trans and transfer case

[Bmsn95]

over the weekend my truck started giving me problems once again. Went on a drive probably 120 miles round trip, on my way back home the truck started making noise something similar to a plastic undercarriage protector dragging on the ground, nothing loud but enough to notice hey wtf is going on. Next day drove it around to try and guess what it could be. when i noticed the noise the most was on a declaration and by this time its more of a whine. read something about pump rub so i started at the t-case and changed the fluid. After the t-case fluid change backed it out of the driveway put the truck in drive and it pops out of gear like a manual transmission would under a load and sometimes just at idle, as i gimped it back in the only gear it would get into which was 1st i noticed that the abs/ebrake light had shown up on the dash.

anyone have a similar problem? and whats my next option from here?

 

[Muff]

Have you checked the fluid in the trans with the truck at operating temp? Do you have a way to read the check engine codes?

 

[Bmsn95]

checked trans last night and fluid is good and i have a ppe tuner that reads codes but the last time i checked it had what seemed like a lot of codes but ill see what i have and post them

 

[Bmsn95]

I have a U1041 and U1024

 

[Muff]

Those are the only codes correct?

 

[schulte]

Pull the speed sensor out of the transfer case and see if you can wiggle the tone ring. Chances are you have pump rub and it has trashed a bearing in the xfer case.

It pops out of "Gear" because the mode fork is worn all the way down and isn't holding the slide collar in 2hi.

You'll need a new mode fork, probably range fork, maybe slide collars, some bearings, a case half if yours has a hole worn through, and maybe a new pump at minimum. It might be cheaper/easier to just get a new case.

 

[Bmsn95]

those were the only 2 codes to pop up.

schulte all the components you're talking about are dealing with the transfer case correct?

i did feel around for a hole didn't notice anything except for one that has a rubber grommet covering it on the top side of the rear output shaft housing.

 

[schulte]

those were the only 2 codes to pop up.

schulte all the components you're talking about are dealing with the transfer case correct?

i did feel around for a hole didn't notice anything except for one that has a rubber grommet covering it on the top side of the rear output shaft housing.

Yes everything I was mentioning is in the transfer case. If you feel around the top side of the rear half of the case, you should come across a wire (smaller, not the larger harness on the front half of the case that goes to the encoder motor), follow that wire to a 2 pin plug in a sensor (speed sensor).

That speed sensor can be removed (18 or 19mm socket, be careful, it's plastic) and the tone ring in question is there. If it feels loose, pull the rear driveshaft and see if you can move the output shaft of the transfer case up and down a lot.

If so, you have issues, and you need to pull the transfer case.

 

[schulte]

This is what can happen with pump rub.

1. The pump anti rattle clip breaks and the pump rubs a hole through the case over thousands of miles.

2. Fluid slowly leaks from said hole until the case is low/out of fluid.

3. The range and mode selection forks have plastic wear pads over the aluminum forks. Those pads are destroyed due to lack of lubrication. The aluminum forks begin to wear against the sliding collars which are made of steel.

4. The output bushing begins to wear excessively, along with other bearings and pretty much everything that should be lubricated.

5. You first notice it because the transfer case will no longer stay in gear because the mode fork is worn and it allows the collar to slide into neutral.

or...

6. You start getting erradic spedometer, codes, range shift inhibited, abs issues, because the worn bushing is allowing the shaft to move around and the tone ring is going into and out of range of the speed sensor, interrupting speed signal which is needed for speedo, shifting, abs, etc.

It is sometimes cheaper to just buy an entire new or reman xfer case depending on how much carnage has happened, but you or a good shop like Mike can also replace just the parts that are bad.

 

[Kodymccunelbz]

Ok just bought this truck a month or so ago and noticed it was leaking granny fluid. Didn't think much of it. Went to get my oil changed and truck services and they said my transfer case was low and the gasket between tranny and transfer case was bad. Wouldn't that fill the transfer case up? And I drained the fluid in transfer case and added new. There was no Metallics in it. Do I just replace the gasket? I'm new to Allison.

 

[Kodymccunelbz]

Also in the process of trying to figure out where it was leaking from. (Want to make sure I don't have a hole from pump rub.) I noticed that if you push up on transfer case it moves about an inch or two. I have problems just need to figure out what before I can tear into it

 

[schulte]

Also in the process of trying to figure out where it was leaking from. (Want to make sure I don't have a hole from pump rub.) I noticed that if you push up on transfer case it moves about an inch or two. I have problems just need to figure out what before I can tear into it

This doesn't sounds right at all.

 

[Bmsn95]

hey schulte, thanks for all your help. At this point i think ill just buy a new t-case do the pump rub kit while i have it on the work bench and call it a day.

 

[schulte]

hey schulte, thanks for all your help. At this point i think ill just buy a new t-case do the pump rub kit while i have it on the work bench and call it a day.

When you go to do the pump rub kit (or open any transfer case), a snap ring pliers of this style is a must.

You'll see why when you go to free the retaining ring from the shaft bearing in the rear half of the case (accessed through the oval shaped rubber port on the top of the rear case half.

 

[Bmsn95]

cool man, thank you. Have any ideas on where i should buy a transfer case? or just search the web?

 

[schulte]

cool man, thank you. Have any ideas on where i should buy a transfer case? or just search the web?

Check ebay, otherwise Rockauto.com or if you want OEM brand new maybe partszoneonline.com or gmpartsgiant.com.

I would just look around and compare prices.

 

[Kodymccunelbz]

This doesn't sounds right at all.

I know. My transfer case is losing fluid. But it's leaking from the gasket makes no sense

 

[Bmsn95]

Anyone know what would cause a low sounding whine in 1st and 2nd gear, happens on acceleration and deceleration. Noise disappears once the truck shifts in 3rd gear.

 

[Bmsn95]

If anyone was curious about the noise. Further investigation has located that noise to the p1 gear in the transmission. Didn't think I'd be doing a rebuild with 156k on the truck.