4wd shift motor trouble shooting

[WranglerRoller]

RE: mc 2150 crank case vent

:? My 87 Wrangler sounds like it is remaining partially in 4wd when in 2wd. I can shift into 4wd and you can feel the 4wd kick in and the "4WD" light illuminates. When I shift into 2wd the "4WD" light goes out and you can feel the 4wd at least partially disengage. There are a lot of clanking sounds at low speeds coming from the front end. When I put the Wrangler up on jack stands I was able to put a vacuum pump on the shift motor and get the axle out of 4wd completely. However, when I put the Wrangler back on the wheels and reconnected the vacuum hoses I had the same problem. When I took the Wrangler to NJ state inspection they put the Wrangler on a dyno and the car tried to jump out of the blocks, indicating the Wrangler was in 4wd when shifted to 2wd. I can find no information on how to troubleshoot the shift motor, linkage, or shift vacuum system. Anyone know where I can get such info?

 

[Sparky-Watts]

RE: Nice Jeep Knife

Sounds like you've got a leak in one of the vacuum lines to your 4wd actuator. There are several posts here about either replacing the vacuum lines, the actuator itself, or even converting it to a cable actuated shift. A quick search of "4wd Vacuum Lines" should find what you're looking for.

Welcome to Jeepz!!! Hope you stick around awhile, it's always good to have new Jeepers join us!

 

[Bounty__Hunter]

RE: transmission help

Possibly two different things going on here. A problem with the vacuum disconnect will not cause the Jeep to remain in 4wd and jump off a dyno. The disconnect only engages the two pass. side axleshafts, it does nothing to determine 4wd.

Your transfer case lever is not fully engaged in 2wd or there is an internal problem in your transfer case, IF it's actually still sending power through the front driveshaft when you think you're in 2wd.

The vacuum disconnect is easy to troubleshoot. With the jeep running and in park (neutral and chocked if a 5spd), pull the 2-port vacuum harness off the vacuum disconnect. Have somebody shift the jeep from 2hi to 4hi and back. You should feel equally strong vacuum in each port alternating sides depending on 2wd or 4wd. That's it, it will indicate any problems in your vacuum lines or the vacuum switch on the transfer case.

As for the lurching off the dyno, check the transfer case linkage first and make sure 2wd is fully engaged.

As for the noise in the front axle, check the axle ujoints, and the condition of the splines inside the vacuum disconnect housing.

 

[WranglerRoller]

Thanks guys