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Replace Plastic Vacuum Hoses with Rubber

315760 Views 77 Replies 37 Participants Last post by  AAARacer
This should cover most 87-96 V8s (302\351); for the I6s (300)s the solenoids are in the same general area, as well as the valves. You can use this article as a basis to replace yours, just keep in mind it will be slightly different.

Parts you'll need:
  • All available from a local autoparts store (except one)
  • Approximately 20' of vacuum hose (5\32")
  • 2 Vacuum T's
  • Patience

To get started, I'll explain what the point of it all is. The EEC (Electronic Engine Control or computer) uses electronic solenoids to send vacuum to valves (in this case, three valves: the EGR, the TAB (next to the SMOG pump), and the TAD (behind the upper intake plenum). The EEC sends a signal to the solenoid and it "opens" the valve to allow the engine vacuum through. The easiest way to understand this is with the EGR.

At idle, the EGR is normally closed; but when you get to highway speeds, the EEC wants the EGR to open. The EEC sends the signal to "open" the valve to let the vacuum through and the vacuum opens the EGR. For a more in depth description of the TAB\TAD systems,
see this post (Thanks WuTang).

The TAB valve works the same way, it either directs the air pumped from the smog pump onward to the TAD valve (we'll get there) or out to nowhere (not used). When the TAB valve directs the air onto the TAD valve, the TAD valve either directs the air from the smog pump down into the catalytic converter, or into the back of the engine. Here's a pic:

You can see the coil, the TAD, TAB, and EVR solenoids (EVR controls the EGR). You can see
the yellow line coming from the TAD solenoid, the pink line coming from the TAB solenoid, and the line coming from the EVR is green; can't see it, but it's there. What you can't see (but when you look at your truck you can) are the vacuum hoses that plug into the bottom of the solenoids. This is where the vacuum is supplied to the solenoids. On the EVR(EGR) solenoid, it goes straight to the vacuum tree (vacuum hook-up on the intake manifold). On the EVR(EGR), the top (green) hose goes straight to the EGR valve, and the Bottom (red) hose goes straight to the intake manifold.

The TAB\TAD valves are a little different, but not much. The only difference is that the red line
(yes, the exact same one that goes to the bottom of the EVR\EGR solenoid) goes all the way over to the vacuum canister on the fender, the vacuum canister stores vacuum for these valves (TAB, TAD). Then there is a black vacuum line coming out of the vacuum canister next to the red line that goes all the way back over to the bottom ports of the TAD\TAB solenoids.
From the top of the TAB solenoid a pink hose is run to the valve right next to the smog pump
(I'll show a pic after this rambling paragraph). From the TAD, there's a yellow hose run to
the TAD valve behind the intake manifold.

Here's a pic of a motor that's pulled, just so you can see where the valves are and such;
but you don't have to pull the motor, lord knows I didn't.

You can see the yellow line going to the "diverter" valve (TAD). You can also see
the “bypass” valve (TAB) (you can't see the vacuum line going there, but when you
look at it on your truck you'll see it), plus the EGR and all that other stuff.

Ok, so now that we have an idea of what goes on, let's get started. To avoid confusion,
only run one hose at a time. We need to replace\rerun the red vacuum line, so take a
piece of vacuum hose and run it from the vacuum tree on the intake manifold to
the vacuum canister.

Run it around the back of the engine (I ran it on top of the passenger side valve cover,
under the upper intake plenum). Plug the hose into the vacuum canister where the red
hose plugged into. Here's an overhead pic of how I have my vacuum lines run, you can
also use this to see how to run new (rubber) lines to the FPR (Fuel Pressure Regulator)
and the MAP (Manifold Absolute Pressure) Sensor. In all my pics I tried to use the most
sophisticated graphic design program known to man (Paint) to help. I tried to keep the
coloring the same as the original colors, with the exception of the MAP sensor and FPR:

Go back to the driver side of the intake, where the solenoids are, and cut the vacuum line
you just ran so you can put a "T" on it and run a very short vacuum line to the bottom of
the EVR\EGR solenoid:

From the T you connect a short vacuum hose to the bottom of the EVR solenoid, Pic:

Then run a vacuum hose from the top of the EVR solenoid where the green line used to be
(see pic above) to your EGR valve. I ran the hose through the hole in the middle of the
intake plenum, and then ran it up to the EGR:

Now go back to the vacuum canister, and run a vacuum hose from the OTHER plug on the
canister(formerly black line) to the bottom port on the 2 solenoids for TAB\TAD. You will
need another "T" so that you can split the hose into 2 hoses, one for each solenoid.
Kind of hard to see in this pic, you can see the white tip of the T, but it'll make sense
when your doing it:

2 hoses coming from the vacuum canister (A.C. stands for After Canister):

After that, run a hose from the top port on the TAD (front of the 2 solenoids) to the diverter
valve behind the intake plenum (originally it was a yellow hose). Here's a pic, I literally
set my camera on the intake plenum, and took a picture behind it; so it's kind of close up:

Almost done!
All that's left is to run a vacuum hose from the top port of the rear-most solenoid (TAB)
to the valve that’s right by the smog pump. This was the hardest part for me, but I have
fat fingers, and truthfully it wasn't that bad; just annoying. Here's a pic, it might be easier
to plug the hose in from under the truck, but I was able to do it from the top.

