Author Topic: 4WD issues on '96 Montero SR  (Read 476 times)

1941Galant

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4WD issues on '96 Montero SR
« on: December 13, 2018, 04:24:49 PM »
I just got home from a 160-mile trip, and because of a contractor in my driveway, I put the truck in 4WD and tried backing through a small ditch to park off to the side.  I was easily able to get my rear wheels up, and as soon as the front was in the ditch, which required more throttle, the truck made a loud whirring noise in the front, and wouldn't move.  As this happened, the check engine light came on (P1715), and the truck locked itself in 3rd gear.  I cleared the code, took it out of 4WD, and the truck drove fine, and even went back into 4WD without an issue.

I tried replicating the noise in 2WD, with no luck.  It did make a similar noise in 4H while standing on the brakes and hitting the throttle.  I'm guessing this is an issue with the front axle disconnect, but I want to run it past everyone on here since this is my first Montero and I'm still new to the platform. 

Does anyone have any ideas?

Shovel

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Re: 4WD issues on '96 Montero SR
« Reply #1 on: December 13, 2018, 05:01:18 PM »
Sounds like axle disconnect to me.     

It's over 20 years old, you'll want to get in and troubleshoot the whole thing.   Vacuum leaks up by the engine and down below,  the solenoids (they're $20 to replace and take just minutes) ,  lubricate the CAD mechanism. 

Would not be a bad idea to drain the front diff too,  through a discarded white t shirt, cheesecloth, etc to see if you've got glitter in the oil from a potentially long term partial engagement.      The default status of the CAD is connected,  it DISconnects when you put the vehicle in 2wd with the engine running.    The idea there is if it fails 100%, at least it fails in the position where you have more traction not less traction.     The problem with that is if it begins to fail slowly - like a small vacuum leak - it can result in the disconnect grinding on itself for a long time without the driver necessarily noticing.   


1941Galant

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Re: 4WD issues on '96 Montero SR
« Reply #2 on: December 13, 2018, 05:41:57 PM »
Thanks for the info, I'll dig into it this weekend to see what I can figure out.  I've already downloaded the manual, so I'll see if I can find the section on lubricating the CAD.

Shovel

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Re: 4WD issues on '96 Montero SR
« Reply #3 on: December 13, 2018, 07:54:23 PM »
The business side of the CAD is inside the axle housing and lubricated by wash from the diff.   The external actuator is mounted to the rear of the axle tube and has an accordion rubber boot over its moving shaft.    You can pull back the boot and pull the actuator away from the differential case by hand to get grease around the shaft where it is most useful.  Then put the boot securely back in place.

1941Galant

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Re: 4WD issues on '96 Montero SR
« Reply #4 on: December 14, 2018, 06:52:32 AM »
Thanks again for the info, I'll get it in the air sometime today to investigate.  Apparently, my furnace went out yesterday which takes precedence over the Montero.

1941Galant

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Re: 4WD issues on '96 Montero SR
« Reply #5 on: December 14, 2018, 01:59:08 PM »
I was able to grease the actuator shaft pretty well, and I operated it a bunch of times.  I saw the solenoids while I was down there, and I plan on replacing them as soon as I find some part numbers.  I plan on redoing the vacuum lines since I wouldn't be surprised if I am losing vacuum somewhere.

Shovel

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Re: 4WD issues on '96 Montero SR
« Reply #6 on: December 14, 2018, 02:16:22 PM »
Pretty much just any of these

I don't have a DOHC truck to compare with but you can trace the vacuum "source" upstream from the solenoids - on the SOHC trucks it enters a metal tube mounted to the firewall and crosses over to the driver side of the vehicle, then a little 6" long rubber tube connects that to a vacuum nipple on the top of the intake manifold.   

Probably slightly different on the DOHC, but probably not super different. 

1941Galant

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Re: 4WD issues on '96 Montero SR
« Reply #7 on: December 14, 2018, 05:59:47 PM »
Thanks, the part numbers for the DOHC trucks appear to be the same.  I think I'm going to replace those, run some new vacuum line, then pull my boost leak tester out to see if I can find a vacuum leak on this thing.

1941Galant

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Re: 4WD issues on '96 Montero SR
« Reply #8 on: January 27, 2019, 02:45:58 PM »
After replacing the solenoids 4WD works much better.  The truck shifts into and out of 4WD so quickly now.  This weekend it decided it was a good time for the valve stem seals to go, so now I get to tear back into it for that, and new coil pack clips.