High pitched whine, only when accelerating (1 Viewer)

[slangdog]

Hi all

I've got a high pitched whine / whistle which starts at around 40mph. As soon as I lift my foot off the accelerator the noise stops - which makes me think (and hope like hell) it's not transmission related. I recently had the rear diff fixed and didn't like that bill one bit, but that was a constant whine.

Any idea's where to start?

Thanks.

 

[vasellers]

Just had this last week, same whine. Transmission clutches starving for fluid because filter clogged due to debris from torque converter (at least that's what the transmission guy told me). Then the transmission went out altogether, stopped truck, turned off engine, restart and trans would work for a while (junk falling out of filter while stopped.)

Flush and fill, change filter sounds like to me anyway.

 

[robustbambi]

Does the screeching ONLY occur when the AC is on? if so, its probably the AC belt.

 

[slangdog]

Thanks guys. Good question about the AC... thing is the truck is 24V and the AC is aftermarket (by PO). I unplugged all the 12V stuff that was connected directly to the 1st battery, and the AC is now not working. But I'm actually not sure where the AC pump is connected...

 

[cruiserman1]

maybe a belt?

 

[8960series]

Sounds like you might have a supercharger. Sorry couldn't resist.

 

[SPANNERSPINNER]

What transmission are you running?

 

[MT3000]

Slang dog,

I have the same issue. I had to put it up on a lift and engage in drive to replicate the sound. Mine turned out to be the tcase. I think it's a bearing in the tcase. So now it's time to rebuild.

 

[slangdog]

I've got the H55F gearbox.
MT3000, that doesn't sound great...

How hard is a tcase rebuild?

 

[MT3000]

I haven't done the rebuild yet. I've been researching and since the tcase has to be disassembled it may be more than I can handle. I don't have much mechanical know how and may have to find a mechanic to do the rebuild.

 

[slangdog]

Was chatting to a friend who has an older 2H, and funnily enough he said he has the infamous gearbox / transfercase oil leak, where the pressure pulls all the oil from the transfer case to the gearbox. He also experienced a whine.

I'm going to check my transfer case oil level this afternoon, hoping its not bearings and just a whine from running dry. In that case I believe running a hose from filler plug to filler plug equalises the pressure.

 

[aaron9252]

Reviving this thread, @slangdog , did you find this issue? My 2H is going the same, when I accelerate it sounds like a high pitch noise and I cannot figure out where it’s coming from. Faster speed makes it more apparent. Thanks

 

[g-man]

I had a quiet high pitched whistle coming from my t'case before I rebuilt it. It was just the idler bearings in the transfer case. Kind of a normal sound for an old land cruiser. Make sure your gear oil is full in the t/case and don't sweat it. Put your hand on the t/case shifter and see if you can feel vibrations that match the noise. Any real grinding or loud high pitched noise would be a concern.

 

[aaron9252]

This somewhat does the sound justice, any thoughts? No vibration at all, just the noise.

 

[OSS]

Reviving this thread

It sounds like worn differential gears to me. I've heard that sound before from worn diffs. To rule out if it's your tranny, accelerate in 4th gear (which isn't a gear, but actually direct drive). If it still makes a racket in 4th, then it's likely not the transmission.

Another way to pin point it is to remove the rear drive shaft temporarily and drive in 4H with the hubs locked. That will take the rear differential out of the equation. If the noise went away, the problem is in the rear axle.

If so, usually that sound is from worn gears caused by lack of lubrication some time in the past. The gear teeth contact surfaces wear more flat and make more noise. Usually it isn't a death sentence, just annoying as heck and the truck can still be driven another zillion miles.

 

[Idaho Savage]

I had a quiet high pitched whistle coming from my t'case before I rebuilt it. It was just the idler bearings in the transfer case. Kind of a normal sound for an old land cruiser. Make sure your gear oil is full in the t/case and don't sweat it. Put your hand on the t/case shifter and see if you can feel vibrations that match the noise. Any real grinding or loud high pitched noise would be a concern.

This... I have the same thing and I have a 4L60e.

 

[g-man]

But the OP's noise is not the t/case noise. I agree with OSS, most likely the diff. Check to see if you're leaking gear oil from your knuckles. See if it's dripping wet. As in dripping down onto the wheel and tire. Just greasy is kind of normal. But wet, dripping gear oil means the outer axle seals are leaking. This causes low gear oil in the diff. Also can be a dangerous condition and cause the brakes to fail if they are getting wet. Hopefully your noise will be diminished or go away some when you top off the gear oil in the diff.

 

[aaron9252]

@OSS what do you think of this movement? I removed the driveshaft and sure enough no more noise. I guess I’ll need a rebuild.

 

[brownbear]

aaron
I dont think that says much turning it. There is gear lash that is very normal. How much is hard to say, there may be something in the FSM.
The test on the output is side to side or up and down.
My TCase needs a rebuild. I get some gear whine too. Not quite as loud as yours but is sinilar. My t case for a long time pumped oil into the tranny and over filled it. Years a go I put in a hose. But it needs a rebuild.

 

[OSS]

That gear lash seems normalish but I don't know what the spec is.