Vacuum system problems

[offroad_newbie]

RE: TJ Muffler Suggestions?

I have a 1990 YJ with a 4.2L. I bought it knowing that the front axles/hubs didn't lock, I think I have traced it down to two vacuum lines. all of the vacuum lines going to the motor on the front diff are connected, and seem to be in good shape. I have found two lines coming from the direction of the transmission/transfer case, one red, and one blue. the both have what look like filters on them. I just for the life of me can't find where they go, or a good diagram which shows them. I found two connections on the bottom side of the air filter housing, but that doesn't seem to be the right place to me. Anyone have a similar year know where they go?

 

[GaryMB]

I don't have a yj, but I bet those two lines with filters by the t-case and transmission are breathers. I don't have any experience with automatic hubs, but I would look for vacuum lines on the hubs themselves and trace them to the engine compartment to search for leaks. Hopefully a yj owner with more experience will jump in here and explain how to fix it.

 

[djak12]

The first thing you need to check is if there are two vacuum lines going to the 4x4 housing. This housing is located on the front axil on the passenger side back side. It has a diapham that is bolted to the axil. Check to make sure that they are attached. I do not remenber where they go since I removed mine. If the lines are good then the problem is probally the internal fork. Behind these 4 bolts is a fork that slides the sleeve over the axil to engage the 4x4. If there is any wear on this fork it will not work. The engagement for the sleeve is only about 1/4" so it might not seem like alot of play but any will cause the 4x4 not to engage. When you pull the cover you will loose a little bit of axil oil so make sure you replace it. The new forks cost about $20.00 at a dealer. It is a very poor design but thats what it is.

 

[LRwrnglr]

I'm having the same problem that you are. I cannot locate a diagram for the vacuum lines. there was one on one of the posts earlier and I traced it down but it woulnd't let me open the file. Maybe someobdy who has it could help us out?? I think I'm goin to re-route the vacuum lines and make a different set-up for the front end. Thanks

LR

 

[djak12]

I had the same problem where it kept kicking in and out so I removed the vacuum system and installed the manual system. It worked great until the fork gave out and I tore it apart and found that it is a very poor design to start and if there is any play it will not engage. That is why I am going to be pulling my axils and putting in arb lockers with high strength shafts. If I find my file on the vacuum system I will add it.

 

[LRwrnglr]

Ok before I put my body lift on my 4xd worked fine, the vacuum put into gear and it ran like a horse. but after my body lift theres no vacuum to the front end and the whole system doesnt work. Does putting that body lift on have anything to do with the 4xd not working??thanks

LR

 

[lah2420]

turn signal swith

Try this site.

http://www.geocities.com/yjlaredo240/index.htm

 

[Bounty__Hunter]

RE: Buying a 1999 XJ ... Needing lift suggestions

Just like the diagram on that website shows, the one vacuum line ends near the battery in a vent. The other three from the transfer case are (one) red line to the intake manifold for vacuum source and (two) to front axle to operate the vacuum disconnect.

Quick troubleshooting of the 4wd system on a YJ:
Jeep running and in neutral or park, tires chocked or locked
Unplug the double vacuum plug at the front axle disconnect
Feel for vacuum in each port while somebody shifts from 2wd to 4wd and back
Vacuum should be strong in 1 port for 2wd, in the other port for 4wd

If this checks out fine, the problem is in the front axle disconnect. Remove it from the axle (4 bolts) and move the shift fork by hand while spraying with WD40, around the fork shaft and into the vacuum ports. Reinstall once the fork moves easily.

If you've got no vacuum at the front axle, move back to the transfer case and feel for vacuum coming from the intake manifold. If you gave vacuum to the transfer case in 1 line, the switch in the transfer case is bad. It's what the 4line vacuum connector connects to. Easy to replace.

 

[offroad_newbie]

Thanks for all the help, hopefully I will be able to get it all hooked up, and let you know what happens this weekend. The website looks like exactly what I needed.

 

[_(OIIIIO)_Jeeper]

You said you did a BODY LIFT...how much? On my TJ when they installed the 3" BL I had to get shifter relocation brackets. Is it possible that your shifter(4WD) is not triggering the proper switches? or at the appropriate time? I still have some trouble with it not wanting to stay engaged in 4LO...but I just hold the shifter in place with a bungee..all is well

BUNGEE!..The jeeperz duct tape! :wink:

 

[hi_c]

RE: This Weekend@Super Lift ORV Park

It is possible that a body lift will stretch the vacuum lines too much causing problems. Open the hood and follow the vacuum lines off the front axle. If your YJ is like mine, those lines are bundled in a nice long piece of split-loom (ribbed flexible conduit to protect the lines, split on side to get lines in and out). That line is pinned to the passenger side fenderwell in my YJ. My lift kit stretched these lines and I had to remove the clip that holds it to the fender. I relocated it lower with a zip tie so that it had some slack to droop the axle, but not so much that it could interfere with other moving parts.

Also, when removing the disconnect housing on the axle, it's a good idea to ramp the passenger front tire so that the gear oil is mostly all on the driver side. Otherwise, you will lose some when removing the housing and it can be messy.

Corey

 

[LRwrnglr]

All I have on the YJ is a 1" body and a 2" shackle. it worked fine without the body so I'll try to relocate the vacuum lines and if that doesnt work then ill check the switch in the tcase. I think the problem might be that my red line isnt going from the carb or intake to the tcase, for some reason its on the passenger side. I'll reroute and do the other checks, thanks for the help

Connor

 

[LVRockCrawler]

go with the home made disconnect or go buy the kit - when i got my 89 YJ it looked like the prev. owner let the batter puke on the hard vac. lines and they were all corroded and broken... thats when i took the ride to the bike shop and hardware store - haven't had a problem since... took about 3 hours to do and a bit of nerve but its worth it!
check this site - its what i used - good step-by-step w/pics!
http://home.earthlink.net/~stevenschreiber/cabledis.htm

 

[offroad_newbie]

Thanks again, everyone, I got a 2 foot piece of vacuum line, and hooked it up, and everything worked like a champ.