Help identifying what vacuum tube is missing on intake manifold

ThePaul

ThePaul

New Member
Joined
Apr 25, 2024
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6
Location
Pennsylvania
Hello, about a week ago my jeep started idling funny and eventually would just die off completely while idling. I checked under the hood and found that on the intake manifold I had this exposed nipple and no tube anywhere to be found. With all my research both on this site/forum and in the owners manual I can't for the life of me figure out what tube is supposed to go here and where the other end is supposed to go to. Does anyone here have any idea? I could really use the help as I'd like to get the jeep up and running for all this nice weather we have coming up!
Thanks

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if there was a hose or black plastic tube attached to it you just need to keep looking for it. Could have fallen down low.
 
Zorba said:
He mentioned "vacuum tube", so 6GH8A is what popped into my mind! ;) :D
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I was about to fetch a photo of a vacuum tube, but I thought I had better read thru this first, and sure enough, you beat me to it.

It's still slightly Jeep related, though. The '50s and early '60s CJs would have had vacuum tube radios, if they came with one. And vacuum windshield wipers, too. I had both in my '57 Chevy, and don't miss them at all.
 
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MutantNinjaTJ said:
that is indeed your vacuum port on the manifold and you'll probably find the hose laying on the motor mount below the exhaust manifold
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I've looked around for a while and there doesn't seem to be any kind of hose disconnected anywhere. That's kind of what is confusing me, I find it hard to believe a whole tube just disappeared. Where would the other end hook up to?
 
JEEPCJTJ said:
Man I had to look that up and I don't think what I found would help.

I also should have asked, how long has the PO owned/driven this Jeep? and I should have said, no matter what you don't want that nipple to suck in non-filtered air.
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I have only had it for a couple of years, the previous owner did a lot of work on it. I've only done regular maintenance, this is the first time I've had a problem beyond my own knowledge. As far as I know, it hasn't driven that much with non-filtered air. I plugged it up the first day I noticed.
 
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Is that a 2.5 or a 2.4 ? Giving your Jeep model year and engine size would be helpful to people trying to help you,

edit: So I found in your profile it's a 1997 2.5

It's not too clear in the FSM pic but it looks like a vacuum line goes from there over to the other side of the engine and connects to a check valve for the HVAC.

vacuum line.jpg
 
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B1Toad said:
Is that a 2.5 or a 2.4 ? Giving your Jeep model year and engine size would be helpful to people trying to help you,

edit: So I found in your profile it's a 1997 2.5

It's not too clear in the FSM pic but it looks like a vacuum line goes from there over to the other side of the engine and connects to a check valve for the HVAC.

View attachment 521739
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On my jeep the vacuum supply line that connects to the reservoir (located under my battery) is connected to the side of my manifold as well
 
I watched a video of a guy getting ready to pull a 2.5 motor out. I could see there looks like a metering valve about two inched long coming from that vacuum port in the manifold. From there there is a much thinner vacuum line that goes toward the fire wall. I could not see where that line ends up. It appears to go
either to the other side of the compartment, or into the fire wall someplace. I would find a Haynes manual and look in the 2.5 engine section. You should be able to see where it goes.
 
Now that I look at your pictures again I think it might be the line thin line that goes over the top of your valve cover near the back and then goes to a thicker fitting just below your throttle body. Take a look at that one and see if it is or is not hooked up.
 
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