Mysterious Vacuum Lines

Mysterious Vacuum Lines

MDJEEPER

Senior Jeeper
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Location
Calvert County, Southern Maryland
Vehicle(s)
1986 Jeep CJ

Mostly stock, 258 c.i.d., T-176 tranny, Dana 30 front, AMC 20 rear, Dana 300 t-case, 31x10.50 tires, 2 inch body lift
So, as I was working on my project today I found two vacuum lines that the PO had just capped off.

One is longer and attaches to a tee that's attached to some other lines to the air cleaner.

The second is shorter and attaches to a tee toward the back of the engine.

I also found a round cap thingy just hanging out down by the manifold. It also looks like a vacuum line, but I cannot be sure since it's bundled together with a wiring harness. Should this be hanging there not even capped off??

Oh, and then there are two ports on the air cleaner which currently do not have any thing attached to them.

Any ideas what I should do with these various mysteries?? Perhaps they were meant to be used with a different carb set-up?? I dunno...but they are making me nervous!! :eek:
 
So, as I was working on my project today I found two vacuum lines that the PO had just capped off.

One is longer and attaches to a tee that's attached to some other lines to the air cleaner.

The second is shorter and attaches to a tee toward the back of the engine.

I also found a round cap thingy just hanging out down by the manifold. It also looks like a vacuum line, but I cannot be sure since it's bundled together with a wiring harness. Should this be hanging there not even capped off??

Oh, and then there are two ports on the air cleaner which currently do not have any thing attached to them.

Any ideas what I should do with these various mysteries?? Perhaps they were meant to be used with a different carb set-up?? I dunno...but they are making me nervous!! :eek:

I would be willing to bet it was from so previously re-moved emissions equipment or something. You'd need at least a factory shop manual to positively answer that IMHO. Are any of them sucking air now?
 
So, as I was working on my project today I found two vacuum lines that the PO had just capped off.

One is longer and attaches to a tee that's attached to some other lines to the air cleaner.

The second is shorter and attaches to a tee toward the back of the engine.

I also found a round cap thingy just hanging out down by the manifold. It also looks like a vacuum line, but I cannot be sure since it's bundled together with a wiring harness. Should this be hanging there not even capped off??

Oh, and then there are two ports on the air cleaner which currently do not have any thing attached to them.

Any ideas what I should do with these various mysteries?? Perhaps they were meant to be used with a different carb set-up?? I dunno...but they are making me nervous!! :eek:

The two on the air cleaner is part of your PCV & valve cover breather setup.
 
The two on the air cleaner is part of your PCV & valve cover breather setup.

Hm. No I am really confused because there is a vacuum line going to the PCV value and a much larger hose going to the breather...Where else would it be missing a vacuum line??
 
Hm. No I am really confused because there is a vacuum line going to the PCV value and a much larger hose going to the breather...Where else would it be missing a vacuum line??

There should be a line from the valvecover breather to the aircleaner.
 
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OK...now I am really starting to get confused. Here's a picture of my current set-up. As you can see, there is no line coming out of the oil fill cap, and there is only one line coming out of the PCV valve...

From the diagram, it appears that those two empty spots on the air cleaner are supposed to run to something called the "control vlvs" and something else called the "p/air chk vlv (up)". I just don't know what those are!!
 
At the rear of your valve cover should be a 3/8"? hose going to your air cleaner
 
Last edited:
Longhorns info is maybe geared towards the V8?
The diagram I posted was for 1980-1986 I-6 not Ca.
The i-6 valve cover has two hose/grommet connections on top one by the oil cap the other in back, front is for the pcv the rear filtered air from air cleaner.
 
At the rear of your valve cover should be a 3/8"? hose going to your air cleaner

Roger. Got that. Just not sure what the two empty vacuum lines that are capped are supposed to go to. And that odd looking circular thing down by the manifold...
 
looking at the parts list for emissions it could be a vacumn reservoir.its in the doc section in this forum
 
Roger. Got that. Just not sure what the two empty vacuum lines that are capped are supposed to go to. And that odd looking circular thing down by the manifold...



I will say that the vacumm hose routing on the 6's to be by far the most challenging aspect of the Jeep! Mine being a Ca. 78 model is almost naked compared with the 80's model like you have.
Not sure what your state requires for smog but would appear that much of your stuff is gone?
If no testing req. then you will need to figure out what is really needed and go from there, Like Longhorn implied you need a working pcv system to purge crankcase gasses, vacumm to dist. etc.
The two stubs shown on your air cleaner look like tac for your warm air intake system.
the one with a screw is a vacumm source that was eliminated for?
 
OK...now I am really starting to get confused. Here's a picture of my current set-up. As you can see, there is no line coming out of the oil fill cap, and there is only one line coming out of the PCV valve...

From the diagram, it appears that those two empty spots on the air cleaner are supposed to run to something called the "control vlvs" and something else called the "p/air chk vlv (up)". I just don't know what those are!!

I see it as PVC air in/ EGR TVS.;)
 
I will say that the vacumm hose routing on the 6's to be by far the most challenging aspect of the Jeep! Mine being a Ca. 78 model is almost naked compared with the 80's model like you have.
Not sure what your state requires for smog but would appear that much of your stuff is gone?
If no testing req. then you will need to figure out what is really needed and go from there, Like Longhorn implied you need a working pcv system to purge crankcase gasses, vacumm to dist. etc.
The two stubs shown on your air cleaner look like tac for your warm air intake system.
the one with a screw is a vacumm source that was eliminated for?


That's problem with question, no stock vehicle for reference.
 
That's problem with question, no stock vehicle for reference.

That's exactly the problem! I have no idea what a stock vehicle SHOULD look like, so I don't know what's missing and what is not.

I think it's entirely possible that one of the POs started to strip-off some of the emissions gear, but not all of it. So, that leads me to wonder if part of the engine problems are due to the ECM (which I think is still hooked up) not controlling the engine correctly because some of the stuff is gone?
 

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