Transfer case pump rub sound?

[LeakySeals]

I have what sounds like a chain dragging while climbing hills and turning right. Its hard to pinpoint because I have to drive it to replicate, but it seems to be coming from the area of the AWD transfer case. Is that the "pump rub" sound, where the pump comes in contact with that clip? Or could it really be a loose chain?

 

[cpayne5]

Your Escalade has a BW4481 transfer case, not one of the NP units that are susceptible to pump rub.

 

[LeakySeals]

Originally Posted By: cpayne5
Your Escalade has a BW4481 transfer case, not one of the NP units that are susceptible to pump rub.

Thanks! I just finished watching BW4481 teardowns on YouTube. It looks basic compared to the other GM cases with pump rub. Do you think the chain is actually hitting the case under certain conditions? It had 135k of climbing hills before the fluid was changed. Black! I have changed it 4 times in the past 10k trying to figure out what it likes. Very picky

 

[cpayne5]

What fluid are you using? Most people will tell you to use AutoTrak II in all GM transfer cases, but this one, and a few others are specifically spec'd for Dex3 ATF. GM Part # 88861800

I'd be surprised if the transfer case is failing this early. At 140k, it should just now be broken in.

 

[LeakySeals]

Originally Posted By: cpayne5
What fluid are you using? Most people will tell you to use AutoTrak II in all GM transfer cases, but this one, and a few others are specifically spec'd for Dex3 ATF. GM Part # 88861800

I'd be surprised if the transfer case is failing this early. At 140k, it should just now be broken in.

Right now, Mobil 1 syn ATF. Its been in for a couple of months.

 

[clinebarger]

If the chain is hitting the case, You would see magnesium shavings in the oil you've been draining out. Have you checked the front drive axles & wheel bearings?

 

[The_Eric]

Originally Posted By: clinebarger
If the chain is hitting the case, You would see magnesium shavings in the oil you've been draining out. Have you checked the front drive axles & wheel bearings?


In addition to this, check the rear brake backing plates.

 

[LeakySeals]

Originally Posted By: The_Eric
Originally Posted By: clinebarger
If the chain is hitting the case, You would see magnesium shavings in the oil you've been draining out. Have you checked the front drive axles & wheel bearings?


In addition to this, check the rear brake backing plates.

Hmmm.. I put new Raybestos rotors on a few months ago.. Will check that, thanks

 

[LeakySeals]

OK its not backing plates. Still convinced it sounds like a chain dragging at times.

Is the BW4481 AWD chain in use and under load full time?

I surfed this up - "TSB 11-04-21-004 FEB 11 Transfer Case - Drive Chain And Sprocket Revision"

There is no description out there on the interwebs, just behind paid websites. Could a translation be.. the chain stretched wearing out the sprockets, replace them?

I can't video this chain noise, but I can create a video of the drive train slop. Maybe its normal, but there's a couple of inches of play at the TC in Park. Would that be helpful?

 

[The_Eric]

The contents of the TSB:

Quote:

Production assemblies were built with the 1.25 inch parts. The new service assemblies built effective 12/20/10 (and the SN breakpoint below) are built using the 1.50 inch parts.

Service parts have revised the component usage and parts release strategy to make ONLY the 1.50 inch parts available. If replacement of a 1.25 inch drive sprocket, driven sprocket or chain is required, all must be replaced using the 1.50 inch components.


To determine the design level of the components within the assembly, measure the width of the drive sprocket teeth.

Borg Warner 4481/4482 transfer case service assemblies will include a revised design drive sprocket (25), driven sprocket (38) and drive chain (26). The new design drive sprockets and chain are 38.1 mm (1.50 in) width design. The earlier components were a 31.75 mm (1.25 in) width design. Service assemblies built after the 60DBC070376 (44-81 1 Speed, AWD) or 60CZC014106 (44-82 2 Speed, AWD) serial number breakpoint will include the 38.1 mm (1.50 in) design components. If replacement of the drive sprockets or chain is required on an earlier design assembly with 31.75 mm (1.25 in) components, the drive sprocket, driven sprocket and chain all must be replaced with the 38.1 mm (1.50 in) components. The 38.1 mm (1.50 in) design components will be the only design available for service.


To determine the design level of the components within the assembly, measure the width of the drive sprocket teeth.


There are also some illustrations too, but I think you get the idea.

 

[The_Eric]

Are all your tires the same brand, model and basic circumference? AWD t-cases don't like mis-matched tires. Even ones that are heavily worn vs lightly worn.

 

[LeakySeals]

Originally Posted By: The_Eric
The contents of the TSB:

Quote:

Production assemblies were built with the 1.25 inch parts. The new service assemblies built effective 12/20/10 (and the SN breakpoint below) are built using the 1.50 inch parts.

Service parts have revised the component usage and parts release strategy to make ONLY the 1.50 inch parts available. If replacement of a 1.25 inch drive sprocket, driven sprocket or chain is required, all must be replaced using the 1.50 inch components.


To determine the design level of the components within the assembly, measure the width of the drive sprocket teeth.

Borg Warner 4481/4482 transfer case service assemblies will include a revised design drive sprocket (25), driven sprocket (38) and drive chain (26). The new design drive sprockets and chain are 38.1 mm (1.50 in) width design. The earlier components were a 31.75 mm (1.25 in) width design. Service assemblies built after the 60DBC070376 (44-81 1 Speed, AWD) or 60CZC014106 (44-82 2 Speed, AWD) serial number breakpoint will include the 38.1 mm (1.50 in) design components. If replacement of the drive sprockets or chain is required on an earlier design assembly with 31.75 mm (1.25 in) components, the drive sprocket, driven sprocket and chain all must be replaced with the 38.1 mm (1.50 in) components. The 38.1 mm (1.50 in) design components will be the only design available for service.


To determine the design level of the components within the assembly, measure the width of the drive sprocket teeth.


There are also some illustrations too, but I think you get the idea.


Ugh.. Its not clear whether I can just pop open the case and swap the chain. I think sprockets are ok, no metal in any drains. With larger sprockets would the chain be larger? The sprockets double price of parts to $400. I can get a rebuilt for $750. Wondering if its worth it.