4wd vibration and squeeling

Hypnotoad

Original poster
Member
Dec 5, 2011
1,584
Strange thing happened the other day. My wife was driving our Trailblazer and she calls me and tells that the car is vibrating and making a strange squeeling noise. So I have her pull over ASAP.

Later, I get to it and test drive it and find that it is vibrating in 4wd only, and not in 2wd and AWD. Also, the squeeling went away.

I get it home and shut it off. I come back to it later, and everything is working normal again, like nothing was ever happened. No vibrations, no sounds and 4wd is engaging as it should.

Are there any good explainations why this would happen?
 

Denali n DOO

Member
May 22, 2012
5,596
Hypnotoad said:
Strange thing happened the other day. My wife was driving our Trailblazer and she calls me and tells that the car is vibrating and making a strange squeeling noise. So I have her pull over ASAP.

Later, I get to it and test drive it and find that it is vibrating in 4wd only, and not in 2wd and AWD. Also, the squeeling went away.

I get it home and shut it off. I come back to it later, and everything is working normal again, like nothing was ever happened. No vibrations, no sounds and 4wd is engaging as it should.

Are there any good explainations why this would happen?

Maybe the disconnect didn't engage properly/fully that one time, for reasons I wouldn't know. I would think Roadie might know tho?
 

The_Roadie

Lifetime VIP Donor
Member
Nov 19, 2011
9,957
Portland, OR
Could be the disconnect engaged while the vibration happened, and is now FAILING to engage.

Or she was making turns on dry pavement and it was driveline bind-up. What were the pavement conditions, and why was she in 4HI anyway?

If you engage 4HI now can you get bind-up when you expect to? How many miles, and is your 50K transfer case fluid change current? Diffs checked or changed at 100K?
 

Hypnotoad

Original poster
Member
Dec 5, 2011
1,584
the roadie said:
Could be the disconnect engaged while the vibration happened, and is now FAILING to engage.

Or she was making turns on dry pavement and it was driveline bind-up. What were the pavement conditions, and why was she in 4HI anyway?

If you engage 4HI now can you get bind-up when you expect to? How many miles, and is your 50K transfer case fluid change current? Diffs checked or changed at 100K?

I'm just going by what she said. She was going straight while it was shakin and squeeling. We just got hit by a lot of snow and the roads are terrible. The truck was already engaged in 4wd previously and working (at least that what she thinks), then this started happening.

4hi works as it's supposed to, in fact everything does now. The car has 100k miles and the diffs, transfer case, and transmission were all changed at 75k miles. I admit, I haven't check the fluids yet.
 

The_Roadie

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Member
Nov 19, 2011
9,957
Portland, OR
Could she tell if the frequency of shaking was proportional to road speed (a definite driveline issue) or engine RPM (problem with a rotating part on the engine)? I might have thought lump of ice caught somewhere except all the external rotating parts like CV shafts rotate the same in 2HI and 4HI, so there's no difference there.
 

Hypnotoad

Original poster
Member
Dec 5, 2011
1,584
the roadie said:
I might have thought lump of ice caught somewhere except all the external rotating parts like CV shafts rotate the same in 2HI and 4HI, so there's no difference there.

This is what I thought, but couldn't figure what it could have stuck to either.

I have a theory that the squeeling may have been tires spinning on ice, but that wouldn't explain the severe vibration. Maybe it could have been an ABS malfunction for all I know. My wife is extremely clueless about cars.

I'm gonna check fluid levels and go from there. It seems there isn't much else I can do since the Trailblazer is working as it's supposed to.

Thanks for the help.
 

Hypnotoad

Original poster
Member
Dec 5, 2011
1,584
the roadie said:
Surely you didn't marry somebody unwilling to learn new stuff? Start regular discussions, teach her things, assign reading material. Bring your life partner up to speed. :yes:

I married someone incapable of understanding anything mechanical. Don't get me started on the times when I tried to teach her to drive a manual transmission.
 

dingle

Member
May 26, 2012
59
Hypnotoad said:
I married someone incapable of understanding anything mechanical. Don't get me started on the times when I tried to teach her to drive a manual transmission.

I thought I was the only one. my wife tried once to drive my old accord. It didn't go too well
 

The_Roadie

Lifetime VIP Donor
Member
Nov 19, 2011
9,957
Portland, OR
The ability to drive a stick shift may save her life someday, or at the very least allow her to escape an uncomfortable situation/location. Or allow her to take the keys away from a drunk friend and drive THEIR car home.

I strongly recommend ANYBODY with a spouse, kid, close friend, etc. who doesn't know how to competently drive a manual transmission, get them taught. It's not frickin' rocket science, and don't let them give up after only ONE lesson.
 

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