Here's the solenoids with the TAD, TAB, and the A.C. (After Canister) line:

That’s it for the SMOG stuff, but if you want to completely do away with all the plastic crap,
you can run a new hose from the vacuum tree straight to the FPR (fuel pressure regulator),
as well as a vacuum hose straight from the vacuum tree to the MAP sensor.
Here's some pics of the whole set up, you can see the hoses going to the solenoids:

If you change out the FPR and the MAP hoses, then you can literally take out the plastic
crap so it doesn't clutter up your engine bay, like I did:

That's pretty much it, now you have a rubber vacuum system!

Thanks goes to WuTang for proofreading\ideas, and thanks to Miesk5 for clarification on what
years this applies to and his never-ending knowledge!
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Does anyone know of the tree of the intake manifold? There are 4 intakes. One of mine is capped off. Where do all of them go to?

I know 2 go to solenoids and the other to brake manifold. I think po is capped off or it isn't needed.

VRESER, HVAC, FPR, Brake Booster, (+ my 1990 has one to the Vacuum Cruise Control & Cruise Reservoir, yours does not)

You will not see the Brake Booster vacuum Line on my Bronco as I have Electric Boost Brakes. The remaining ports are capped. Remember, some lines are main intake manifold vacuum lines and some are secondary vacuum from actuators.

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While replacing my factory lines with new silicone lines I found the "black" vacuum line from the charcoal canister in the rear of the intake manifold not attached to anything. From reading through this I'm assuming this is where the black hose should go to.

Now go back to the vacuum canister, and run a vacuum hose from the OTHER plug on the
canister(formerly black line) to the bottom port on the 2 solenoids for TAB\TAD. You will
need another "T" so that you can split the hose into 2 hoses, one for each solenoid.
Kind of hard to see in this pic, you can see the white tip of the T, but it'll make sense
when your doing it:

Is this correct?

And thanks to Booba and everyone else who has contributed to this thread. I have had some idle issues that I haven't been able to figure out. Hopefully replacing all the vacuum lines will cure those issues!
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The line from the charcoal filter is for fuel vapor from the tank. It uses fuel resistant rubber and goes to the Cannister Purge Soelnoid (CANP).

A vacuum from comes from the Intake Manifold tee, to the coffee can vacuum reservoir and then goes out the can to the bottom of the solenoids in parallel. Then the top line on the solenoids go out to the TAB/TAD/EGR.

Here is my 1990 5.8L VECI Label. You should have on under your hood.

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Looking at your pic.s it looks as if you didn't replace your vac lines from the intake manifold to the coffee can. Any reason not to change these along with the other lines?

Vacuum Tree to both Vacuum Reservoirs

Emmisions/EGR Vacuum Reservoir

Cruise Control Vacuum Reservoir
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A vacuum from comes from the Intake Manifold tee, to the coffee can vacuum reservoir and then goes out the can to the bottom of the solenoids in parallel. Then the top line on the solenoids go out to the TAB/TAD/EGR.

This one ^^^^^
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That is the Canister Purge Solenoid (CANP). For emissions, fuel vapors are drawn from the fuel tank and are routed to a Charcoal Element Canister. The charcoal absorbs any liquid fuel and vapors are routed to the Throttle Body (Intake) to be reburned, upon command from the EEC. This is because venting vapors into the atmosphere is a major cause of pollution. The line you refer to is fuel resistant rubber as hydrocarbons will break down silicone and other non-approved materials. In other words, that is a Fuel Vapor Line not a Vacuum Line.

Charcoal Element Canister

Canister Purge Soenoid
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PM Seattle if you have any questions for him, your post will be deleted here.

From the forum rules:
Not trying to willy nilly and just go threw here and delete post or anything. But I have been putting an effort into keeping the Tech Write up section just that, A Write up section It Is to be used as a Reference if your doing the same thing/project.
There are rules for this area that no one/most don't follow, eg.Like If you have a ? You PM the original Poster. not keep posting in the thread. If You need or Feel you have to do that, Go Ask the ? in the noobie tech or the 80-96 tech section. more then likely you will even find the same ? posted many time there already. If anyone"original poster" feels that they just need to keep conversing in the thread ask And Ill move it for ya.

So a lot of threads are going to get cleaned up. Please be supportive of the rules for this area. Thank you All. Remember you all make this section what it is and it has some of the Best write ups of any forum out there.
I bought 1' lengths of the 4mm, 6mm, 8mm, and 10mm lines from siliconeintakes, just to see how well they fit.

