose is original rubber hose that now only feeds HVAC. I may replace this hose as well with silicone, but will have to order some more hose.

Planning on doing this as well, but have to build up the enthusiasm to crawl under the dash first. That T-fitting on the firewall where the HVAC controls get their vacuum from is no fun to work with, either.
Replaced that "Tee" with a straight connector and eliminated the "Tee". And yes it was a PITA to get at. Cut my hand while eliminating the "Tee" at that location!

Quote:

Removed "Tee" on firewall where vacuum line goes inside to HVAC controls. Replaced it with a straight connector. Close quarters to work in! :banghead:

If I'm understanding correctly, you're not feeding vacuum to the HVAC controls right now. Is this correct?
NO, still feed vacuum to the HVAC controls via the original tube but did eliminate the "Tee" fitting where it connected to the plastic tube going through the firewall. Plans are to replace this piping with silicone when I get some more silicone hose in stock. Plan to add a small check (one way) valve in this line as well.
And yeah... Trying to fiddle that thing into having all three lines properly connected was not fun.
Now only have a single straight connector there instead of the "Tee" so there is only two lines connected.
FWIW, I'm also planning on replacing the main feed from the vacuum pump to the brake booster with silicone, but need to order more hose for that.
Not a bad Idea, but it is a pretty robust hard rubber hose I believe it is 3/8" size.

WWDiesel · **Posted:** Mon Sep 30, 2019 11:41 pm

Got the HVAC hose replaced this evening. Discovered there was a check valve inline on the OEM hose. Reused it on the upgraded silicone hose to the HVAC. See picture.
Best news; on a 10 mile loop test drive there was a noticeable and distinct difference in the quickness in turbo response. The second I touched the accelerator the slightest tiny bit, the boost on the gauge responded immediately.
Was able to hit 25 psig boost consistently and hold it while climbing hills and going up inclines while accelerating. :BANANA:

Upon closer inspection of removed parts, I discovered the plastic OEM tubing going to the turbo vane actuator appears to have actually gotten really hot at some point and partly collapsed. It had a small flattened out section. See second picture. Could not tell for sure if it was leaking or not, but it did look like it had some hairline cracks in it. This tubing was located in close proximity to the turbo and exhaust manifold area. :shock:

This was a very cheap and worthwhile mod! Am super pleased with results!

All these plastic pipes, tubing, connectors, and rubber hoses and fittings were eliminated in this upgrade. :-)r

iakj11 · **Posted:** Tue Oct 08, 2019 10:02 pm

This looks like a worthwhile mod! WW, do you have a parts list - tubing sizes/lengths, fittings/connectors?

I'm guessing the issue of where to use each size will be pretty obvious once I get into it.

WWDiesel · **Posted:** Wed Oct 09, 2019 2:00 am

iakj11 wrote:

This looks like a worthwhile mod! WW, do you have a parts list - tubing sizes/lengths, fittings/connectors?
I'm guessing the issue of where to use each size will be pretty obvious once I get into it.

I believe I only used 5mm & 6mm tubing. Mostly 5mm.
I purposely went up in size from the tiny plastic tubing for the hose between the turbo vacuum modulator and the turbo vane actuator.
It made quite a difference in helping boost response to be a little quicker. No lag anymore, boost is instant.

This is the place I ordered the silicone hose from:> https://www.siliconehose.com/silicone-vacuum-tubing/
They are a little bit slow, but the hose was good quality and the best prices I found. They have all kinds of silicone hoses and piping.
I just ordered 10 feet of each size so I would have some left over in case I needed it in the future.

Replacing all Vacuum Lines with Silicone Hose

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