Calling all auto mechanics

[mdwatt]

I have a 1993 s10 blazer 4x4 with 191K miles. I have a problem with a noise and vibration in the front end. Its like when you drive over rumble strips, only its almost all the time. Its usually intermittent, but every few seconds driving down the road I get the sound again. I replaced the front wheel bearings/hub assembly, but this did not fix the problem. I also inspected the front CV joints and found no problems. The 4 wheel drive engages and works in 4 hi and lo with no noticeable issues. I'm at the end of my expertise. Any other ideas? Thanks in advance for the help!

 

[bhelms]

The major problem I had with my '95 S-10 PU (technically a T-10) was that it gobbled-up ball joints over its 185K mile life. I think I had all 4 replaced at least 2 times each. The main symptom was clunking while going over bumps and in turns, but the whole front end was "loose" until they were replaced and some vibration in the front would suddenly be cured for a while until the replacements aged as well. Since they would go bad gradually it was hard to notice until they were getting really bad. I doubt it's related to your problem, but since you didn't mention ball joints I thought I would. As I understood it, this is a chronic S-10 problem spanning a number of model years. Actually, in 191K you have probably had to replace yours at least once...!

 

[Bob Haller]

wierdly check the engine mounts. my van had that symptom and it went away after finally replacing marginal engine mounts... put on emergency brake, hold foot on brake, move gear shift from forward to reverse giving it some gas. a bang on engiune moves a lot tells you they are bad. marginal bad are the worst to diagnose

did you remove the CV joints to inspect them?

they can look fine but be worn and hard to see the wear?

 

[mdwatt]

I looked as closely as I could at the CV joints without removing the boots. They spin freely in all directions with no binding, and there is not grease coming out anywhere. The CV boots are still very rubbery and show no signs of dry rot. It's possible that it may be a U-joint in the drive shaft between the transfer case and the front pumpkin. I'll be checking that next.

 

[Van]

Does the front end seem to have more up and down travel when going over bumps?

I'm not sure if removing the front drive axle would help but if your getting a rumbling I'd still suspect the gears or one of the spindles. Have you checked the fluid in the axle to see how it looks or if its drained out possibly?

Another thing I'd look at would be the brake pads and calipers, a loose or broken caliper can rattle at speed.

Inspect the ball joints and tie rods, also look at the power steering rack.

Does the rumbling only happen while in motion? Can you try sitting parked and bringing the engine up to driving revs for a minute or so to see if it happens with a higher rpm? This could indicate something else such as a loose belt or a pulley going bad or something elese associated with the belt system.

 

[mdwatt]

It only happens when driving, and mainly when coasting. Though once the truck has been driven for a while, it can happen while the wheels are under power as well. I checked the fluid levels in the front and rear differentials, and had to add some to the front, the rear was ok. The splines in the front half-shafts looked ok when I had them out today to replace the front wheel bearings and hubs. It has to be either a CV joint going bad, but I can't see it because of the boot, or a U joint in the front drive shaft from the transfer case to the front pumpkin. Ball joints need replaced, again....., but the noise is not limited to going over bumps or turning, so ball joints are out. Tie rods are good, and there is no excessive play in the steering system, or abnormal vibration thru the steering wheel. Picture driving down the highway at 55MPH and you drift too far to the left or right and you run over the rumble strips on the side of the highway. You get that distinctive sound and the vibration thru the floorboards. It's exactly like that. And before anyone asks, yes I'm keeping it between the lines. It's somehow related to the drivetrain, because when I go to stop the sound changes in tone and intensity as my speed decreases. I plan on doing further troubleshooting tomorrow afternoon. I'll let you know what I find. Thanks for all the replies!

 

[Bob Haller]

I looked as closely as I could at the CV joints without removing the boots. They spin freely in all directions with no binding, and there is not grease coming out anywhere. The CV boots are still very rubbery and show no signs of dry rot. It's possible that it may be a U-joint in the drive shaft between the transfer case and the front pumpkin. I'll be checking that next.

you cant inspect CV joints without disasembly and deefinetely removing boots

its like seeing a gorgeous gal, saying lets get married, then finding out she is a moron, and doesnt like sex........

looks can be decieving

 

[Bogy]

Have you looked at your tires? How are they wearing? Not only a clue to suspension problems, but noise/vibration are often coming from the tires themselves.