low pitch rattle <2300rpm & >50% throttle

[EstoMax]

hey guys,

ever since i bought my truck a few months ago i have noticed a low pitch rattly noise (not really metallic) from possibly the drive shaft (carrier bearing?) when im in the first 3 gears and below about 2300 rpm and also above 40-50% throttle. If i accelerate slowly then the noise is not there, or if i go high rpm i don't hear it either. IF i do low rpm and high throttle though there is this intermittent rattling like something was flopping around down there.

anyone else experience and solve this?

cheersMarko

[Rev_D21]

I am confused by 'low rpm and high throttle' statement. Can you explain that further?

[JC87HB]

im going to guess that he has the truck in 3rd gear flooring it but only going like 1400 rpm cause hes going 13mph? idk lol

[seang]

Well, Esto drives a boosted 240, so I doubt he is lugging the engine. I'm still at a loss of what exactly it could be.

[snowyred180]

Is it stock? Like a heat shield rattle or something? I found a bolt wedged in between my exhaust and the sheild. Ripped off, problem solved! Yay!

[EstoMax]

ill try to catch it on my cam, though i doubt it will work :P

basically... accelerating from a stop, if i go slowly, like less than 40% throttle, it will be fine, and first gear actually doesn't cause the noise either because it doesn't load the engine enough.

second and third gears though, if i'm like 1500-2300 rpm and floor it, i can hear this rattling noise, doesn't really sound exhaust related, because its not distinctly metallic. I was just wondering if the carrier bearing or some driveshaft related joint thats worn out makes a similar noise, but i guess im confusing u guys

in a way i suppose it could be 'lugging' but the engine sounds fine. this isnt some honda that can't drive below 2-3k rpm!

[snowyred180]

Hrm, any idea where it's coming from... Transmission, engine, under car, etc? Maybe have someone rev it in neutral and try to track a general vacinity where it's coming from? I'm picky about squeaks and rattles. So many times it's been the heat shield. I did have an a/c line that was loose and hitting the firewall once. It made kinda a low-pitch noise, just whenever. Any recent work that might have caused it?

Good luck!

[EstoMax]

yea it doesn't do it in neutral, only under load and below about 2300 rpm.

it is coming from the back it feels like.. thats why i started poking about the carrier bearing. What does that things failure sound / feel like?

i will try to get a video clip of it tomorrow evening

[kibatheloanwolf]

Hmm have you checked the shield that goes on the bottom of the cat? I've gotten rocks in there before and they rattle

[Rev_D21]

If you are making the engine labor under hard throttle but it's in too high a gear I would imagine that it's the whole body of the truck shaking because of the extra load on the engine. Mine does it if I up shift too soon for the speed I am driving at (ie 25mph in 4th gear for an extreme example...not that I would ever do this). Causes the whole truck to shake.

[EstoMax]

well.. i tried to video the sound, but it won't pick up.

it's definately not lugging of the motor, because it does it in 2nd and 3rd gear only. i can floor it in 4th or 5th up a hill at 2k rpm and it will sound ok... albeit stressed but thats an engine thing.

i will check out heatshields underneath and otherwise ignore it for now.

dont mind my rambling thanks for input though!Marko

[RT22]

something is loose do a good under bed inspection if it is coming from the back. exhaust anything that is bolted could be loose and rattling. I hate that stuff it can be a pain to find, get a buddy to drive it and ride in back and listen and isolate it.

[EstoMax]

well im not sure why i didnt notice before but the carrier bearing in the middle of the driveshaft is missing about 50% of the rubber, i can jiggle the driveshaft a good half an inch in it haha.. i bet that's it.

i am guessing this thing here:http://www.oreillyauto.com/sit...C0362

damn expensive for a rubber piece. is there some aftermarket option / polyurethane replacement for this? how much are one piece driveshafts?

CheersMarko