Weird noise coming from 4wd

[rolfsent]

When I engage 4wd in my 99 Denali it starts making this strange groaning noise from the front end. As soon as I disengage 4wd it stops making noise. It almost sounds like rumbling/groaning noise, not sure how to explain it better. Also not sure if it's related but I just installed 4 Bilstein HD's on it and now the front end on the left side makes a terrible rattling noise.

 

[SunlitComet]

check over your driveshafts and differential to see if something is broke or the case is cracked. Did the groan just start?

 

[rolfsent]

The noise has been there since I bought it a month ago. I've just now gotten around to checking it out. The 4wd engages and turns all 4 wheels just fine, but it makes a noise. I think a better way to explain the noise is almost like If you had chunky all terrain tires on the highway, just only coming from the front.

 

[Bigbody250]

I would check fluids, if it's not clanking it sounds like its just loading up the front. Check your tires, with a measuring tape... If you have different brands or the front are worn down it will cause that.

 

[rolfsent]

I would check fluids, if it's not clanking it sounds like its just loading up the front. Check your tires, with a measuring tape... If you have different brands or the front are worn down it will cause that.

I just got brand new Falken Rocky mountain ATS tires installed last week, so it's not the tires. How do I check the fluid?

 

[Bigbody250]

There is a plug on the back of the transfer case and I'm not sure where on the front diff but shouldnt be hard to find... I just got my 98 Tahoe a few days ago, still going through it

 

[taylorjm]

Not sure about your year, but I know that in my 03, if I have it in 4hi or auto 4wd, I get a groaning from the front end too. I've had the differentials torn apart by 2 shops and they both said it's normal. The dealer said the sound is also normal, even though I know it wasn't like that new. I know a few other people on this and other sites also have the groaning and are chalking it up to being normal. I do have one friend, and I need to confirm this, but I believe they had the transfer case rebuilt after it exploded and said the groaning stopped. I just have to double check that it was the transfer case that was rebuilt and not something else.