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Unread 03-21-2013, 06:24 PM   #1
Maine1994ZJ
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NV-249 engaging question

Hey, all!! I'm going to check out another ZJ for my wife to DD. It has a 4.0, 42RE, and NV-249. All with 229K miles.

My question is: If it's working properly, how long should it take the viscous coupling to engage the front axle when the rear axle spins?

I'm planning to run it through some snow to test it out and I was hoping to be armed with knowledge.

Any help is most definitely appreciated!!!!!

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Unread 03-21-2013, 07:05 PM   #2
zarnold
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Quote:
Originally Posted by Maine1994ZJ
Hey, all!! I'm going to check out another ZJ for my wife to DD. It has a 4.0, 42RE, and NV-249. All with 229K miles.

My question is: If it's working properly, how long should it take the viscous coupling to engage the front axle when the rear axle spins?

I'm planning to run it through some snow to test it out and I was hoping to be armed with knowledge.

Any help is most definitely appreciated!!!!!
If it's working correctly, the transfer will be instantaneous. Not sure how you will test that, but I'm sure somebody will know.

What you need to test is the VC itself. To do that first get to operating temp (e.g. drive for 20 minutes or so). Then in a parking lot drive in figure 8's. If you can idle through the 8's your probably OK; if it binds, jumps, hops or you have to give it gas to push it through the 8's your VC is probably already done, or on the way out.
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Unread 03-21-2013, 07:37 PM   #3
Maine1994ZJ
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Quote:
Originally Posted by zarnold View Post
Not sure how you will test that
I was planning on backing it up a snowbank in 4HI to test it. That SHOULD work... In theory anyway

Will definitely do the figure 8s!! Thanks for the tip!!
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Unread 03-22-2013, 10:28 AM   #4
ratmonkey
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At that mileage if it hasn't been replaced its guaranteed to be bad. The 93-95 units don't last 100k and the 96-98 units are toast by 150k.
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Unread 03-23-2013, 06:10 PM   #5
RTLee
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Before you buy:
1: vehicle off, put in drive with emergency brake on.
2: jack up RF wheel.
3: use torque wrench set to 90lbs. Try to turn the wheel (using wrench). If wrench clicks, viscous coupler is bad.
4: walk away if wrench clicks.

Otherwise it's a TC swap or VC replacement. Each is pricey in their own way.

Good luck!!

Edit: source is Identifix and Chrysler service manual. This is how I found out my TC was bad.

Last edited by RTLee; 03-23-2013 at 06:12 PM.. Reason: Sources quoted...
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Unread 03-23-2013, 07:17 PM   #6
Maine1994ZJ
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Thanks guys. I went to see it. Long story, short The woman selling it was a TOTAL PSYCHO!!! I'm traumatized now...
20 minutes of my life I will NEVER get back
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