Noise from the back?

[ukrkoz]

i got bad bearing chirping noise from behind me, every time i touch accelerator pedal. well, not every time, but most times.
absolutely bad bearing noise. scritchy chirp.
i have good guess what it is, as there's only one small bearing behind me that can do this noise, but will listen to opinions.
2000 Silvie, LT, extended cab. comes from about behind my right shoulder.

[jdmccright]

Lots of bearings back there to scrape/chirp. Could the the driveshaft carrier bearing, a u-joint going bad, or a rear wheel bearing. Does it only scrape once when accelerating or is it continuous until you let up on the throttle? You might try putting the truck up on blocks/stands and have someone blip the throttle while you listen for the noise.

BTW, congrats, you are my 1000th post.

[Airjer_]

I think I would pull the drive shaft and at least check the u-joints to make sure they are nice and smooth as well.

[ukrkoz]

well, i think i know undercarriage well enough.
where i sit, and i am all the way back as far as the seat goes, driveaxles are ahead of me.
trannie output shaft is right under my buttocks, and that the last small bearing in powertrain that way.
i do not have carrier bearing, it is single piece driveshaft.
i had rear wheel bearings checked out 3 mths ago, confirmed good.
noise is coming from the back, from behind the right shoulder direction, sort of towards the rear.
it is just when i start accelerating, for about 5 seconds. pitch varies some. in 3-5 seconds it's gone. like i said - does not do it all the time.
i called my buddy mechanic, and he is positive it is not fuel pump. that was my main concern.
the rest of it - i'll scope it tonight. as far as it is not fuel pump and i do not get myself cought on a freeway, i am not worried.

thank you all.

ok, an update. i took truck out for a spin with window down. it does mostly fine. i had one instance of ratlle that sounded streight like loose splash shield on brakes. hopefully, i'll make it home with this, as splash shields are held in place with caliper bracket bolts.
what concerns me more is that i heard 2 instances of a hiss. just like fluid squeezed through narrow passage, or stretched belt rub. except that i have brand new belt installed maybe 1.5 mths ago. with windows up, could have been confused for bearing squeel.

[MikeD266]

Ukr, timing in life is everything. I'm trying to figure out what sounds like a similar noise on my '99 Z71 ext cab. Have a squeak that mainly happens when I'm on the gas and drive train is under load. Squeak goes away when I let up on the gas. Also can't make it happen with the rear end up on stands.

Pulled the rear shaft and replaced the rear u-joint. That wasn't it. No discernible side/side wiggle in the rear wheels at all. Sounds like it's rotating faster than the tires so I had focused on the shaft. Replaced one front end bearing last fall. Have to do the other FE bearing soon. Both rear rotor splash shields are rotted but they aren't interfering with the rotors themselves.

Rear pumpkin juice level seems fine as well so I'm currently at a loss. Guessing either the rear yoke or a rear wheel bearing. Just can't seem to replicate it with the truck standing still.

Thoughts anyone?

[j cAT]

Originally Posted by MikeD266

Ukr, timing in life is everything. I'm trying to figure out what sounds like a similar noise on my '99 Z71 ext cab. Have a squeak that mainly happens when I'm on the gas and drive train is under load. Squeak goes away when I let up on the gas. Also can't make it happen with the rear end up on stands.

Pulled the rear shaft and replaced the rear u-joint. That wasn't it. No discernible side/side wiggle in the rear wheels at all. Sounds like it's rotating faster than the tires so I had focused on the shaft. Replaced one front end bearing last fall. Have to do the other FE bearing soon. Both rear rotor splash shields are rotted but they aren't interfering with the rotors themselves.

Rear pumpkin juice level seems fine as well so I'm currently at a loss. Guessing either the rear yoke or a rear wheel bearing. Just can't seem to replicate it with the truck standing still.

Thoughts anyone?

lift both rear wheels off the ground and rotate all the drive shafts for play...it won't make noises with no load...also look for discoloration of the U joint,,,leakage rusty lube weeping out of the seals..

if the rear wheel bearing is bad it will start to leak gear in time..same with the pinion ...

[ukrkoz]

Originally Posted by Airjer_

I think I would pull the drive shaft and at least check the u-joints to make sure they are nice and smooth as well.

And the winner is..........
Airjer!!!
i started rolling truck in the driveway, with window down and then door open. there was a loud pop every time i'd shift from reverse to Drive and back. it'll come right from right behind/below me. POP! POP! like someone was snapping tin.

out of curiosity, i pulled driveshaft out. slip yoke u-joint was busted to the point of barely moving on 2 bearings. one bearing cap was off. loud, crunchy noise every time i tried to move it.

9 bucks lifetime from Schucks. WITH ZERK!!! i love those little bastards, they make things run much longer.

[Airjer_]

[ukrkoz]

Originally Posted by Airjer_

ain't you proud of yourself?

good guess, buddy!

[jdmccright]

Well i did mention u-joints, but good to hear you found it. Heck for that price I'd change both out.

[Airjer_]

Originally Posted by ukrkoz

ain't you proud of yourself?

good guess, buddy!

Absolutely you should get some credit JDM!

Like Richard Petty used to say I'd rather be lucky than good any day!

[MikeD266]

Well crap... NOW what am I going to do.... Hey AirJ...You're good... Think you could take a guess at my problem now? LOL....

j cAT, just did all 4 u-joints not 15k mi ago... Tarnished... But not overly concerning... I just can't pin down the source if there's no load on the train... No noise from anywhere with it on stands and both rear bearings look like they're still ok.. No weeping anywhere... No obvious issues... Both spin OK...

Guess I'm off to a shop for diagnosis....

[jdmccright]

How's about a 1/2 point for the assist? Thanks, Airjer!

[ukrkoz]

Originally Posted by jdmccright

Well i did mention u-joints, but good to hear you found it. Heck for that price I'd change both out.

guys, i most appreciate EVERYONE'S help. i can't tell how much time and $$ was saved for us, as a family, by listening attentively to what forums say. those are real pains and experiences, not just "let's make quick buck" approach.

THANK YOU ALL.

[j cAT]

Originally Posted by MikeD266

Well crap... NOW what am I going to do.... Hey AirJ...You're good... Think you could take a guess at my problem now? LOL....

j cAT, just did all 4 u-joints not 15k mi ago... Tarnished... But not overly concerning... I just can't pin down the source if there's no load on the train... No noise from anywhere with it on stands and both rear bearings look like they're still ok.. No weeping anywhere... No obvious issues... Both spin OK...

Guess I'm off to a shop for diagnosis....

noises are hard to describe some times...pitch frequency etc....an experienced tech,,,will know very quickly what it is....

go for a ride for 5 miles then stop and feel the u joints for getting hot..a hot joint will be the bad one..
what do you use for grease and how often..? lube every 6 months,,, especially before winter..