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99 Suburban front end noise can't figure out.

1459 Views 5 Replies 4 Participants Last post by  sector

Sorry in advance for the long post.

Last week my 1999 1/2 ton 4WD 160,000 mile burb started making a humming noise from the front end. The noise seems to get louder at higher speeds, but does not go away if you turn in either direction. I initially thought wheel bearing. I jacked it up and everything felt tight. I checked the front diff. It looks like the drivers side seal is leaking so I checked the diff fluid. It was down about 4 ounces. I topped it off and took it for a test drive. It seemed to cure it so I decided to tow the boat to the Islands for the long weekend. About 1 hour into the 2.5 hour drive the noise is back and a little different. You can be driving along and it will sound like something freed up and is revving higher. This is just the way it sounds the tach and speedo stay the same. Other times it sounds very labored although the tach does not drop. No vibration, and no pulling, it brakes fine and goes straight. My gas milage is the same as it always is sucky. I had the window down as I went through Syracuse (where there are barriers) and it sounds like you can hear a tin like clicking that varys with speed. It sounds like it is coming from the driver's side towards the middle of the truck. I made it up and back without incident, but would like to figure this out before a catastophic failure. What do you think?

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Sounds a lot like the halfshafts need to be replaced.
Dont know the terminolgy of half shafts but have had some situations with CV joints. Maybe the same thing as I normally had trucks with the old straight axle(dodge, and older chevy's), but had friends who had similar situations with cv joints. Just my $.02.
I have replaced CV joints in front wheel drive cars. This is not the same kind of noise. I thought with CV joints you get the noise when you turn. This does it on the highway going straight. I think I am going to have to tear it apart.

Anyone know how to get the front axles out of a 99 burb? It is not a conventional differential like the rear. Do you have to split the case, or do the axles pop out when you remove the front suspension?

half shafts, cv joints, meh, its all the same.

Replace the wheel bearings and the front axle shafts (they aren't rebuildable). Might as well do both while you are in there. On the newer trucks there is no locking hubs, your axleshafts always spin, the chevy trucks have an axleshaft that uses a cv joint that is like a toyota birfield joint, its kinda hard to explain, but when the rubber boots rip and road grime gets in there they get noisey. They don't tend to click like a FWD cars do....

take off the wheel, caliper, rotor, wheel bearing, shafts, replace.

Have a 36mm socket handy, you will need it to pull the nut off the axle shaft that holds the wheel bearing in place.
Check the transfer case, had the same noises in my '99 3/4 ton Suburban. Had to replace the transfer case.
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