2002 4Dr 4x4 Blazer, mostly stock.

When driving, it does not need to be in 4x4 and the vibrations do not begin until around 100 kmh but if I take my foot off the accelerator and just coast, I can still hear/feel it as the vehicle slows.

I have done some narrowing down already...

I put it up on blocks and ran it with only RWD = 0 vibration.
In 4x4, vibration occurs around 100 kmh with some whirring noise.
The vibration is felt in the cab and through the steering wheel forward of the front seats but difficult to pin point.

I had one of the girls take it up to 100 kmh several times with my hands placed on front differential and the transfer case but it was not as noticeable and although I felt vibration, it did not seem to be the source.
The front drive shaft is firm and does not flex at the CV and the Universal seems good, although there is a little slop when turning it.

I can turn all wheels and drivetrain by hand while suspended, in neutral, while running and not without any resistance felt.

I thought the whirring might be gear gnashing (think that is what is called) but again, I thought I would hear/feel that more easily while under the vehicle.

I installed a new front passenger side axle recently and I suspect it because of the mere coincidence of time line but am now stuck, not knowing how to eliminate any other parts.

At first, I thought I might be able to eliminate the front tires and wheels but am now second guessing that thought.

Might have to buck up for this one instead of doing the back yard mechanic thing. PLEASE HELP ! :icon_nut:

 

this is just a thought but I had a similar situation with my wife's 95. when you got to 50 MPH plus and took your foot off the gas and coasted there was a whining noise. the truck had 250,000 miles on it. I got in the cargo area and had her drive it on the highway and it was the rear end making the noise, did it in and out of gear. maybe that helps?


a day later she broke a water hose and kept going till she melted the engine.

 

That's one way to "eliminate other parts."

 

yeah, the funny thing is she called me at work and said "hey, the temp gauge went all the way up and after a few miles it went all the way down, but the truck is still running"
at that point it was to late, as I was yelling to shut the thing off and pull over.


she said the temp gauge went down so she thought it was ok. I told her the temp sensor can't read water temp if it has no water in it to read. oh well, at least I didn't spend $1200 on a new rear the day before.


good luck with your noise.

 

I had already eliminated the rear drive gear whilst not in 4x4 mode.

It is whirring noise, not whining.

Thanks anyways.

 

3 button or 4 button 4x4?


Have you tried rotating tires to see if the vibration changes location?

 

I have the 3 button, I do not have the auto 4wd feature.

I have not yet tried rotating tires to see if the vibration changes and will, hopefully tomorrow.

Thanks

 

besides the thots on tire balance and maybe a bent rim - everybody seems to miss the quote above - there should not be any slop in drive line

 

There shouldn't be, but it also shouldn't be causing any vibration while driving in 2wd with a 3 button transfer case. That's why I asked about which transfer case he has before bringing it up.


So yes, that slop should be fixed, but I doubt it's the cause of the vibration.


Dino, you could remove the front driveshaft to make sure that's not what it is. If the vibration goes away, then you should look into the 4x4 system to see if the front axle is staying engaged while in 2wd

 

Sorry all, been busy and have not yet figured it out.

Rotating tires did not result in change.

A friend who I know of FB told me the front axle I replaced could be the culprit. He used to have a shop but moved on to greener pastures. He said he has had instances and "just because it is new doesnt mean it isnt the problem". More test to come. Thanks for your input all and "if/when" I figure this out I will post the results. (y)