weird whine

anybody know why i would get a whine from maybe tranny or engine at about 3000-3700 rpms on hard acceleration (passing on highway)before or after the rpms no noise everything drives fine and shifts fine, i just have the whine for that little bit:uhoh:replaced the pinion bearing 70 miles ago and rearend looked fine.
I have a 1998 dodge quad cab 4x4 w/ 5.9, dual exhaust after muffler. (D/K what kind, i bought the truck like that)

do you get the whine when you rev p to those rpms in nuetral? try that to determine wether it is in drivetrain or engine.

do you get the whine when you rev p to those rpms in nuetral? try that to determine wether it is in drivetrain or engine.

ya, i left it in park and rev up to about 4000

I have heard alternators do that as well as idler pulleys/ tensioner pulleys. Check these with a piece of hose up to your ear and fish around under the hood while somebody runs the throttle.

I have heard alternators do that as well as idler pulleys/ tensioner pulleys. Check these with a piece of hose up to your ear and fish around under the hood while somebody runs the throttle.
Itsounds more like its coming from under me to behind me, i think. my fan bearings i know are bad, but i would think that it is to far in front for it to sound under me?

I would start with that. Sound can be very deceptful. It can travel through the body or drivetrain. Pick up a stethascope or use a long screwdriver, put the handle to your ear and hold it against the engine, it acts like a stethascope and works quite well. If the noise is in park. it is probably an engine pully bearing somewhere. Check the idler pulley, they were common for going bad. let me know what you find.

I would start with that. Sound can be very deceptful. It can travel through the body or drivetrain. Pick up a stethascope or use a long screwdriver, put the handle to your ear and hold it against the engine, it acts like a stethascope and works quite well. If the noise is in park. it is probably an engine pully bearing somewhere. Check the idler pulley, they were common for going bad. let me know what you find.

I'll try that tomorrow. If I dont hear it in park,how else can i check if its somewhere in the drive train? Also, do you know why i would get spark knock if i let my truck idle for ......20 min. or more? If i just start and go i dont get any(hardly any). Only when it idles for a little bit. I'm in Wisconsin so its cold out right now, thats why i let it idle for a little bit.:uhoh:

I'll try that tomorrow. If I dont hear it in park,how else can i check if its somewhere in the drive train? Also, do you know why i would get spark knock if i let my truck idle for ......20 min. or more? If i just start and go i dont get any(hardly any). Only when it idles for a little bit. I'm in Wisconsin so its cold out right now, thats why i let it idle for a little bit.:uhoh:How old is your oil and haow thin are you using? I'm in Montana, alot of people use a thinner viscosity in the winter because of the cold, I do not. It makes it easier to turn over cold but once it warms up it stays a little thinner, even the multi viscosity. Just something simple to check before getting to the bigger stuff. And what does the oil pressure read when it knocks?

How old is your oil and haow thin are you using? I'm in Montana, alot of people use a thinner viscosity in the winter because of the cold, I do not. It makes it easier to turn over cold but once it warms up it stays a little thinner, even the multi viscosity. Just something simple to check before getting to the bigger stuff. And what does the oil pressure read when it knocks?
I dont know, i just bought the truck thats why i didnt notice it cuz the guy met me at a spot. it could use an oil chnage it is dirty, but the oil pressure is good. i plan on doing it thurs. what viscocity do u recommend. i use castrol for brand and i planned on putting 10w30 or maybe even a synthetic

when I reach @12ok mi. I usually bump up to 20-50wt oil. Some people don't agree, but no matter how good an engine, the tolerances increase with wear. I would suggest running a seafoam oil treatment through it first. This will help clean a lot of sludge build up out of the engine and open the channels for oil flow. You can use whtever oil you want, but I do not like castrol, it has been shown to rate very low, as in it leaves a lot of sludge behind. I use Napa brand. I know that sounds stupid, but it is produced by valvoline, same oil, and valv. rates good. I use synthetic on new engines but not on worn. It does lubricate very well, but it gets thin quickly and on high mile engines, you need something to take up the space created where things loosen up. That is my take on it. Oil doesn't just lubricate, the engine is designed with space to allow oil to pass to lubricate, when that space is increased with wear, something has to fill it.

when I reach @12ok mi. I usually bump up to 20-50wt oil. Some people don't agree, but no matter how good an engine, the tolerances increase with wear. I would suggest running a seafoam oil treatment through it first. This will help clean a lot of sludge build up out of the engine and open the channels for oil flow. You can use whtever oil you want, but I do not like castrol, it has been shown to rate very low, as in it leaves a lot of sludge behind. I use Napa brand. I know that sounds stupid, but it is produced by valvoline, same oil, and valv. rates good. I use synthetic on new engines but not on worn. It does lubricate very well, but it gets thin quickly and on high mile engines, you need something to take up the space created where things loosen up. That is my take on it. Oil doesn't just lubricate, the engine is designed with space to allow oil to pass to lubricate, when that space is increased with wear, something has to fill it.
I have 105000 on the truck so i'll stick w/10w30 for now, but i'll run the treatment on thurs. when i change the oil. Do you think thats why i get that clattering only after it idles?

I ran seafoam down the throttle body and changed the oil and put Lucas in the crankcase. it seem to be ok so far. thanks.