Tranny seems to "lock up" when shifting into reverse

[Austin Healey]

Hello all,

I have a '97 AWD Explorer XLT with the 4.0 OHC 6-cylinder engine and 4-speed auto tranny. My wife drove home in it today and said "it won't go into reverse." She had driven to a supermarket about three miles away, and after she finished shopping, she tried to back up and said it made a horrible "stuttering" noise. However, she moved the car forward and then tried again, and it did back up, with weird noises.

I tried in our driveway, and the vehicle moved forward normally in Drive. But when I shifted into reverse and applied a little gas, it felt like a rear wheel had locked up. I thought it might be a stuck caliper issue, or a mis-adjusted parking brake, so I jacked up the rear end and started turning things by hand (with transmission in neutral and parking brake off).

Result: both rear wheels turn normally, forward or backward, with little effort required. When one wheel is turned, the other also turns, indicating the limited-slip diff is working. If I get underneath and turn the driveshaft by hand, it turns smoothly and easily in either direction, and turns the rear wheels forward or backward.

This vehicle has approximately 70k documented miles and was ridiculously over-maintained by the previous owner. The stealer sold her every conceivable maintenance service, including at least one tranny flush. I'm sure it wasn't driven hard.

Having reverse go out is obviously a fairly common problem with these transmissions. But to have it go out at 70k miles?

So here's a question: When other owners with a problem say "no reverse," does it mean they shift into reverse and nothing happens, or they shift into reverse and something seems to lock up (like mine)? And if these are different problems, then what is likely to be mine?

I have NOT yet tried revving hard in reverse to see what happens, since if something is broken, I'd prefer not to break it worse. I did check the ATF level (idling, tranny in Park, per manual) and, if anything, it's overfilled. Any connection? There are no warning lights or codes.

Thanks for all suggestions. And I'm prepared to hear the worst ...

 

[delexploder]

transfer case issue , happend to my 97 when it was still stock , i dropped the case opened it up and found two little plastic guides had become brittle and fell apart , these guides when missing allow the case to slip into a neutral position for lack of a better term , my clue to the t case was the noise it made when in reverse , it sounded like a chain hoist

 

[Austin Healey]

That's a ray of hope! However, in your case, did the transfer case actually lock up the driveline (in reverse or both directions), or just stay in "neutral." I can go forward, but not backward (something locks up).

 

[delexploder]

yes it would still function in forward but reverse was intermittently working and sounded bad , i thought it was the trans at first but the noise made me look closer , i put it up on jack stands and ( this is a bit sketchy ie dangerous ) quickly put it in reverse and slid under the truck enough to hear where it was comming from , i also put my hand on the case and could tell it was the t case

 

[koda2000]

Also, check you brake caliper and caliper bracket bolts on all 4 wheels. They've been known to loosen up and if one falls out the caliper can lock up a wheel going in one direction but not the other (this can even break a wheel rim).

 

[Mbrooks420]

Second the caliper bolts. I had this happen in my last Mounty. Also happened in my moms trailblazer, and she punched a hole in her aluminum rim.

 

[Austin Healey]

Re caliper bolts: yup, been there done that w/ the Explorer (front brakes) -- one wheel locked up. I had rebuilt the front calipers and assumed one of them had gone bad, so I said the hell with it and ordered new calipers.

Then, when taking off the old calipers, discovered one of the bolts was missing, causing the brake pads to lock to the wheel. (All this happened about a month before I lost reverse gear, so I'm hoping there is no cause/effect relationship.)

Anyway, if my problem is broken guides, I assume I've gotta pull the transfer case to fix it?

 

[Austin Healey]

IMPORTANT DIAGNOSTIC UPDATE!!!

Raised all four wheels off the ground, started the engine, and here's what I got:

--normal 4wd "auto" setting: Reverse worked (at idle), but with clunking noises and vibrations from below.

--4wd high: Reverse worked, as smooth as butter.

--4wd lo: Ditto.

AND ... interestingly enough, in both 4wd high and lo, the front wheels DID NOT TURN.

So, am I correct in concluding this is a transfer case problem, not a transmission problem? And, is there any diagnosis I should be doing before pulling the transfer case? I know the electric motor on the case is working, but is there a way to tell if it's "throwing" the correct distance?

 

[delexploder]

not really , its either pull and repair or replace

 

[Mbrooks420]

ABS light on?

 

[Austin Healey]

ABS light on?

No ABS light, no warning lights, no codes.

 

[Austin Healey]

Another update: Drained the transfer case and there were little pieces of plastic-like stuff in the bottom of the drain pan. So I'm guessing some kind of gasket or guide failed. Here's a good YouTube video of a guy inspecting a '97 transfer case, pointing out some of the nasty things that happened to it. (He also had a good suggestion: if your case needs a lot of parts, buy a wrecking yard case w/ warranty, take it apart, and see whether it looks good and you should install it, or if you can salvage parts for your own case.)

I got removal half-done today -- disconnecting drive shafts and removing skid plate. (Actually, one of the skid plate bolts would NOT come free, but I was able to pivot the plate to one side, allowing access to the case.)

The big bolts holding the rear drive shaft to the transaxle hub were installed with thread locker, so it took a BIG breaker bar with a half-inch socket to get them loose. Also, they were unusual bolts with knurled heads that I haven't seen before. A 10mm socket fits, but it has to be the kind with eight corners, not four.

Stay tuned ...

 

[delexploder]

The bolts that hold the case to the tranny can be a pain , i use a 1/4 inch drive ratchet and ratchet wrench , i also start with the top bolts and basically wrap my arms around it while laying under it , once all the hard ones are done i move to the side and do the bottom ones , it has a locating pin and a bit of shaft from the trans so it shouldnt just fall on you

 

[Austin Healey]

Well, just to wrap things up:

Finally got the transfer case out (one of the more unpleasant tasks I've encountered in almost 50 years of shade-tree wrenching). Took it apart, and everything looked fine. Took it to a tranny place, which charged me $260 to tell me everything was fine.

So I put it back in, which required buying a new jack, and found nothing had changed. The drive train was no longer locked up, but there was a rumbling sound and vibrations in reverse.

Then, quite by chance, I was standing outside the vehicle w/ the engine idling and the wheels turning in reverse (yes, it was still on jack stands) and noticed -- out of the corner of my eye -- something moving behind the left front wheel. "That's not right," I thought, so I removed the wheel and found the problem: One of the bolts holding the caliper had FALLEN OUT, and when the brake disc rotated backward, the caliper pivoted on the remaining bolt and sometimes jammed itself into the inside of the wheel, locking it.

Installed a new bolt, with thread locker, and all is well (actually, the transfer case doesn't seem to be shifting into Low range when ordered to do so, but at this point I DON'T CARE!)

Thanks for all the advice during this process to a newbie Explorer owner. This is an excellent forum.

 

[Mbrooks420]

Looks like Koda called it. I figured it was likely.

 

[Mbrooks420]

Are you trying to shift into low with your foot on the brake and in park or neutral?