4wd not working on '89 YJ, 4.2L, 5 SPD
- Thread starter Johns89YJ
- Start date
Beefy85CJ7
New member
1052921
look on the right side of your front axle (you can see it from your engine compartment)...there's 3 vacuum lines going to a vacuum motor and a small mechanical assembly which control the four wheel drive hubs in the axle; check the connections of the lines here...usually that does it...but if not you may need a new assembly including the vacuum motor and mechanism...Quadratec.com sells them under $100 and it's a very easy fix if you can turn a wrench.
[addsig]
look on the right side of your front axle (you can see it from your engine compartment)...there's 3 vacuum lines going to a vacuum motor and a small mechanical assembly which control the four wheel drive hubs in the axle; check the connections of the lines here...usually that does it...but if not you may need a new assembly including the vacuum motor and mechanism...Quadratec.com sells them under $100 and it's a very easy fix if you can turn a wrench.
[addsig]
1052922
Its often cracked and leaking vaccum lines...where is bounty Hunter and his diagram when you need them hahah. There are 4 lines coming from the transfercase. 2 go to the front axle disconnect motor, one goes to the intake manifold, and one is a breather hose. Carefully inspect each of the four hoses to see if any are disconnected, cracked, or broken. [addsig]
Its often cracked and leaking vaccum lines...where is bounty Hunter and his diagram when you need them hahah. There are 4 lines coming from the transfercase. 2 go to the front axle disconnect motor, one goes to the intake manifold, and one is a breather hose. Carefully inspect each of the four hoses to see if any are disconnected, cracked, or broken. [addsig]
Bounty__Hunter
Super Moderator
1052971
You had to ask, didn't you :-O Just check all the vacuum lines, make sure they are in good working order.
I'd start by pulling the two attached vacuum lines from the front axle. With the Jeep in neutral/park and running, there should be strong vacuum in one line in 2wd, and the other line when in 4wd. If this isn't the case, the problem is in the vacuum harness or the vacuum switch in the transfer case.
If you have good vacuum in both lines, the problem is in the front axle disconnect assembly. Disassemble it and move the shift fork by hand several times, spraying WD40 into the vacuum ports until everything is clean and moves freely. Reassemble and try it out.
[addsig]
You had to ask, didn't you :-O Just check all the vacuum lines, make sure they are in good working order.
I'd start by pulling the two attached vacuum lines from the front axle. With the Jeep in neutral/park and running, there should be strong vacuum in one line in 2wd, and the other line when in 4wd. If this isn't the case, the problem is in the vacuum harness or the vacuum switch in the transfer case.
If you have good vacuum in both lines, the problem is in the front axle disconnect assembly. Disassemble it and move the shift fork by hand several times, spraying WD40 into the vacuum ports until everything is clean and moves freely. Reassemble and try it out.
1053459
Well, Murphy's law is always the prevailent law with Jeeps. My proble is fixed. The vaccum line off the manifold to the Xfer case was about 1/2 off the hose barb. I pushed it on all the way and now I have 4WD again. Had the same prob once with an '87 S-10 Blazer. I hate vaccum systems! Although, they tend to be cheaper than electronic.[addsig]
Well, Murphy's law is always the prevailent law with Jeeps. My proble is fixed. The vaccum line off the manifold to the Xfer case was about 1/2 off the hose barb. I pushed it on all the way and now I have 4WD again. Had the same prob once with an '87 S-10 Blazer. I hate vaccum systems! Although, they tend to be cheaper than electronic.[addsig]
