what hoses go to the vacuum bottles

I have a 1988 jeep Cherokee that I am trying to put a 1995 motor, tranny, tcase, and all the wiring into it. I put the heater core in and then put the heater controls wiring through the firewall and went to connect them I noticed that I have an extra vacuum line that I don't have a place to connect it to. The new vacuum ball that goes inside the front bumper has only one vacuum hole in it. Can anyone help me out by showing me pics of the vacuum line and where they go. I look at the FSM for 93 I couldn't find one for a 95 and it didn't tell me what vacuum line went to the heater control valve and the bumper vacuum bottle.
Any help would be greatly appreciated,
DR

The 95 FSM is no help at all either. It might help if you could describe where the mystery vacuum line originates. Remember the 95 has no vacuum axle disconnect, so if your 88 does, that line will have to be spliced in somewhere. Also, as you're probably aware, but just in case, there is a dead-end atmospheric air line in the axle disconnect system, which just dangles from the firewall.

On my 95, two vacuum lines come out through the firewall. One is black, and tees into the line that goes to the reservoir. The other is gray, and goes straight to the heater control valve.

I got the two that come out of the firewall for the heater controls, the ones that connect to the engine, airbox, and the vacuum bottles. I think you solved the mystery for me because I had the black going to the heater control valve, and the gray one I didn't know where it went. On mine there is a tee but one end has a vacuum cover. There was no vacuum line to it was pushed through a hole in the side of the inner fender to hold it in place. This line led to the vacuum bottle in the bumper.

I just reread you post Matt. There is I think three lines that go to the front axle, but the vacuum lines that go to the axle come from the 88 tcase. Now the 95 don't have the vacuum connection. Is there anyway I connect them to the vacuum from the motor or is that a bad thing. Just thinking about it now wouldn't the axle be engaged all the time then from the vacuum from the motor. If I am thinking correctly the tcase only has vacuum when it is in 4x4 right. Or am I wrong? I never messed with this kind of stuff before. I am just thinking about the time I got the old girl stuck in my side yard because I could get it to go into 4x4 because I popped the vacuum lines off the axle when I fixed the oil gasket back about 2 years.
Thanks for all the help,
DR

ilovjeep said:

I just reread you post Matt. There is I think three lines that go to the front axle, but the vacuum lines that go to the axle come from the 88 tcase. Now the 95 don't have the vacuum connection. Is there anyway I connect them to the vacuum from the motor or is that a bad thing. Just thinking about it now wouldn't the axle be engaged all the time then from the vacuum from the motor. If I am thinking correctly the tcase only has vacuum when it is in 4x4 right. Or am I wrong? I never messed with this kind of stuff before. I am just thinking about the time I got the old girl stuck in my side yard because I could get it to go into 4x4 because I popped the vacuum lines off the axle when I fixed the oil gasket back about 2 years.
Thanks for all the help,
DR

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The Tcase gets vacuum all the time, because the motor in the axle has no spring. It is shifted and held by vacuum in both directions. I don't have currently a diagram for that one, and don't recall the color codes, but it shouldn't be too hard to puzzle out. I think there should be 4 lines to the vacuum switch on the Tcase, two running to the shift motor, another the source which is tapped into engine and reservoir vacuum, and one vent line, which should have a little filter-like gadget at its dead end, and just dangle. A third line from the shift motor goes to the vacuum switch on the fender well, which actuates the "4WD" light.

I didn't write my information down it is aw4, NP231 for both 88 & 95. Does it matter that the 95 tcase doesn't have the vacuum connection on it like the 88 had. I am not to worried about the light, but then maybe I should because I won't know it is out of 4x4 or not. Someone told me that the 4x4 will work just the light will not work. I don't know if he is telling the truth or just BSing me.
Thanks for all the help,
DR

ilovjeep said:

I didn't write my information down it is aw4, NP231 for both 88 & 95. Does it matter that the 95 tcase doesn't have the vacuum connection on it like the 88 had. I am not to worried about the light, but then maybe I should because I won't know it is out of 4x4 or not. Someone told me that the 4x4 will work just the light will not work. I don't know if he is telling the truth or just BSing me.
Thanks for all the help,
DR

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If you don't do something about the axle disconnect, it will not engage 4WD (the transfer case will engage, but the axle won't). You have three choices here that i can think of.

The first, and simplest, would be to open up the vacuum motor, remove the fork, and shim it into the permently engaged position with washers (then of course put the fork back on). Jeepers with disco axles have been doing this for some time when presented with vacuum problems. You'll have a permenently engaged axle, just like the newer ones, though not quite as strong as the single-piece axle shaft. A tiny fuel economy and smoothness penalty is offset by simplicity. Since the 95 TC has an electric switch in it, you can wire that directly to the 4WD light and still have an indicator. You'll need a connector for the TC end, and you can then run a homemade harness up to the existing connections on the fender well that were used by the vacuum switch.

