Jerzejeep13
New member
When I shift into 4wd, it is not locking in the front axle. Need help with vac line diagram.
89 Jeep Wrangler YJ
- Thread starter Jerzejeep13
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Jerzejeep13
New member
I don't have locking hubs, it's all done with vaccume
Jerzejeep13
New member
oh ok, I'm not sure what you mean then.,..could u help me out?
Gennybro
Active member
could be the shifting forkis broken,or you have a vacume leak preventing the actuator[shift fork motor] from engageing the shift fork,do yourself a favor and do away with the vacume line and gert a posi lock unit to engage your front axles,quadratec has them.its a cable operated unit that you engauge the front axles with,much more reliable since you havent got too worry about vacume lines deteriorateing with age,or getting a hole in them from some other means and putting you out of action,in the mean time check the area behind your battery and see if a vacume line is there that has gotten battery acid on it and made a hole in the line.
Jerzejeep13
New member
Thanks for the info!!
Jerzejeep13
New member
Thanks!! I will look into that!
Bounty__Hunter
Super Moderator
You have a couple of options. You can try to diagnose why the 4wd light isn't coming on, it's most commonly due to the shift fork in the front axle not locking the axleshafts together. Start by pulling the 2 vacuum ports from the front axle and check for strong vacuum in each port, one for 2wd and one for 4wd.
Or remove the 4 bolts holding the vacuum disconnect to the front axle, slide the shift collar over to lock the axleshafts together, and reinstall the vacuum disconnect upside down. It WILL hold the front axle engaged and you will have 4wd.
Or remove the 4 bolts holding the vacuum disconnect to the front axle, slide the shift collar over to lock the axleshafts together, and reinstall the vacuum disconnect upside down. It WILL hold the front axle engaged and you will have 4wd.
Bounty__Hunter
Super Moderator
Last edited by a moderator:
Jerzejeep13
New member
Thanks so much for all the info.Time to get this fixed.
Both of my vacuum lines are brittle and broken. They are about 1/8" in diameter. Do you know if you can still buy this from Jeep, or do I just need to go to a parts house and try to match up the size.
Don't replace them with the factory junk. If you're going to replace the lines, use some rubber tubing and attach it to the fittings in place of the hard lines.
I did this on my old 88 yj and never had another issue. The old lines would fall apart if you looked at them hard enough. lol
I did this on my old 88 yj and never had another issue. The old lines would fall apart if you looked at them hard enough. lol
Thanks
I fixed the lines but don't have any vacuum on the actuator in 2wd or 4wd. I have engine vacuum going in to the vacuum canister and the line going to the actuator is coming out of a valve mounted on the dash that doesn't appear to have a line going to it. Not sure what Im missing.
Does anybody have a link that will show me a complete vacuum line schematic?
Well, I took it out tonight and drove it about 15 miles and it shut down on me. Not a battery problem, but did not appear to be getting fire or fuel. 2.5 four cyl, fuel injected. I could not detect fire or gas while cranking engine. Can't imagine losing both at the same time. Any ideas what I can check?
Bounty__Hunter
Super Moderator
I'd start a new thread seeking help with the engine problem.
As for the vacuum problem, check for vacuum from the intake manifold to the switch on the transfer case. If there's no vacuum from the switch to the front axle, its likely you need a new switch on the transfer case. The switches are available at most parts stores.
As for the vacuum problem, check for vacuum from the intake manifold to the switch on the transfer case. If there's no vacuum from the switch to the front axle, its likely you need a new switch on the transfer case. The switches are available at most parts stores.
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