91 comache can not get in 4WD


Asked by Dec 13, 2010 at 10:03 AM about the 1991 Jeep Comanche 2 Dr Eliminator 4WD Standard Cab SB

Question type: Maintenance & Repair

I have a 91 Comache with a snow plow it works great until it jumped out of 4WD or 4H it works fine in 2H CAN NOT GET IT INTO 4H N or 4Lo i looked under the car linkage looks fine and moves free what could be the problem.

10 Answers


I do believe that the front axle has a vacume disconnect that went bad or you lost vacuum. Best fix is a manual lock that replaces the vacume parts.


Thanks for the post, I tried moving the lever under the car going into the transfer case, it will not move is your vacuum theory related to that? It feels like to teeth are perfectly aligned and dont allow the gears to mesh? I was told that it could be a broken shift fork inside the transfer case, ever heard of that happening ?

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It would be very hard to break a shift fork in the transcase. Iv never heard of that no. Easy way to tell is pull it in to 4h parked not running and try to rotate the front drive shaft if it spins you have a big problem. If it doesn't its in your vacuum disconnect. Il post a pic for you.

5 people found this helpful.

As you see your passenger axle is a 2 piece axle shaft if the vacuum lines leak the collar will not slide and couple the shafts. The lines on those are known to dry rot from the heat my 92 dakota did the same thing.

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Close up

2 people found this helpful.

Calen Thanks! I will check into this !


Sure gives me something to do for a bit. :) let me know what you find out.


Calen, YOU WERE RIGHT, the shifter was not working and i tried to lock the fork in place so the splined colar would be engaged 100% of the time, remember this is a snow plow just for my drive way. That worked for about 10min then it broke the fork on the shaft it slides on and i was back to not having 2H. I then fabricated a plate with a fork out of solid metal and bolted that in place of the fork housing. a bid crude but it works like a charm. Thanks for the tip and advise with pictures very cool!!


Shweet! If you ever replace it get a manual one :) but I do understand its a plow truck since I live in Montana haha If it was mine id find a single piece shaft from a wrangler or cherokee and eliminate that mess.


They can be turned into a cool truck.

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