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Darn 4wd issues, what the heck!?

Michael Condon

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Michael Condon Enthusiast

Michael Condon

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Hey Guys! I bought an 01 sierra 2500hd, 6.0 198xxx.

I use it as my daily driver. (:/)

Anyways, when in 4 wheel drive, i am hearing and feeling a clunking sound not entiringly unlike that of the cv axels. the sound occurs going straight forward and straight in reverse. higher engine rpm, the faster the clunking. (almost as if a belt was turning faster than a pully.) This sound occurred with and without a goose neck trailer attached.

i replaced the cv axels and the problem, noises and feelings continue. well i thought the Transfer case would be the next logical place to look,  and since i was doing a tranny flush thought i would take out the Tcase and look inside  as well as do a pump rub fix. the inside looks flawless besides the pump  clip being broken.

I am lost gents. I do not know where to go next. im going to order a the merchant pump rub fix but besides that i dont know where to turn. could the front differential be the problem maker? 

Formulabruce Enthusiast

Formulabruce

Posted
Posted

Could be this truck needs the steering column update done... Just tossing that out there

davester Senior Enthusiast

davester

Posted
Posted
1 hour ago, Michael Condon said:

Would they really make that noise? What should they feel like?

Yes, they can.  Grab the shaft at each end and see if you can move it at all in both directions relative to the u-joint.  and see if you can rotate one end of each ujoint a bit relative to the other side of it.

 

The CV joints on the front axles should make noise all the time, as they rotate all the time, being permanently connected to the wheels.

 

Another test you could try would be to unplug the actuator in the front axle (do this when the truck is in 2wd), then drive around a bit in 4wd and see if you hear the same sound.  What this does is cause the front driveshaft to spin, but it doesn't transmit the power to the front wheels.  If you only hear the sound in 4wd doing this, then it really points to the u-joints.  If it doesn't, then it points more towards the cv's.

Michael Condon Enthusiast

Michael Condon

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so i had a mechanic buddy come over and double check the drive shaft and Tcase. Tcase is in great shape. and drive shaft is fine, however, drive shaft is aftermarket, and buddy thinks that a problem could be from a front or rear dif replacement using the wrong gears. Im going to check the gearing difference sometime this week. hopefully thats not it :(

davester Senior Enthusiast

davester

Posted
Posted

Um, no.  If the front and rear diffs are geared differently (ie, 3.73 up front, 4.10 in the rear), you will notice IMMEDIATELY that you've got a serious problem.  Driving on any pavement you will get crazy tire scrubbing going in a straight line, and the truck will be virtually undriveable.  You'll also need a lot more power just to get the truck to move.

silveradosid Senior Enthusiast

silveradosid

Posted
Posted

how much play is there in the rear diff friends 2005 hd had this problem and it turned out that there was so much play in the rear that when it was in 4x4 the front was pulling and the rear was knocking

johnandchrisinmo Enthusiast

johnandchrisinmo

Posted
Posted

This only occurs in 4 wheel drive?  Are the front and back tires the same size with similar tread wear? If not the difference in the circumferance might be enough to cause some tire scrub even in straight line.  

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