Tranny issues?

[Sharpe]

Recently a strange humming noise/whine has been coming from somewhere beneath my truck (the crewcab) and I'm not sure what it is. It sounds like metal scraping on metal, and it only occurs when applying power (i.e. not when coasting). It has been speculated that it is my tranny but it seems to be functioning normaly. I put some of the magic Lucas stuff in it and did not affect the noise at all. The noise is unbearably loud and doesnt seem like its going to go away on its own so anyone have any ideas on things to look for or cheap items to try replacing? The truck has 170k on it and has a 4L80E 4 speed auto tranny. Its possible that this is the original tranny in the truck, and if thats the case it has had a long, hard life.

[DRAGOONRANCH]

I would change the fluid and filter first off.

[fbronco86]

Recently a strange humming noise/whine has been coming from somewhere beneath my truck (the crewcab) and I'm not sure what it is. It sounds like metal scraping on metal, and it only occurs when applying power (i.e. not when coasting). It has been speculated that it is my tranny but it seems to be functioning normaly. I put some of the magic Lucas stuff in it and did not affect the noise at all. The noise is unbearably loud and doesnt seem like its going to go away on its own so anyone have any ideas on things to look for or cheap items to try replacing? The truck has 170k on it and has a 4L80E 4 speed auto tranny. Its possible that this is the original tranny in the truck, and if thats the case it has had a long, hard life.

Kinda sounds like a u-joint or the drive line bearing

PS always check the easy stuff first.

[StevenAg03]

does your truck have a drive shaft support bearing? Im drawing a blank on the name of it, but it does around the driveshaft and mounts to the frame. mine went out in my truck and it did the same thing just before it ripped itself apart.

[TMatheaus]

does your truck have a drive shaft support bearing? Im drawing a blank on the name of it, but it does around the driveshaft and mounts to the frame. mine went out in my truck and it did the same thing just before it ripped itself apart.

the carrier bearing, when riding in it this weekend it sounded like a u-joint from when you were shifting from park to reverse, so go with those 2 options first, may be an easy fix that way

[Sharpe]

Yes it has a center support bearing (thats what they call it at the parts store, I'd always heard it called a pillow block but they looked at me like I was retarded when I asked for one). It has a decent klunk when shifting into gear so I'll check the u-joints and support bearing tomorow. I figured if it was them there would be some vibration but hopefully it is just them.

[agjohn02]

parts store monkeys usually look at you weird when you use the right name for something. it actually is a pillow block, just not in the automotive world. carrier bearing is what ive always known them by.

[Doug Krebs]

Kinda sounds like a u-joint or the drive line bearing

PS always check the easy stuff first.

yeah, we did this once with my blazer. I thought the detroit was making noises. Took of the rear drive shaft and one of the u-joints was toast.

[CheapJeep]

I'm not sure if obs chevy's are like the new one's where the front driveshaft spins all the time? Maybe slop in the chain on the t-case? I doubt it'd be worn c.v.'s, but driving home in 4 low can do some wierd things. But like everyone has said, could be the u-joints.

Edit- Again on the t-case, I had problems with mine when in 4hi/low, turned out it was the same problem that Grayson talked about below.

[Graystroke]

well, when mine made a crap load of noise about a year ago it was the snap ring on the rear output of the t-case that let go. this piece of shot part cost me a grand to rebuild the case. W/ no snap ring the t-case chain decide to slap the the planetary gears and wreck havoc on all the internals. Mine made noise while accelrating and got real bad after a hundred miles.

[Sharpe]

Well I took all 8 feet of rear driveshaft out today and the u-joints are fine and the center support bearing appears to be ok so I put them back in. The rear pinion seemed like it might have some excessive slop in it though, so I drained the diff and didnt notice any metal shavings or anything out of place. So all in all, my 2 hours of work turned up nothing...

I think I will change the tranny filter and fluid tomorow as well as the t-case fluid.

[fbronco86]

yeah, we did this once with my blazer. I thought the detroit was making noises. Took of the rear drive shaft and one of the u-joints was toast.

Gas Tank spring break trip?

[robertf03]

pillow block is that thing you have to draw in introductory cad classes

my f150 was a carrier bearing according to horeillys

[agjohn02]

pillow block is that thing you have to draw in introductory cad classes.

i guess they all do that, huh?

[robertf03]

yup