96 Noise from (truck's) rear end

I have a noise coming from my truck's (1996 Tacoma) rear end. It's somewhere between a whirring and a grinding, it only gets noticeable above 40 mph, and it seems to oscillate, it's not constant.

The rear diff is full, I just greased the 3 zerks on the rear driveshaft, when the wheel bearings go they usually take the axle seals with them and spray gear oil all over your tires, so I think it's probably not the wheel bearings but I'm not sure. It's been mentioned that it could be the pinion bearing, but I'm not sure how to check that.

Any other thoughts?

 

It's probably the carrier or pinion bearing

 

I've had the wheel bearings go out and the seals remained intact. But my symptoms were different than yours (more clunking at low speeds)

 

Just because you greased the ujoints doesnt mean they arent worn. If you try to wiggle the rear ujoint do you notice any play/movement? You can also jack up one side of rear or both and check your wheels for play. Same with the other ujoints, check for play/movement. Carrier bearing will move but if the rubber center is worn the bearing is probably bad.

 

Wiggle it back and forth I assume, not twist it?

I'll check the carrier bearing.

I should say, truck has 287k on it, well maintained, but not immaculate.

 

All directions. Should be pretty solid.

 

My $ is on the carrier bearing.

 

Seems real solid, as do the u joints. I can twist the driveshaft a little bit where it goes into the third member.



Do I just start replacing stuff until the noise goes away? Seems time consuming and expensive.

 

Sometimes that's what you have to do. I'd start with the easiest cheapest/easiest item first (carrier bearing), and go from there. I'm starting to think this could be rear wheel bearings though. If they're original (at 287k miles), they've gotta be close to toasted if not already.

FWIW: Spicer makes a carrier bearing that is the same part as Toyota sells, but it costs 1/3 of the price. I found mine perusing around Amazon.

 

Replaced the carrier bearing, noise is still there. Any chance it could be a brake dragging? The wheels don't have any play in them, if they did I'd go right to the wheel bearings.

At this point the possibilities seem like pinion bearing, wheel bearings, or U joints. What do you think the next easiest/likeliest thing to replace would be?

 

Doubt it's a brake dragging, but it couldn't hurt to try and jack up the rear and and just check that the shoes are dragging equally on the drums.

I'd try and determine how to check the pinion bearing. I'd assume you just put the truck in neutral and then twist the driveshaft back and forth and determine if the pinion seems to have to much rotational "slop".

Did you ever say if the rear wheel bearings have ever been done before? When my wheel bearings were on their way out I remember noticing that with the rear jacked up, I could pull the rear wheels out towards me (away from the truck, just a small amount). As if the hub/axle assembly was actually sliding in and out of the bearing assembly. Made me thing my wheel spacers or lug nuts were loose, but re-torqued both and that symptom remained. Can't do that now with the new ones in.

And somehow mine never had side to side (3 & 9 o'clock) or up and down (6 & 12 o'clock) play in them

 

I dug through the maintenance records I got when I bought the truck and 11k miles (and 10 years) ago, there's a note from a dealer service department saying that "customer states there is a noise from the driveline" so it seems like the noise has been going on for a long while at least.

That same service, both rear wheel bearings were done, and something was done with customer supplied parts that's described as "install customer's rear diff" so it seems like it had a new diff 11k ago.

5k ago, the rear diff was "serviced" and a note was made to check the drain plug for metal shavings.

That's all I've had the chance to go through so far, I want to see if the u joints have ever been replaced, but I suspect they have not.