2004 Jeep Grand Cherokee Front Differential Vacuum Hose Diagram

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4x4 Vacuum Lines & Connectors

Stock FSJ Tech Area

GrandW: Posts: 224; Joined: Mon Aug 20, 2018 6:19 pm

4x4 Vacuum Lines & Connectors

Okay, got the engine up, running and broken in and now am tying to repair the 4x4 lines and can't find the diagram or plastic connectors. The green / red / yellow tubing is 1/8th ID and generally called hard emissions tubing.

Trying to replace that and the plastic connector pictured on the right as I cant get the tubing out of it. Any ideas what the opaque plastic things are called?

Also if there's an obvious place to find the vacumm diagram that fits in the ball, that'd be great. I tried oljeep and googling to limited success. The hard plastic lines (lower right), go through the firewall to the switch.

Thanks.

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1987 Jeep Grand Wagoneer

GrandW: Posts: 224; Joined: Mon Aug 20, 2018 6:19 pm

Re: 4x4 Vacuum Lines & Connectors

Post by GrandW » Tue Feb 05, 2019 6:06 am

Turns out the lack of clarity around the plastic vacuum ball is because it's part of the heater system (TV show claimed it had to do with the 4x4). Now to figure out where the vacuum lines connect.......

1987 Jeep Grand Wagoneer

kansasboy001: Posts: 234; Joined: Tue Jan 31, 2017 1:47 pm

Re: 4x4 Vacuum Lines & Connectors

Post by kansasboy001 » Tue Feb 05, 2019 6:40 am

First of all unless your metal lines are rusted through or something there's no need to replace. As for the other lines simply get rubber vacuum hose the right size and replace them.

1983 Cherokee Laredo. 360/ 727/ np228/ Junkyard 7427 TBI/ Msd ignition

acct21: Posts: 235; Joined: Sun Jan 05, 2014 1:32 pm

Re: 4x4 Vacuum Lines & Connectors

Post by acct21 » Tue Feb 05, 2019 4:19 pm

That vacuum ball supplies the vacuum for 4WD -- at least it does on my '90. As you can see in the picture, there used to be a short section of red plastic line that attached to the vacuum ball. It provides vacuum to the selector switch below the dash. and then you will need to patch/repair/replace the yellow and green plastic lines that run from the firewall to the metal lines going to the transfer case. You will need to run vacuum from the manifold to the vacuum ball.

Here is the entire system removed from a vehicle. All that is missing is the attachment of the red line (vacuum supply to switch) to the vacuum ball. After the metal lines, the plastic line colors change, which is pretty confusing. Here is how they were attached from the factory:

2wd Side: Yellow plastic line to steel line, down to transmission area, to green plastic line, to rear side of transfer case vacuum motor.

4wd Side: Green plastic line to steel line, down to transmission area, to red plastic line, to front side of transfer case vacuum motor.

1990 GW with HD towing package -- everything works! (today, anyway)

GrandW: Posts: 224; Joined: Mon Aug 20, 2018 6:19 pm

Re: 4x4 Vacuum Lines & Connectors

Post by GrandW » Thu Feb 07, 2019 8:44 pm

acct21 wrote:That vacuum ball supplies the vacuum for 4WD -- at least it does on my '90. As you can see in the picture, there used to be a short section of red plastic line that attached to the vacuum ball. It provides vacuum to the selector switch below the dash. and then you will need to patch/repair/replace the yellow and green plastic lines that run from the firewall to the metal lines going to the transfer case. You will need to run vacuum from the manifold to the vacuum ball.

Here is the entire system removed from a vehicle. All that is missing is the attachment of the red line (vacuum supply to switch) to the vacuum ball. After the metal lines, the plastic line colors change, which is pretty confusing. Here is how they were attached from the factory:

2wd Side: Yellow plastic line to steel line, down to transmission area, to green plastic line, to rear side of transfer case vacuum motor.

4wd Side: Green plastic line to steel line, down to transmission area, to red plastic line, to front side of transfer case vacuum motor.

Thank YOU!!! Super helpful. Will pick up the hose this weekend. Hoping to get it in for registration tomorrow and then over to paint this weekend. Got delayed by a power steering leak (needed new o-rings), idle issues (kept cutting out, increased RPMs), and now it has a massive squeal at higher RPMs.

