Drivetrain Rumbling

[gijoecam]

Drivetrain Rumbling help ASAP!??

Need help ASAP:

Vehicle: 98 Explorer Sport 4.0 SOHC, auto, Control Trac 4wd.

I've got a rumbling on the drivetrain that has gotten progressively (and noticably) worse over the last two days. I thought it was a wheel bearing, but I have the thing up on stands right now and everything is tight. if I drop it into gear and let the wheels turn, I can feel the rumbling in the floorboards, but can't seem to pinpoint it... I've checked the front friveshaft and everything seems to be tight... the front u-joint has zero slop in it (haven't checked the rear one on the front driveshaft because it's still encased in ice and currently thawing in the garage). It doesn't appear to be low on gear lube in the diff (it's not leaking), but I plan to double-check that next.

CVs are tight with almost no slop whatsoever....

The thing I noticed on the road is that it seems to get marginally worse when I make a left turn, marginally better when I make a right turn...

It sounds like it could be the pinion bearing on the front driveshaft... how can I check that?

Also, is there a way to disable the control-trac feature to verify that it is in fact something in the front half of the drivetrain? I tried pulling fuses, but none of them seem to have the desired effect...

Any ideas on other places to look?

I'm stumped on this one... I thought with the amount of grinding I'm feeling it would be obvious, but it's not... help?!!?

edit: forgot to mention that is seems to be most noticable when decelerating or accelerating between about 10 MPH and 40 MPH. Above that, it's drowned out by road noise, and below 10, it seems to just vanish. There is no pulling to either side at any speed, and if I just spin the wheels by hand, everything seems to be just fine... no noise, no play, no slop at all... Also, when driving odwn the road, it doesn;t seem to make any difference if I engage 4wd and corner... it doesn;t get any louder or quieter with 4-hi engaged, so I'm leaning away from the drivetrain issue... could the bearing(s) be making the noise, but not have any slop in them? That would be a new one for me...

Totally stumped still... ideas?

-Joe

 

[gijoecam]

OK, got it... it was the driver's side wheel bearing gone bad. I put it in drive and held the right front wheel and the noise got louder and faster. when I held the left front wheel, it stopped, so that narrowed it down to that side. Then, I had a shot of it being the bearing or the CV, but the CV was intact and had no play in it, and turning the steering wheel to the side made no difference, so I suspected it was the bearing. $150 later, I'm back in bidness!

Maybe this stuf will help someone else along the way... not bad for a long-shot, eh?

-Joe