I can't find anything definitive on the internet, so having done my due diligence without success, I am sure somebody here will have (at least) an educated guess.

Preamble: My 97 Blazer died and I bought a 98 Jimmy 4wd from a mechanic repo. Lotsa work already done on it last December but it sat along time and I knew I'd have to put more in if I want a reliable ride.

The Problem: After a highway run of 110kph on cruise for ~ 5km, kicking the gas to take off the cruise and applying light brake, a loud rumbling whine/roar starts up from the passenger front. Sounds like a rumble strip at speed. However noise doesn't quiet down with slower speed, it gets louder but slower like a growl.

The Fix: First I changed out the worn out studded snows that had been installed last winter. No change.

Then changed out the wheel bearing. No change.

The brake rotor(s) had been turned and new pads last year.

Possible clue: Reversing 20 ft fixes the noise 'til next time.

There are a number of people wondering how this puzzle solves out. Anybody have any ideas?

 

My first thought was the wheel hub assembly... Check and or change the front Differential/Gear oil and the Transfer Case fluid... Just a thought

 

just a weird thought...if this is a 3 speed 4wd system, check and see if the slip shaft is engaged...if not..forget this..If so...chime back in and we'll go from there...Jerry

 

Thanks for the suggestions. I will have my mechanical person check the levels in the differential and transfer case.

Jerry – I think I see where you're going with that thought but I'm not sure what you mean. Or how to do it. Can you elaborate a little?

 

grab the slip shaft/half shaft going to the front differential and see if it is free in 2 wd or....see if there is any difference in its feel...from 2wd to 4wd....if locked in-in 2wd..I would look closely at the transfer case switch..Jerry

 

Reporting back.
Other than draining & refilling the transfer case and the earlier work, I did nothing more to it and it seems to have fixed itself.
Maybe it just had to work itself in - it had been sitting since last December.
So far- so good. Thanks to all responders.

 

Glad 2 hear so far so good on the repair... It is always great when someone updates their problem is resolved