The 6, 8, and 10 fit well, but the 4 is too big to fit the smallest vac lines properly. I'm guessing a 2-3 would fit well. How did you guys overcome this?
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I had no issues directly connecting the 4mm silicone lines. I did not reuse any old vacuum line or connectors and connected directly to the appropriate vacuum tree and nipples.

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I believe that your tan vacuum line is actually a faded pink vacuum line that goes between the upper port of the TAB Solenoid and the base of the Thermactor Air Bypass Valve.

Passenger Side

Driver Side

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Guess I should have been more clear. My bad. I did read the first post. If I were to use the silicon hose would I need more than 20 ft? And do I need more than just the 4mm size?
I've got an 86 302, so don't order this exactly, but use it to give you an idea of the variety. This was also used to redo the vacuum in the dash for HVAC (all 1/4"):

  • 9' x 3/8"
  • 40' x1/4"
  • 10' x3/16"
  • 5' x1/4"
Here's a video of mine completed as far as I wanted to go, I ran out of 6mm line so I ordered another 6 feet to finish one last plastic vaccum line from the 4x4 coupling near the EGR solenoids going up to the FI plenum but all the rest fit really well, I didn't have any problems with any of the sizes. The original cost for 4,6,8 and 10mm was $54.00 shipped and $11.00 for extra 6 feet totaling $65.00 but it looks really nice now all Red....thanks Seattle FSB..

I made a mistake calling the EVP sensor an EGR solenoid, my bad...but lol

Good Luck ~ :thumbup
My truck hasn't been driven all that much in the last 6 months or so since it's not a DD anymore, but so far everything has held up fine as far as I can tell. When I did my MAF swap I broke one of the vacuum Ts I used, but that was my fault.
Booba5185, Thanks for the great write up! When I first looked under the hood I was bewildered by what I saw.

SeattleFSB, Thanks for your contributions as well.

Steve83, you didn't contribute to this particular thread, but your Supermotors resources were very helpful as well. I always appreciate the time you have put into that.

Although I liked how you guys ran your vacuum lines through the upper plenum, I decided to mimic the factory routing. My reasoning is I think it would be easier to make an emergency repair if need be. Also, I could pull just about any line and it would be long enough to use for any connection by running it up and over the plenum.

For anybody looking to do this, it was super simple. It took me about 1.5 hours, but I was working slowly and in the dark. I also was very impressed with the hose. I wouldn't chance buying it elsewhere as I can see how thinner walled hose would kink. All said and done, it was worth the time and cost not having to worry about 20+ year old plastic lines. :beer
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I was wondering to see how the silicone hoses are holding up also since this thread is a couple years old.

Anyone else besides booba have anything to report on the longevity of the silicone vacuum hoses?
yo Joe,
My 96, bought new still have original vacuum hoses;
"...The vacuum hoses used in the passenger compartment control circuit are constructed from PVC plastic material. The vacuum hoses used in the engine compartment are constructed of Hytrel. Because of the materials used, the vacuum hoses should never be pinched off during diagnosis to locate a leak. Use Rotunda Vacuum Tester 014-R1054 or equivalent to locate vacuum leaks. A wood golf tee can be used as a plug when it is necessary to plug one end of a vacuum hose for leak test purposes..."
Source: by Ford

1996 Bronco/F-Series Workshop Manual
Mini-Tube Vacuum Hose Service

easure the length of the damaged area of the mini-tube vacuum hose.

Cut a piece of standard 3mm (1/8-inch) ID vacuum hose approximately 25mm (1 inch) longer than the damaged area of the mini-tube vacuum hose.

Cut the mini-tube vacuum hose on each side of the damaged area and remove damaged portion of the mini-tube vacuum hose.

Dip the mini-tube hose ends in Tetra Hydro Furan (THF) or Methyl Ethyl Ketone (MEK). Either of these solvents will act as a sealer for the repair of the mini-tube vacuum hose.

Insert the ends of the mini-tube vacuum hose approximately 9mm (3/8 inch) into the ends of the standard 3 mm (1/8-inch) ID replacement vacuum hose.

Shake the service joint after assembly to make sure solvent is dispersed and vacuum line is not blocked internally.

Test system for a vacuum leak in area serviced.


Vacuum Line (Hose), Mini-Tube Damage Repair in a 92
Source: by JohnMcD348 at
How I fixed my A/C Vac Leak
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Since I took Seattle FSB's suggestion and bought the boost/vaccum kit I haven't had a vaccum problem and it looks great, I chose Red.

I didn't have any problems fit wise using the 4mm it seemed fine to me the only thing I didn't like was the 10mm for the TSB brake booster reroute it seemed to thin or soft so I didn't use if you need to check it out..

Good Luck ~ :thumbup
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Is the vacuum line 5/32'' on the inside of the hose or the outside measurement?
5/32" Internal diameter
I rebuild my vacuum lines using 4mm(5/32) silicon vacuum line I purchased from NAPA. This was probably one of the best fixes I have done to the bronco. Very easy to do and totally worth it. Check my Super Motors for Pictures.
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