02 Mounaineer locks up while parking (when turning in reverse or forward)!!!!

[*deepinthawoods*]

I just bought a '02 Mounty with 158k miles. Engine works perfect, transmission shifts smooth, BUT.......it's locking up while I'm parking! Does it when turning at low speeds, either forward or in reverse! Anyone heard of this before? Causes? could it be the rear diff? Excessive wear at pinion bearing race? incorrect diff fluid without friction modifier?...or could it be the transfer case? shift control module? transf. case shift motor?...when going straight in low, med or high speeds, it runs like a champ! no weird noises, no humming diff...I noticed at rear diff, yoke seal started to leak....please help.
Thanks in advance!

 

[imp]

I just bought a '02 Mounty with 158k miles. Engine works perfect, transmission shifts smooth, BUT.......it's locking up while I'm parking! Does it when turning at low speeds, either forward or in reverse! Anyone heard of this before? Causes? could it be the rear diff? Excessive wear at pinion bearing race? incorrect diff fluid without friction modifier?...or could it be the transfer case? shift control module? transf. case shift motor?...when going straight in low, med or high speeds, it runs like a champ! no weird noises, no humming diff...I noticed at rear diff, yoke seal started to leak....please help.
Thanks in advance!

This means when the front wheels are TURNED and not facing straight ahead?

Bad OUTER C-V joint on either the R.H. or L.H. front axle shaft. Rule out differentials, pinion bearing race (Where the hell did you come up with this?), diff fluid, transfer case, module, shift motor (Is this an AWD? HAS NO shift motor, then), etc. You're not pimping us here, are you?

I don't see how PARKING could have any effect on the vehicle's ability to roll forwards or backwards except due to BINDING in one of the OUTER front axle C-V joints. I'd love to be proven wrong here! Would add to my education greatly! imp (unless the streaming part applies).

 

[*deepinthawoods*]

This means when the front wheels are TURNED and not facing straight ahead?

Bad OUTER C-V joint on either the R.H. or L.H. front axle shaft. Rule out differentials, pinion bearing race (Where the hell did you come up with this?), diff fluid, transfer case, module, shift motor (Is this an AWD? HAS NO shift motor, then), etc. You're not pimping us here, are you?

I don't see how PARKING could have any effect on the vehicle's ability to roll forwards or backwards except due to BINDING in one of the OUTER front axle C-V joints. I'd love to be proven wrong here! Would add to my education greatly! imp (unless the streaming part applies).

Yes, when wheels are TURNED, not facing straight ahead.
With "PARKING" I ment while I'm trying to park the truck, not the position of the gear shift lever, sorry if I'm confusing.
It's AWD correct.

Well......those "diagnoses" started to rain on me while I was checking the truck in the parking lot of an Advance Autopart store(bad idea). You know....everybody becomes a doctor when you got hurt...

Don't get me wrong, I'm asking here for help because I believe it's the best place to touch in this case.

I'll be checking the CV axles and let you know any updates.
Many thanks!!!!

 

[imp]

Yer welcome! imp

 

[BlkSquad]

I had a similar situation on my 2nd gen and it turned out to be an issue with the transfer case, pull the front drive shaft and see if it still does it. With the AWD you won't be able to leave it out but that should at least let you know it has to do with the transfer case and not the CVs or differential. Hope that helps.

 

[imp]

Reason I asked if AWD is, if the transfer case viscous coupling is mechanically binding, while front wheels are turned in parking, the difference in speeds between front and rear driveshafts MIGHT be showing up as the binding in the coupling, but somehow it seems unlikely because the front and rear differentials make up for the speed difference between the wheels of each end of the vehicle.

I'm thinking the viscous coupling if mechanically binding, would make noise that would be obvious. Noise was not described by O.P. was it?

So, anyways, the CV joints are the much more easy thing to check. Also, much less expense to fix, both parts and labor, I'd say. Strike out on CV, go further into it then. imp

 

[*deepinthawoods*]

Reason I asked if AWD is, if the transfer case viscous coupling is mechanically binding, while front wheels are turned in parking, the difference in speeds between front and rear driveshafts MIGHT be showing up as the binding in the coupling, but somehow it seems unlikely because the front and rear differentials make up for the speed difference between the wheels of each end of the vehicle.

I'm thinking the viscous coupling if mechanically binding, would make noise that would be obvious. Noise was not described by O.P. was it?

So, anyways, the CV joints are the much more easy thing to check. Also, much less expense to fix, both parts and labor, I'd say. Strike out on CV, go further into it then. imp

Checked the front cv axles, by lifting both wheels at the same time, trasmission in Neutral. Turned by hand the wheels while steering both ways....
and.........NOTHING! CVs are ok, no cracking noise or whatsoever, boots are ok.
I asked a buddy to drive slowly the truck while making sharp turns both ways. I was walking around the truck to check it...
The rear wheels are locking up. Truck makes a little chattering-rattling when locks up....
I'm thinking to change rear diff fluid with 75W-140 and add motorcraft friction modifier xl-3....
Don't know if this will help, but it's a step I must do since I recently bought the truck.

A friend told me he had a similar issue on a Tahoe with rear posi, and changing the fluid with the correct one fixed it....hope this time work the same!

Yes, my Monty has a rear posi, the id tab says "3 L 73"

 

[imp]

Checked the front cv axles, by lifting both wheels at the same time, trasmission in Neutral. Turned by hand the wheels while steering both ways....
and.........NOTHING! CVs are ok, no cracking noise or whatsoever, boots are ok.
I asked a buddy to drive slowly the truck while making sharp turns both ways. I was walking around the truck to check it...
The rear wheels are locking up. Truck makes a little chattering-rattling when locks up....
I'm thinking to change rear diff fluid with 75W-140 and add motorcraft friction modifier xl-3....
Don't know if this will help, but it's a step I must do since I recently bought the truck.

A friend told me he had a similar issue on a Tahoe with rear posi, and changing the fluid with the correct one fixed it....hope this time work the same!

Yes, my Monty has a rear posi, the id tab says "3 L 73"

A "posi" may jerk and chatter, but I cannot see one "locking up". This could occur with the type of "posi" unit which uses "dogs" or teeth to bring about mechanical drive to both wheels. To my knowledge, all factory supplied "posi" designs use clutches designed to "slip" under high torque differences appearing between the two axles, 100 to 200 ft. lbs., let's say.

I would lean more toward broken or damaged differential gears in your case. However, do try friction modifier and fresh lubricant first. Tearing apart the center section is not for the "weak at heart"! imp