Transfer case whinning

[Jostin]

1999 Suburban 1500, 5.7L 4x4- Auto- 160,001 miles exactly.

Felt and heard a slight thump, then heard what sounded like a twig snap. Another thump and a snap with a little crunch sound to it.

Vehicle moves fine during this entire time, was starting to pull forward from a dead stop after getting off an interstate. I was pulling about 1k in the trailer behind and on flat pavement. Was in 2HI.

Here's the problem. Immediatly after these noises. I got an intermitten high pitched whinning noise which very rapidly became a full time whine. Pulled over and looked under rig for leak. None. Was in park, gave it some juice and engine sounded fine... Climbed under and looked at my three week old new u-joint which appeared fine. Hopped back in and started to pull forward in which this air raid like whinning noise picked up immediatly upon movement. Head out the door and under the car at a slow movement allowed me to isolate noise to the transfer case. Back under and check drain plug... decent fluid color with no charred smells or noticable flakes of metal. Drove car my last 1/2 mile at speeds between about 5-20 mph. Whinning greater at 8-12mph then very suttle and intermitten at speeds of 12-20mph but hearing a snap, then grining noise... dissappears and is replace immediatly at lower speeds by whinning noise...

Just replaced rear diff in Dec. and services front diff and replaced the seal three weeks ago. New u-joints front and back... I'm 99% positive the sound is from the transfer case...

Any tips or pointers... experianced this before? Have three days to figure this out... Please help this decently experianced do-it-yourselfer.

Pump? Electric Actuator? Shift sensor/fork? I'M LOST!
My money is on the motor as the sinning siren sound is like that of a spent electric motor... however the car dose this in 2HI AND 4HI...

 

[Molson02536]

1999 Suburban 1500, 5.7L 4x4- Auto- 160,001 miles exactly.

Felt and heard a slight thump, then heard what sounded like a twig snap. Another thump and a snap with a little crunch sound to it.

Vehicle moves fine during this entire time, was starting to pull forward from a dead stop after getting off an interstate. I was pulling about 1k in the trailer behind and on flat pavement. Was in 2HI.

Here's the problem. Immediatly after these noises. I got an intermitten high pitched whinning noise which very rapidly became a full time whine. Pulled over and looked under rig for leak. None. Was in park, gave it some juice and engine sounded fine... Climbed under and looked at my three week old new u-joint which appeared fine. Hopped back in and started to pull forward in which this air raid like whinning noise picked up immediatly upon movement. Head out the door and under the car at a slow movement allowed me to isolate noise to the transfer case. Back under and check drain plug... decent fluid color with no charred smells or noticable flakes of metal. Drove car my last 1/2 mile at speeds between about 5-20 mph. Whinning greater at 8-12mph then very suttle and intermitten at speeds of 12-20mph but hearing a snap, then grining noise... dissappears and is replace immediatly at lower speeds by whinning noise...

Just replaced rear diff in Dec. and services front diff and replaced the seal three weeks ago. New u-joints front and back... I'm 99% positive the sound is from the transfer case...

Any tips or pointers... experianced this before? Have three days to figure this out... Please help this decently experianced do-it-yourselfer.

Pump? Electric Actuator? Shift sensor/fork? I'M LOST!
My money is on the motor as the sinning siren sound is like that of a spent electric motor... however the car dose this in 2HI AND 4HI...

This is a guess since i am not there, the factory snap ring on the output shaft that is prone to failure. This common failure generally is not noticeable at first allowing the main shaft to move back and forth eventually causing major damage and expensive repairs to the transfer case. With a broken rear shaft snap ring the main shaft is allowed to move and the oil pump can malfunctions causing improper or no lubrication.

Recommended replacement fluid is ATF. If you have a late model transfer case we suggest you purchase our Red Line Synthetic ATF at the same time as you service your transfer case.

1. Remove the driveshaft and the rear tail cone.

2. Remove the existing snap ring, replace the rear housing seal and its a good idea to inspect the tail shaft bushing for excessive wear.

3. Clean all surface areas and new snap ring on the shaft and reinstall in revers.

Good luck and keep me posted.

 

[Jostin]

Update

I had a few to mess with the car yesterday. I have lost the ability to leave the car in park. When shifted into park, the car acts as if it is neutral. Shifting into reverse was stiff at first. I tried to move the car back and the engine sounded great but the car had no movement. Immediatly following was a grinding sound that sounded like a can of screws being shaken. Now when I shift into reverse, this sound appears immediatly. Lost reverse. Shift into neutral from reverse and it took a few seconds going from neutral for the sound to disappear from the reverse rattle. Pushed car back, just fine. Placed into drive... No hesitation, smooth upon acceleration. whinning noise started up again, as described above. Not enough room in driveway to get car above 3-4 mph. None the less- appears smooth in drive upon acceleration (minus the noise)...