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1987 Jeep Grand Wagoneer

kansasboy001: Posts: 234; Joined: Tue Jan 31, 2017 1:47 pm

Re: 4x4 Vacuum Lines & Connectors

Post by kansasboy001 » Thu Feb 07, 2019 9:15 pm

Here is the vacuum diagram from the 89 service manual. Will be the same from 85 to 91

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1983 Cherokee Laredo. 360/ 727/ np228/ Junkyard 7427 TBI/ Msd ignition

GrandW: Posts: 224; Joined: Mon Aug 20, 2018 6:19 pm

Re: 4x4 Vacuum Lines & Connectors

Post by GrandW » Sun Feb 09, 2020 2:44 pm

Okay, it's been awhile, but progress has been made in many other areas. Circling back to the vacuum on the 4 wheel drive, still stumped.

In this photo, the green lines bracket the hose that go to the vacuum reservoir for the cruise control (CC). Isolating the CC vacuum, it seems to work fine, photo 1.
The red line, that hose goes to the engine where it's supposed to be pulling vacuum, photo 2.
The white line, that hose loops around to the air, and needs to be tight because it pulls vacuum for the vacuum motor which opens airflow, photo 3.
The pink line, that connects down to the 4x4 controls, photo 4 (in this photo I was vacuum testing, but corrected it for full testing)
The yellow circle, best I can tell, that's a one way check valve.

Jacked everything up, when I flip from 2 wheel drive (rear spinning), then switch to 4x4, the front doesn't spin. Any thoughts on where I'm going wrong?

1987 Jeep Grand Wagoneer

letank: Posts: 3497; Joined: Wed Oct 03, 2012 9:16 pm; Location: SF bay area

Re: 4x4 Vacuum Lines & Connectors

Post by letank » Mon Feb 10, 2020 7:01 pm

here is the 86, same as 87

GrandW: Posts: 224; Joined: Mon Aug 20, 2018 6:19 pm

Re: 4x4 Vacuum Lines & Connectors

Post by GrandW » Mon Feb 10, 2020 7:21 pm

letank wrote: ↑
Mon Feb 10, 2020 7:01 pm
here is the 86, same as 87

Oh wow, that is different. Thanks for sharing. Will test this weekend and get back. Thanks!

1987 Jeep Grand Wagoneer

sirrus: Vendor; Posts: 701; Joined: Fri Sep 13, 2019 11:13 pm; Location: Hillsboro, OR

Re: 4x4 Vacuum Lines & Connectors

Post by sirrus » Mon Feb 10, 2020 9:35 pm

GrandW wrote: Jacked everything up, when I flip from 2 wheel drive (rear spinning), then switch to 4x4, the front doesn't spin. Any thoughts on where I'm going wrong?

4wd may need to roll front wheels a little to engage, that doesn't happen when you have it up in the air. Maybe try rotating front wheel by hand a little and see if it'll engage?

Sometimes we reinvent the wheel not to have more wheels but to have more inventors

1988 Grand Wagoneer - AMC 360 with ProFlo4 MPFI, TF727, NP229 and lots of relays and other electric upgrades
2021 JLU Willys EcoDiesel - new shiny toy

letank: Posts: 3497; Joined: Wed Oct 03, 2012 9:16 pm; Location: SF bay area

Re: 4x4 Vacuum Lines & Connectors

Post by letank » Tue Feb 11, 2020 6:00 pm

GrandW wrote: ↑
Mon Feb 10, 2020 7:21 pm
Oh wow, that is different. Thanks for sharing. Will test this weekend and get back. Thanks!

It seems that you have too many hoses from the intake manifold feeding to various connections as far as I can see.

One intake manifold T to the vacuum ball, the 4x4 and the cruise control.

the vacuum ball goes to the heater connection

The other intake manifold feed is for the air filter flappers.

GrandW: Posts: 224; Joined: Mon Aug 20, 2018 6:19 pm

Re: 4x4 Vacuum Lines & Connectors

Post by GrandW » Mon Feb 17, 2020 7:24 pm

Okay, big break through... and now more confusion. The PO had the lines all out of sorts. The vacuum line was hooked up to the bottom of the carb. No idea what that hole does for the carb now though.

Connecting the 4x4 vacuum to the intake manifold, the 4x4 works! Yay. But now there's tons of hose that doesnt make sense.

Anybody have great photos or youtube videos of how there vacuum hoses are hooked up in the back of the carb?

Letank- looks like the set up you shared isnt even on the diagram, so thanks for sharing as otherwise the TSM etcetera doesnt give much.

