Previous Np246 Pump Rub Repair? Pics...also, 4wd Doesn't Work&#33

[RumorsOFsurF]

Hello. I'm new here, and I'm having a problem with my recently bought 2003 Yukon.

 

I went up to the local mountains to do some shooting and exploring yesterday and I found out the 4WD doesn't work on my Yukon. It seemed to work off and on, which I thought was strange. When I got home I jacked the rear tires off the ground and tried all the 4wd modes, but the front tires weren't pulling in any mode. The front driveline wasn't turning, either, which rules out the front diff disconnect.

 

I've since researched the NP246 case and I also took it in to the local GMC dealership to have it checked out.

 

The tech at the dealership hooked up the diagnostic computer and tested everything, and the encoder and front actuator seemed to be working properly. He put it on the lift and all four tires were spinning. He then told me it seemed to be fine and sent me on my way. He told me if I could duplicate the condition to bring it back. I asked him if he tried the jack thing, but he didn't answer that question. I promptly took the vehicle to my Dad's auto body shop and lifted the rear off the ground and....the front STILL wasn't pulling. I figured at this point it was the clutches. When I returned he tried the diagnostic computer again and told me it was probably the clutches. If that's the case he said it would be 5.7 hours of labor just for R&I, plus parts. I have a warranty on the vehicle, so that SHOULD cover it, but they said if it didn't I would be responsible for the labor. That's an obvious one, but the adjuster had better not deny the claim. It's an internal drivetrain component, which is specifically mentioned in the warranty.

 

When I got home I looked at the case closely, and it appears as though the housing has been patched in a couple places that seem consistent with the "pump rub" problem that is common to these. Could this cause the clutches to wear out? Should I mention this to the shop? If it's been repaired and the rear case half is compromised I obviously want that replaced when they fix it.

 

 

Does this look like it's been patched? Sure does to me! Looks like it's at least two places. Note the bottom of the pic as well as the top.

 

[jro909]

i'm having a hard time deciding if thats a weld or road grime, if it is a weld then i don't think it would effect the internal gears unless the previous owner drove with the bleeding transfer case to the point that the front diff fried from lack of fluid or somethen

[RumorsOFsurF]

It's definitely not grime. I couldn't budge it with a screwdriver. I just kind of scraped at the edge of it a little. Hard as a rock.

[jro909]

if it was patched, thats a shotty weld bead...i would just get the whole thing replaced to be safe

[RumorsOFsurF]

It's a magnesium case. You can't weld it. It's likely JB weld.

[jro909]

i've heard of the magnesium case rub problem on the 900s but not on 800s, sorry i diden't realise that np246 was the mag case....jb weld sounds like a shady repair, i've built an entire gas tank out of the stuff but i can't imagine a legit dealer would use it for repair like that...

[RumorsOFsurF]

Anyone else have any idea whether this could have caused my failure?

[thearborbarber]

I would say it could especially if the transfer case went dry with the fluid leaking out. When my 2004 wore a hole in the case there was only about half a quart left in it.