99 GMC K1500 Suburban, 5.7L 4x4, 4L60E auto trans., Electronic shift on dash with Auto 4HI. New Process 246 transfer case...

Climbed under car and had wife place in reverse to help locate exact placement of noise. Noise while in Reverse is where the transfer case meets with the transmission.

My gut tells me I need a new tranny... Not well experianced in this area to know if it is the transe case or tranny. Trying to also understand why.

Found junk yard deals.... Transfer case $550 (due to having auto 4HI)
Tranny $550 also...

Nearly broke and about broken... Need to figure this out... Please help!
Just going to pick up either or and do a total swap unless someone tells me it's not as bad as I fear....

Going to lower Tranny pan later today and inspect the fluid I just put in it about 350 miles ago... Will share more later. Thanks for reading.

 

[Molson02536]

I had a few to mess with the car yesterday. I have lost the ability to leave the car in park. When shifted into park, the car acts as if it is neutral. Shifting into reverse was stiff at first. I tried to move the car back and the engine sounded great but the car had no movement. Immediatly following was a grinding sound that sounded like a can of screws being shaken. Now when I shift into reverse, this sound appears immediatly. Lost reverse. Shift into neutral from reverse and it took a few seconds going from neutral for the sound to disappear from the reverse rattle. Pushed car back, just fine. Placed into drive... No hesitation, smooth upon acceleration. whinning noise started up again, as described above. Not enough room in driveway to get car above 3-4 mph. None the less- appears smooth in drive upon acceleration (minus the noise)...

99 GMC K1500 Suburban, 5.7L 4x4, 4L60E auto trans., Electronic shift on dash with Auto 4HI. New Process 246 transfer case...

Climbed under car and had wife place in reverse to help locate exact placement of noise. Noise while in Reverse is where the transfer case meets with the transmission.

My gut tells me I need a new tranny... Not well experianced in this area to know if it is the transe case or tranny. Trying to also understand why.

Found junk yard deals.... Transfer case $550 (due to having auto 4HI)
Tranny $550 also...

Nearly broke and about broken... Need to figure this out... Please help!
Just going to pick up either or and do a total swap unless someone tells me it's not as bad as I fear....

Going to lower Tranny pan later today and inspect the fluid I just put in it about 350 miles ago... Will share more later. Thanks for reading.

1. low, slipping or no reverse: “lo-reverse” clutches are worn out, fluid leak in the reverse apply circuit, or broken sunshell.

2. Sudden grinding noise with no prior warning primarily in 2nd gear, behavior in reverse may be abnormal; sunshell is fractured. R&R. Try not to run or drive the car or further damage could result.

3. 1st and 3rd only, no 2,4 or R; sunshell is fractured or splines are sheared off. R&R. Try not to run or drive the car or further damage could result.

4. Trans seems noisy when moving in 1st and Reverse, noise goes away instantly if you shift to N or the trans goes into 3rd gear: Reaction planetary is worn out due to high miles or insufficient lubrication. Not a critical failure, but not a good sign either.

5. Needle bearings in the pan, first gear and/or reverse may be noisy: Either a torrington bearing or a planetary bearing is on its way out. Trans will eventually die a loud, catastrophic death. Cheaper to rebuild now (saves further damage to hard parts), but requires R&R. It is drivable until it breaks.

These are just a few things that could be wrong with your transmission that you have described. Put a line pressure gauge (or visit a local trans shop) on the pressure test port and go for a drive to verify proper line pressure. Base pressure at idle in P,N,OD should be around 70psi and around 140psi in R. Max line pressure should be at least 190psi at WOT in 1st or 2nd, 225psi is optimum. If base pressure is low, trans or pump is worn out. If max pressure is low, check EPC solenoid. If reverse is slow to engage, and line pressure does not come up to at least 130psi in reverse, replace the boost valve with a Transgo 0.490' or 0.500" boost valve (easy fix in pan).

Keep me posted.

 

[Jostin]

Molson...

Thanks a bunch. A little confused perhapse but I have all day to learn...
Problems match somewhat to # 1,3, and 4... Especially the last few.

In-laws have kept me ragged enough to not have dropped the pan yet... I LOVE THIS WEEKS SUPRISES!

No Park, no Reverse and very noisy, Neutral appears "safe", Drive in first and second whine when accelerator pedal is pressed and it gets louder as I accelerate and becomes a clunking/grinding noise as I hit third, yet still rides smooth and shifts somewhat normal.

I guess for clarification with my last two posts being considered. As in my very amatured yet detailed descriptions I have posted. I need to keep my eyes pasted more towards the tranny than the transfer case itself at this time?