Guys,

I have been doing a lot of commuting lately, about 1,000 miles per week. I have a 98 T100 SR5, 4wd, extended cab and it's making a strange intermittent noise. It is coming from somewhere in front of the passenger compartment. The only description I can give is it sounds like a dry bearing spinning on your finger. It is an automatic, otherwise I would suspect a throw out bearing. I have checked my front hubs and nothing feels warm. It is intermittent at any speed. I can't tell if it's coming from the front drive train or the engine compartment. No check engine lights and everything is working fine. It even did it before it got cold outside. Any ideas?????
Thanks,
Winkel <img src="/forums/images/graemlins/confused.gif" alt="" />

Speedometeter cable most likely.. You can lube it with some graphite and it will help.

Sometimes the heat shields around the exhaust manifolds get cracks in them and vibrate and make noise. Usually this is rpm-dependent. If that's the cause, a hose clamp usually is an easy fix to quiet it.

Guys,

I had another not-so-pleasant thought. When I changed my timing belt 40,000 miles ago, I didn't change the automatic tensioner pulley. Is there a possibility that it is making the noise, or do those things go forever? Didn't really notice it coming home tonight.
Any thoughts?

Thanks,
Winkel

You know when I did my timing belt my pulleys weren't perfectly quiet, I was concerned about this, but I put new belts on and tensioned them properly putting everything back together and that quieted things down a bunch.

Possible you did the same as I did - told my mother-in-law to get out of the vehicle? <img src="/forums/images/graemlins/lol.gif" alt="" />

Guys,

I've had another thought. It is definately related to vehicle speed, not engine speed, so it's in the drive train. It does change when I hit bumps in the road. I think it might be the carrier bearing in the rear drive shaft. I'm not sure if that's what it's called, but it's the bearing between the two drive shaft pieces.

Can this be lubed? Do they go bad often? If it goes completely can it still be driven? How hard is it to change and can you get one at a local parts store? Just a thought, any feedback would be helpful.

Thanks,
Winkel

They can't be lubed and they do go bad but not that often. They are expensive ($100-150?) and I'm not sure if your local parts store carries it and I've never changed one so I can't comment on the difficulty (doesn't look that bad though). I don't think it will hurt anything to keep driving it for the time being...

Carrier bearings are pressed onto the yoke of the ujoint shaft. You break down the drive shaft, use a drift and hammer and gently tap on the bearing inner race until it comes off the yoke. Reverse the process to install. You might find a replacement that had a grease joint in it. Most older American units are greasable, so I would expect the units that are not thelowest buck to have such arrangements