Screwed up my 4 wheel drive?

[Dennis22]

Lets start by saying I had a brain fart.
Took off on a trip, about 100 miles and driving an average of 70 mph I pulled into a rest area and had a hard time turning into a parking spot, I looked over and I had it in 4 wheel drive the whole trip. Took it out of 4x4 (electronic) and continued on. Now, when I put it in 4x4 it has a slight vibration when you drive down the road,the 4x4 works but has the vibration. Any Ideas?
96 suburban
6.5 TD

[EscaladeDiesel]

Wheel bearings maybe? Years ago when I have my 1995 K2500 TD I drove it in 4wd for 600 miles at freeway speeds not knowing it wasnt all-the-time 4x4, and it was ok.

[Beedee]

Might be a good idea to check the boots on your CV joints, if they are cracked the high speed might have thrown all of the grease out. Check for any tattletale signs of grease from the joints.

[C.K. Piquup]

Probably CVs,either axle or drive shaft.I`ve done it.Had to use 4wd to back in,sat all weekend,took off Monday.It wasn`t that far or fast,though,so I didn`t have a problem.I`m sure we`re not the only ones.I kick it out everytime,now,before I get out of the truck.(been driving 4wd all my driving years)DOUGH!!!

[rjschoolcraft]

A more likely scenario...

The oil is low in the front differential. It probably was a little low to start with, but the high speed run in 4wd on pavement puts a lot of heat into the oil making it expand. It probably pushed a lot of oil out the vent and is now really low.

My suggestion...

Drain the oil in the diff. Fill with clean, fresh oil and see if this helps.

The CV joints turn all the time regardless of whether the front end is engaged or not.

[markrinker]

My 1994 3500 flatbeds ran in 4WD (high) almost constantly this winter from November to present. Occasionally on dry pavement, I'll notice it 'tug' around a corner, and bump it back into 2WD, but within the hour its back in 4WD for snow plowing, towing, etc.

If dry pavement and 4-high is harmful, I haven't seen it. All trucks get all fluids annually...

MRE

[Kennedy]

Likely just a little driveshaft vibration. Check the fluids, and Ujoints and if things seem ok, don't sweat it...

[Dennis22]

Changed the fluid out in the front differential, it was low, the vibration did go away slightly,it does seem louder when I put it in 4x4 than it used to be.
Thanks for your help!
Dennis

[DaveW]

Just out of curiousity what is the fluid capacity of the front diff on a K2500???

[CareyWeber]

Dennis,

Mostly likely you have some slop in the front drive shaft slip yoke.

The turn all the time on our trucks and the yoke wear over time.

Grab the yoke where the splines enter the yoke and push it up and down if it moves you likely found your vibration.

At some time it will get bad enough to require replacement. They do where out and require replacement you might get another 1 to 3 years out of it.

Carey

[Dennis22]

Carey and all,
I only get the vibration,(wich is not as bad as before I changed out the oil) and the increased sound when it is in 4x4. could I have damaged the gears in the differential, if I did, what would the "damage" act like?

[rjschoolcraft]

The drive shaft does not turn "all the time". It only turns when the 4wd is engaged.

The most likely gear damage to result from lack of oil is scoring of the tooth surfaces. This will degrade the profile and mesh characteristics causing an audible increase in noise. The scoring will lead to pitting (compressive fatigue failure of the tooth surface) with still more audible noise and vibration.

Lack of oil can cause spalling of the bearings as well...which will also cause an audible noise.

Either of these conditions will generate metal particles that should collect in the bottom of the differential. Most of these have either a magnetic pad or a magnetic drain plug to catch debris. After a few hundred miles of use, drain the oil and inspect for debris. If you have an unusually high amount of magnetic debris, you have a problem that will need to be addressed.

Could it be that you are just keenly aware of things since you had this incident? Maybe the noise was always there?

[Dennis22]

Ron,
you may be right, I can't remember if it was this loud before when I put it into 4x4, I may be just more in tuned to the sounds when I put it in 4x4.I will check for more filings next time I change out the differential oil. Again, thanks for all the help.
Dennis

[kowsoc]

I had a vibration or noise in mine this winter...only in 4 wheel drive also. Turned out to be a tight u-joint on the front drive shaft. I replaced it for $16 and all is well. I discovered it when I was under the truck changing oil. The shaft should spin freely by hand. Mine had a tight spot. Running yours in 4x4 on pavement would have put a lot of strain on the front driveline......the weakest link....hopefully one or both of the u-joints. The shaft is real easy to take off and inspect.

[C.K. Piquup]

If the vibration occurs in 4wd only,check those driveshaft components(U-joints/yoke splines).If either or both were low on lube,it could have caused rapid wear or just ate up what little lube there was.If you`re lucky,lubing may be all it takes to smooth it out.

[C.K. Piquup]

What noise are you hearing,clunk,rumble,clacking,or a whine?I know that sounds funny,but try to describe what you hear.

[Dennis22]

it is definently a whine, no clunking or banging. it is a loud consistant noise
Dennis

[patrick m.]

my front diff actuator was stuck with the front diff engaged and i didnt know it. so the front diff was turning all of the time eventhough the transfer case was not in 4wd.
the diff pushed all of the fluid out of a leaking yoke seal over a period of time, and finally locked up, spinning the pinion yoke in the case, ruining the case (big case, 9.5 inch ring gear) OUCH!
after updating the actuator, and many hundreds of dollars later, i check all fluids often.

I used to peek at the housings and their surroundings, if they were clean, must mean no leaks.......not so!

my point is, you can have the front diff engaged, and the transfer case not. the transfer case is the point of dissconnect in this situation so you dont feel the front end "binding" in a sharp turn. could be source of slight vibration, add a leaky seal, problems are headed your way.