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1987 Jeep Grand Wagoneer

letank: Posts: 3497; Joined: Wed Oct 03, 2012 9:16 pm; Location: SF bay area

Re: 4x4 Vacuum Lines & Connectors

Post by letank » Tue Feb 18, 2020 12:01 pm

GrandW wrote: ↑
Mon Feb 17, 2020 7:24 pm

Good to read that the 4x4 is working

That white drawning tracing for the metal line on your above pict is misplaced, it is usually part of the heater for the choke high idle speed offloader, the mushroom shape grey piece has 2 hoses, one is connected to the hole at the base of the air horn to the mushroom, the other goes to the heater on the intake manifold below the choke mechanism, and the circuit returns to the choke mechanism both with metal lines... I may find a pict at some point, or try a video...

letank: Posts: 3497; Joined: Wed Oct 03, 2012 9:16 pm; Location: SF bay area

Re: 4x4 Vacuum Lines & Connectors

Post by letank » Fri Feb 21, 2020 4:56 pm

GrandW: Posts: 224; Joined: Mon Aug 20, 2018 6:19 pm

Re: 4x4 Vacuum Lines & Connectors

Post by GrandW » Fri Feb 21, 2020 10:40 pm

Letank - you're the best! Got this hooked up Thank you. Had to rerun most the lines, no idea who the POs mechanic was All the vacuum seems right now. THANK YOU!

Underside of the air filter is the last item that isn't right. Not even sure if it needs be hooked up.

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1987 Jeep Grand Wagoneer

sirrus: Vendor; Posts: 701; Joined: Fri Sep 13, 2019 11:13 pm; Location: Hillsboro, OR

Re: 4x4 Vacuum Lines & Connectors

Post by sirrus » Sat Feb 22, 2020 6:54 am

That thing is temperature controlled valve, referred to as TAC temperature sensor in the diagram above. It controls opening of the blend door, which mixes cold air with warm (from exhaust heat exchanger) for intake.

Sometimes we reinvent the wheel not to have more wheels but to have more inventors

1988 Grand Wagoneer - AMC 360 with ProFlo4 MPFI, TF727, NP229 and lots of relays and other electric upgrades
2021 JLU Willys EcoDiesel - new shiny toy

GrandW: Posts: 224; Joined: Mon Aug 20, 2018 6:19 pm

Re: 4x4 Vacuum Lines & Connectors

Post by GrandW » Sat Feb 22, 2020 8:22 am

sirrus wrote:That thing is temperature controlled valve, referred to as TAC temperature sensor in the diagram above. It controls opening of the blend door, which mixes cold air with warm (from exhaust heat exchanger) for intake.

Ah, thanks! I missed the dashed line circle previously. Can definitely get that squared away today.

Also figured out what this metal line is for. Metal line goes in here below the carb, loops around and feeds into the bottom of the carb, pulling clean air from inside the air filter.

Big wins considering how off the hosing was previously. So glad to have this done and again, really appreciate everyone's help.

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1987 Jeep Grand Wagoneer

sirrus: Vendor; Posts: 701; Joined: Fri Sep 13, 2019 11:13 pm; Location: Hillsboro, OR

Re: 4x4 Vacuum Lines & Connectors

Post by sirrus » Sat Feb 22, 2020 9:45 am

That's part of the choke heater - it draws clean air from outside, sends it through heat exchange in manifold and then to choke spring. You can see the second part(metal tube from manifold to choke) attached to manifold. As spring warms up it opens the choke gradually

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Sometimes we reinvent the wheel not to have more wheels but to have more inventors

1988 Grand Wagoneer - AMC 360 with ProFlo4 MPFI, TF727, NP229 and lots of relays and other electric upgrades
2021 JLU Willys EcoDiesel - new shiny toy

Jguess85: Posts: 62; Joined: Mon Oct 28, 2019 12:02 pm

Re: 4x4 Vacuum Lines & Connectors

Post by Jguess85 » Thu Nov 05, 2020 8:58 am

GrandW wrote: ↑
Thu Feb 07, 2019 8:44 pm

acct21 wrote:That vacuum ball supplies the vacuum for 4WD -- at least it does on my '90. As you can see in the picture, there used to be a short section of red plastic line that attached to the vacuum ball. It provides vacuum to the selector switch below the dash. and then you will need to patch/repair/replace the yellow and green plastic lines that run from the firewall to the metal lines going to the transfer case. You will need to run vacuum from the manifold to the vacuum ball.

Here is the entire system removed from a vehicle. All that is missing is the attachment of the red line (vacuum supply to switch) to the vacuum ball. After the metal lines, the plastic line colors change, which is pretty confusing. Here is how they were attached from the factory:

2wd Side: Yellow plastic line to steel line, down to transmission area, to green plastic line, to rear side of transfer case vacuum motor.

4wd Side: Green plastic line to steel line, down to transmission area, to red plastic line, to front side of transfer case vacuum motor.

Thank YOU!!! Super helpful. Will pick up the hose this weekend. Hoping to get it in for registration tomorrow and then over to paint this weekend. Got delayed by a power steering leak (needed new o-rings), idle issues (kept cutting out, increased RPMs), and now it has a massive squeal at higher RPMs.

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