Second possibility, also very simple, might be to hard-plumb the vacuum line for "engage" to the vacuum system. You need to trust that the vacuum motor is really working well and holds vacuum. You could even run the disengage line up into the engine compartment too, and have a very primitive part-time engagement system by swapping lines, allowing you to disengage for long freeway runs etc. You could, as above, wire the switch in the 95 TC to the light. Since the 88 vacuum indicator switch is controlled by the disco motor rather than the TC, it won't be useful here. This might be the best temporary solution if you're reluctant to operate on the disco motor or pressed for time, since all it will require is a few feet of generic hose. If you don't have a light, you'll have to remember to look at the lever, but I suspect that isn't hard to get used to.

The third option would be to replace the switch currently on the TC with the vacuum switch for the older model. I'm pretty sure the hole in the case is the same, but if you have both on hand you can check that. If you have your old TC you could use the switch from it, but a new one is cheap at the dealer: under 20 bucks. If you still have all the plumbing and connectors for it, and your disco motor is known to be good this might be the way to go.

For your purposes I think the first option is probably best, because once done it should never need further attention.

Second possibility, also very simple, might be to hard-plumb the vacuum line for "engage" to the vacuum system. You need to trust that the vacuum motor is really working well and holds vacuum. You could even run the disengage line up into the engine compartment too, and have a very primitive part-time engagement system by swapping lines, allowing you to disengage for long freeway runs etc. You could, as above, wire the switch in the 95 TC to the light. Since the 88 vacuum indicator switch is controlled by the disco motor rather than the TC, it won't be useful here. This might be the best temporary solution if you're reluctant to operate on the disco motor or pressed for time, since all it will require is a few feet of generic hose. If you don't have a light, you'll have to remember to look at the lever, but I suspect that isn't hard to get used to.

If I was to do it this way can I leave the hose connected and leave the axle permanently engaged or will this cause problems. I had only one problem with the 4x4 before that was when I drove on dry pavement (I know you are not supposed to) it would howl and the front diff. oil was gray. I forgot to mention I have the whole 95 xj in my yard. How hard/long will it be to swap front diff.. I am looking to get this fixed right the first time but also I want it back on the road quickly as possible. I believe the oil in in has been changed recently, there is a orange RTV around the diff. cover, but I will check to be on the safe side tomorrow morning.
Thanks for all the help,
DR

I talked to someone about this I can't remember who and what the answer was. If swap the front diff. with the one from 95 into the 88 do I have to swap the rear diff. to or no?

ilovjeep said:

I talked to someone about this I can't remember who and what the answer was. If swap the front diff. with the one from 95 into the 88 do I have to swap the rear diff. to or no?

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Assuming the gear ratios are the same, as they ought to be, there's no reason you can't mix and match diffs. People do this all the time (especially the heavy-duty wheelers who are always on the hunt for 87 tow package XJ's with Dana 44 rears). There is also no reason you should have trouble running with the 88 front engaged, as long as you remember to take the transfer case out of 4WD. That is, after all, how the later ones work. I'd look at overall condition and choose accordingly.

The 95 diff should bolt right in, and you'll get a slightly stronger design, since it does not have the disconnect axle, thus a solid right axle in a solid tube. Be aware that the brakes and rotors are different, so they cannot be interchanged. That's no big deal, since pads and rotors are pretty cheap, but if your 95's brakes are worn or rusted from sitting, don't do the job on a Sunday night expecting to swap parts and wheel it on Monday morning. You should also make sure that you keep an inventory of what parts on the vehicle come from what years, and perhaps even the VIN of the donor vehicle, so that you or a subsequent owner can order the right parts in the future.

good idea about the vin numbers. This is just my DD no trails. that would nice if I could that. What I might do is rig this one up to woek for now and then in the spring swap them. Thanks for all the help. You are the only one that helped me with this problem. DR

ilovjeep said:

good idea about the vin numbers. This is just my DD no trails. that would nice if I could that. What I might do is rig this one up to woek for now and then in the spring swap them. Thanks for all the help. You are the only one that helped me with this problem. DR

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As you have just realized Matthew Currie is one of the best on this forum. You're not the only one to learn from this thread. In my opinion it's good for aspiring gearheads (like clumsy me) to read through as many varying threads/problems as they can. What may not be a problem now may soon be a problem later. Might as well learn early. And at least get an idea, however vague, of terminology and theory for future reference.

Good luck to you, DR. Let us know how it goes.

when I done with the jeep I will write up a full report and gradly post on here "my new home away from home."

ilovjeep said:

when I done with the jeep I will write up a full report and gradly post on here "my new home away from home."

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Uh oh. Sounds like you have the "Jeep bug". You'll know it has bitten you real bad when you start drooling at the tool store and count off parts you need in your sleep. Or maybe that's just me?

yeah I got it big time I am already trying to figure out how to make my own thing up to put a K&N filter on. I don't have $200 or more to buy the kit. I love everything about jeep, working on it, driving it, and everything else.