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1992 s10 blazer


Sent to Car Experts September 14, 2006 5:05 p.m.

My S10blazer is the 4.3 vortec 4 wheel dr..latly I've been having problems with it seeming to want to try and ingage into 4 wheel dr while i am drivig it has a humming sound when i slow down u will here it glunk and then be fine... use to do it once in a great while,,,but now it is everyday mostly when i am going at higher speeds 35 and up...if i hit the switch for 4wheel high u can here it engage and be fine...till the next time...the 4 wheel works just fine...and now i can't get to go into 4wheel hi at all...and the problem is still there...i'm pretty sure i should take it some where for this problem...but whould like to have some idea whats going on...

Optional Information:
1992 Chevrolet s10blazer 4.3vortec

Already Tried:
nothing..not sure what to do
Customer (name blocked for privacy)
Status: Closed   Value: $15   
Answer
September 14, 2006 5:28 p.m. (22 minutes and 58 seconds later)
REPLIED Check Mark

Some vehicles may exhibit a clunk noise that can be heard on a 2-3 upshift or a 3-2 downshift.

During a 2-3 upshift, the 2-4 band is released and the 3-4 clutch is applied. The timing of this shift can cause a momentary torque reversal of the output shaft that results in a clunk noise. This same torque reversal can also occur on a 3-2 downshift when the 3-4 clutch is released and the 2-4 band applied. This condition may be worse on a 4-wheel drive vehicle due to the additional tolerances in the transfer case.

This is a normal condition. No repairs should be attempted.

Some owners of light duty trucks equipped with automatic transmissions may comment that the vehicle exhibits a clunk noise when shifting between Park and Drive, Park and Reverse, or Drive and Reverse. Similarly, owners of vehicles equipped with automatic or manual transmissions may comment that the vehicle exhibits a clunk noise while driving when the accelerator is quickly depressed and then released.

Whenever there are two or more gears interacting with one another, there must be a certain amount of clearance between those gears in order for the gears to operate properly. This clearance or freeplay (also known as lash) can translate into a clunk noise whenever the gear is loaded and unloaded quickly, or whenever the direction of rotation is reversed. The more gears you have in a system, the more freeplay the total system will have.

The clunk noise that owners sometimes hear may be the result of a buildup of freeplay (lash) between the components in the driveline.

For example, the potential for a driveline clunk would be greater in a 4-wheel drive or all-wheel drive vehicle than a 2-wheel drive vehicle. This is because in addition to the freeplay from the rear axle gears, the universal joints, and the transmission (common to both vehicles), the 4-wheel drive transfer case gears (and their associated clearances) add additional freeplay to the driveline.

In service, dealers are discouraged from attempting to repair driveline clunk conditions for the following reasons:

  • Comments of driveline clunk are almost never the result of one individual component with excessive lash, but rather the result of the added affect of freeplay (or lash) present in all of the driveline components.

    Because all of the components in the driveline have a certain amount of lash by design, changing driveline components may not result in a satisfactory lash reduction.

  • While some owners may find the clunk noise objectionable, this will not adversely affect durability or performance.

THIS WILL EXPLAIN SOME OF YOUR PROBLEM,HOWEVER THE WHINE IS NOT INCLUDED IN THE DIAGNOSES.THIS SOUNDS LIKE THE TRANSFER CASE IS LOW ON FLUID.ALSO THE ENGAGEMENT IS PROBABLY THE SELECTER MIS ADJUSTED OR A ELETRICAL PROBLEM.

TRANSFER CASE NOISY IN ALL MODES
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ASE MASTER TECH 40 YEARS IN THE INDUSTRY
Reply to GENE
Sent September 14, 2006 6:00 p.m. (32 minutes and 17 seconds later)

no this not normal the clunk come after the noise that sounds like it is trying to engage all my fluids are fine the clunk come when coming to a almost stop and then it is all fine till the next time it happens....and i can make the sound go away when i put it in 4wheel hi
Customer (name blocked for privacy)
Answer
September 14, 2006 6:06 p.m. (6 minutes and 6 seconds later)
REPLIED Check Mark

Does this happen every time and do you have any vibration at any speed?

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If i have been helpful,please click accept.
If you need further assistance just ask and i'll be glad to help
PictureGENE  -- Auto Service Technician -- 100% Positive Feedback on 509 Car Accepts
ASE MASTER TECH 40 YEARS IN THE INDUSTRY
Reply to GENE
Sent September 15, 2006 4:06 p.m. (21 hours and 59 minutes later)

no this dose not happen every time..but it is happening more often...and there is no vibration and it most happens at a higher speed which u don't no till u start to slow down thats when u here it the most ..if on the highway i won't know till i am getting off the highway....and when i get down to 5 to 10 mph is when it clunks back to normal..
Customer (name blocked for privacy)
Answer
September 18, 2006 7:28 a.m. (2 days and 15 hours later)

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PictureGENE  -- Auto Service Technician -- 100% Positive Feedback on 509 Car Accepts
ASE MASTER TECH 40 YEARS IN THE INDUSTRY

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