what are the 2 vacume lines on my 93 stock air box? | Ford Explorer Forums - Serious Explorations

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what are the 2 vacume lines on my 93 stock air box?


Well-Known Member
June 28, 2003
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City, State
ypsilanti, MI
Year, Model & Trim Level
94 ranger XLT
I want to put in a cold air intake and I don't know what to do with the 2 vacume lines. Can somebody help me out????


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One is a vacuum line (eventually goes to that octopus of vacuum lines on the intake)...

The 2nd one goes from the air box to the heat riser tube.. (the air intake from around the exhaust manifold that ties into the normal air intake). This one is you can jsut remove as once you go to a different filter setup you won't be using the heat risor anyway.


so one line still sucks air in and the other one just sits there. Should I tie them into my new air intake just so they have some where to go or what do I do with them? And what about the tube that goes under the battery that gives air to the stock air box do I just leave it there or should I make a brace so it doesn't rattle around?????????????/

The one that goes from the vacuum T off the intake to the air box needs to be blocked off. You can either block it off @ the T (remove the hose) or block it off at your intake (you won't have teh bimetal valve to hook it to anymore).

The other hose you will just remove, along with the intake looking tube that goes from your exhaust manifold to the air box.

As for the other hoses under your air box, you might as well remove them as they will rattle around and aren't going to be doing much anyway.


why does the one at the T have to be blocked off?

Becuase it normally goes from the T (the big octopus looking thing with all the vacuum lines) to a bimetal valve. If you disconnect it at the airbox and don't plug it then you have a vacuum leak..


what if I put a screw inlet on the new intake and plug it up there? I am clear on what thoes lines do. Willl it be bad if it put the lines in the new intake. I am confused about thoes stupid lines.

The line that pulls vacuume will still be a vacuum leak if you put it into your new intake. It iddn't go into the intake tract on your sock setup. It went to a bimetal valve that would open when cold that would then pull a butterly open to let the heat from the heat riser into the intake. It was not a vacuum leak, which it would be if you put it into your new intake.

As for how you plug it, I dont' use screws, I use golf t's but yes you can plug the line, it doesn't matter.. Heck you could plug both lines right at your intake and it would be find.. I was just trying to say you don't need the lines, one you can remove, the other you just need to make sure doesn't become a vacuum leak.


ok i get it now thanks!

So whats the problem with a vacuum leak?

I've been running a custom intake for a while. Can't remember if I plugged those lines or not, I think I just shoved some e-tape in there and taped arouns it or somethin

Theres alot of suction on that one pipe, i took it off once or twice, or 3 times, or whatever :D. But ive always wondered, theres a pipe that connects to some shield over the manifold. I pulled it off the manifold and just stuck the pipe under the battery holder thinger. Is this safe? Or am i stupid? Right now its basically doing the same as the cold air kit, but yeah is it safe?

or is this something not attempted often:(

An actual vacuum leak is bad.. A vacuum leak means you are letting un-metered air into the system... e.g. the MAS has no idea that air is going into the system so you will be running lean..

The big hose from the heat shield to the intake is called a "heat riser". When those other 2 vacuum lines are connected to the air box, they open a butteryfly valve to allow that heated air into the intake to help the motor warm up faster... Thats all those 2 lines are used for... and remember, only 1 goes to a vacuum source (the intake).. the other goes from the butterfly valve to the bimetal vavle.. If you plug the one from the intake, thats all you "have to" do.