Talk to me About Vac-Tcases....

[Kimbrough]

What would happen if the vac lines came off while driving a NP229 in 2wd? 4wd?

I bought an '85 Grand Wag today. The owner said the NP229 t-case popped as he was driving it and then went into Neutral - All gears are now Neutral - even Park. I dug around inder the hood and found the vac hoses were all disconnected. I think I know the answer, just curoius what you fellas think.
How do I get this Wag driving again?

[Bob Barry]

The condition you describe wouldn't happen from the vacuum hoses coming loose. Is the dash lever in 2wd or 4wd? If it was in 4wd, see if the transfer-case lever can be moved; if you're lucky, the case may have just popped into neutral. smile.gif If you're unlucky, you've got a blown viscous coupler. :(

[joe]

Originally posted by Kimbrough:
What would happen if the vac lines came off while driving a NP229 in 2wd? 4wd? Nothing...whatever mode the x-case is in at the time of the vacuum line mishap is what the x-case stays in until you fix it and apply vacuum again to get it in/out/2wd/4wd whatever. Vacuum is only used for shifting, not for holding it in whatever mode it's in.

[Kimbrough]

***UPDATE***

While I was farting around the Jeep I noticed a few things. Tell me what you think:

- The jeep is on jack stands i.e., the wheels aren't pulling any load.

- Notice ALL vac lines for the T-case are cut.

- I start her up and put into Neutral. I apply vacuum to the vac motor to go into 4wd with a vac pump. Shifts fine and THAT port holds vacuum fine. Now I'm in 4hi and shift thru Drive and Reverse. Front and rear wheels spinning very well.

- Shift back to neutral and put the vac pump on the top port of the vac motor to go into 2wd. Try to shift from Neutral to Drive and she whines and grinds. Hmmm...
Look at the vac guage and its at zero. TOP PORT DOES NOT HOLD VACUUM.

- Check Tranny fluid and it is VERY LOW. Hmmm...

- Lastly, I lift the t-case and notice the tranny moves on its mount! It slides back and forth about 1-2" on the crossmember...

So I ask you guys - WHAZZUUUP???

[LRRH]

- Notice ALL vac lines for the T-case are cut

well this isn't good!!!!

I apply vacuum to the vac

i'm going to disagree with the Dr. and -joe(two of the smartest guys here!!). with weak vaccuum my friend eagle(NP129, no 4lo) was popping out, or should i say did not have enough vaccuum to get all the way into 4wd, so it would slip back. if we engaged it by manually shifting at the case it would stay in 4wd forever =)

- Lastly, I lift the t-case and notice the tranny moves on its mount! It slides back and forth about 1-2" on the crossmember...

this should be the trans tourque mount. it's a single bolt that holds two rubber bushings. they're pretty common to fail. wasn't to expensive(but i think you'll need to go to the dealer for it :(

[ July 12, 2002, 12:04 PM: Message edited by: LRRH ]

[JeepFreak]

LRRH, are you talking about a NP219 or 229?

[LRRH]

AMC Eagle vehicles came equipped with the same drivetrain as Jeeps(sort of). NewProcess made cases for them that have the same size/shape as NP219/228/229, but contained no 4LO. These cases were numbered NP109/119/129 over the years(80-88) when production of the Eagle ceased. If you look into some Eagle web pages, you will find that many owners who want 4LO will simply bolt in a NP229. The Eagles even had the same vaccuum system shift in the early 80's (had to stop and vac. lock front axle), and after 82 i believe they switched to the 129(thus front axle always engaged). The shift mechanism is identical i believe, as well as most of the vaccuuum specs, etc.

[Kimbrough]

Funny thing. While the Jeep was off, I put the vac pump to the top port again. It held vacuum. When I started the jeep, no vac. Hmmmm...

Anyways, I did notice that when I was in 2wd, the vac motor would not hold a vacuum and the shift lever slowly slipped out of 2wd causing a grinding noise.

I'm gonna get a new vac motor!!!

Anyone know where I can get one???