2003 4x4 noisy when turning or hard accel

Greetings all -

Son is home from college for the holidays so we get to work on his 2003 2 door Blazer with 3 button 4x4, 4.3 vortec, 112000 miles and never had 4x4 service i know of - just fluid level checks. This is one of 7 or 8 Blazer/Jimmys I have owned. Thanksgiving weekend I replaced vacuum switch (ball was stuck) on top of the xfer case since the front actuator was partly engage and he had a ticking noise from the front diff (we found this in the summer after doing some other maintenance and I pulled the pin out to the actuator so it would not pull the cable). Yesterday I replace the vacuum purge valve to address small/large vacuum leaks. That also fixed his slow change (defrost to vent to heat) on the HVAC control. Also replaced the thermostat to fix a P0128.

Anyway - on the drive to Advance to get the stat he created the noise he hears when in 4wd hi (never needs 4lo). We were stopped on hard pack snow and he made a right turn with moderate acceleration - Sounds likes a gear skip or bind then unbind noise - hard to describe. On the way home, on hard pack snow/ice going straight he accelerated hard and got the same noise.

Going slow in a turn or easy accel on straight in 4hi there is no noise. He has good tires, new last year. We pulled the battery, started the truck up and watched the front diff actuator work just fine, and we hear the xfer case encoder engaging/dis-engaging. No codes or ses lights. It is going into the dealer on Monday for a $100 diagnostic.

Any idea what to expect? Or what to check before GM gets more of my money?

Thanks in advance - dkjen

If it is just a crow hop on turning.
That is normal for 4W drive.
Do not use 4W on dry payment.
Are all tires matched up?

Check all axel and drive shaft U joints and double shaft joints.

112000 miles of no 4X4 servicing means get ready for some serious repairs/rebuilding of the 4X4 system. The time is now to get it serviced and hope for the best.

could be cv joints need replacing.

+1 on the cv joints.

Greetings again –

I have the Blazer back from the dealer, $928 later. Based on what the service rep says (I love it when I know more about the area then the rep does) the parts used and returned it seems there was a problem with front diff engagement cable. She thought it was broken but maybe it was hung or stretched. Anyway, they replaced it along with the sliding gear the cable moves, via a shift fork, and the gear that appears to engage the diff. There were a couple of bearings and seals as well. I also had the full 4x4 service package done which seems way to costly at $300 for oil changes of the diffs and transfer case, even with synthetic oils.

Son has it back at college on the west side of Michigan so it will get a work out the next few months. Hope this helps others in the future.

dkjen

Thanks for posting back how it went.
Dealer service reps are usually only just ticket writers.
The techs/mechanics are the one that does the work and have to figure out the problem.
Also
To save money.

You might consider finding a good indepent repair shop for repair.


Check around Ask around
Word of mouth.
Family friends coworkers neighbors business people and delivery people.
Mailmen and parcel delivery people get around and notice a lot of stuff.
Even a good parts house knows what shops are good and not good.
Chamber of commerce and better business bureau and city hall.
If you find a good referral to a repair shop go look them over and talk to them.
Look for a clean looking busy place with nice people running it.
Ask a few questions and ask about their qualifications and training.
Not all places have trained tech/mechanics.
If they do not find a place that does.
Even all dealers do not have all trained techs/mechanics.

I have a local shop I trust (so far) for repairs I don't want to do. I do trust the local dealer (so far) they just cost more. The write up lady was trying to impress me with her 4x4 knowledge but i wasn't buying. Unfortunetly, son was home between holidays and we didn't have time for the local shop. He's on his first 160 mile round trip to his internship job today so I will hear tonight how the Blazer ran. With the lake effect snow i am sure he will need the 4wd.