Check that Duramax Transfer Case!

Status
Not open for further replies.
My apologies deet - I was predisposed to thinking of GM because of the topic and your mention of grape juice. I got caught in a mindset and didn't follow you.
 
Originally Posted By: dnewton3
My apologies deet - I was predisposed to thinking of GM because of the topic and your mention of grape juice. I got caught in a mindset and didn't follow you.




I figured the fluid might have been installed at NP, the case shipped from the point of manufacture full of fluid. The reason I asked my GM-guy was that both GM and Dodge use the NP transfercase...figure it might have been a commonality.

Again, it didn't resemble any fluid Dodge uses...another reason I figured it was a source-filled piece.
 
Since reading this, I've looked on the internet and there are a number of half ton trucks with the same issue. I've got a 2005 GMC Sierra with the manually shifted transfer case. How do I find out if I have one of the transfer cases with this defect? When I bought the truck, I drained what looked like the factory fill at 67k & did a couple of short fills to flush out any iron and eventually filled it with Amsoil. I'll keep an eye on the fluid level, but I'm concerned now that I might have this issue down the road.
 
When you say the "same issue" are you referring to the claimed evaporation, or pump rub?

Keeping an eye on the lube level solves that fluid level problem directly; it is the correct approach to proper maintenance.

Pump rub can only be confirmed via removal and dissassembly of the t-case. I supposed one might be able to distinguish it in a PC analysis. I doubt that a UOA would pick it up, because the resultant particles that come from the pump rub are likely to be larger than 5um, and that is the upper limit of spectral analysis; hence a UOA may very well not see the increase in wear elements. The real problem is that so very few people do UOA analysis on xfer case fluids, that there is probably no basis for "average" numbers for comparison. Typically the capacity of an xfer case is so small that it's way chepaer to OCI then to UOA. So, you come full circle to the "Do I have pump rub?" question; the only way to know FOR SURE is to take it apart and look. And if you're going to go to that extreme, then you might as well install the pre-emptive fix while you're in there.
 
Originally Posted By: dnewton3
When you say the "same issue" are you referring to the claimed evaporation, or pump rub?

Keeping an eye on the lube level solves that fluid level problem directly; it is the correct approach to proper maintenance.

Pump rub can only be confirmed via removal and dissassembly of the t-case. I supposed one might be able to distinguish it in a PC analysis. I doubt that a UOA would pick it up, because the resultant particles that come from the pump rub are likely to be larger than 5um, and that is the upper limit of spectral analysis; hence a UOA may very well not see the increase in wear elements. The real problem is that so very few people do UOA analysis on xfer case fluids, that there is probably no basis for "average" numbers for comparison. Typically the capacity of an xfer case is so small that it's way chepaer to OCI then to UOA. So, you come full circle to the "Do I have pump rub?" question; the only way to know FOR SURE is to take it apart and look. And if you're going to go to that extreme, then you might as well install the pre-emptive fix while you're in there.


I apologize - sometimes when typing it all makes sense to me but not the reader! I was wondering if the pump rub issue was only happening on certain transfer cases. And how can I find out if my model is one of those with that issue? Is there a TSB that states which units are affected?

Thanks!
 
Originally Posted By: dnewton3
When you say the "same issue" are you referring to the claimed evaporation, or pump rub?

Keeping an eye on the lube level solves that fluid level problem directly; it is the correct approach to proper maintenance.

Pump rub can only be confirmed via removal and dissassembly of the t-case. I supposed one might be able to distinguish it in a PC analysis. I doubt that a UOA would pick it up, because the resultant particles that come from the pump rub are likely to be larger than 5um, and that is the upper limit of spectral analysis; hence a UOA may very well not see the increase in wear elements. The real problem is that so very few people do UOA analysis on xfer case fluids, that there is probably no basis for "average" numbers for comparison. Typically the capacity of an xfer case is so small that it's way chepaer to OCI then to UOA. So, you come full circle to the "Do I have pump rub?" question; the only way to know FOR SURE is to take it apart and look. And if you're going to go to that extreme, then you might as well install the pre-emptive fix while you're in there.


Did you have any signs up pump rub when you took your transfer case apart and installed the protective shield?
 
Status
Not open for further replies.
Back
Top