Engine whine

[Slartibartfast]

Last fall, my dad and I swapped out the accessory belts in my Pathy, and apparently left one a little too loose. It started squealing at startup and under acceleration. By the time we got around to tightening it, the squeal turned into a constant sort of whine. Even with the belts tight, something was still squealing. Pretty much since then, it's whined whenever I'm close to 2k RPM. No missing, no loss of power, no CEL, no weird sounds at any other speed, just this sort of warbling whine (not very loud, and not grinding or whistling). I've taken all the accessory belts off, and it still whines, so it's not the alternator, water pump, power steering pump, fan clutch, air conditioner compressor, or idler. It doesn't care what gear I'm in or how hard I'm pushing it or anything.

 

Last fall, I had the oil changed at an iffy-lube sort of place, and it turns out that they overfilled it a bit. It's higher than the little crosshatch bit at the end of the dipstick, but I'm not sure by how much... hard to read on the cable part. It's leaking all over the front diff and crossmember, but it's been doing that since we got it. My dad and I think it's the pan seal, and aren't terribly worried about it. We suspect that this is coincidental to the noise, but on the off chance, there it is.

 

I suspect that the harmonic balancer (which is built into the crank pulley, right?) went bad when the belts were acting up, but my dad says the noise doesn't sound like a balancer to him. He thinks there's something wrong with the mechanism driving the distributor (which looks new and feels fine). The timing belt was done 1-2k ago (165k overall).

 

We're at a loss, so rather than replace things and hope, we're taking it in on Friday. I'd still like to figure out what's making the noise, if only to shut it up until then. Any ideas?

 

Thanks for reading.

[adamzan]

Did you put the timing belt on too tight? I know it can make a nasty whining noise.

[Kingman]

The distributor runs off a gear on the camshaft, there's no way for anything in there to whine. Too tight of a timing belt sounds about right, was it tensioned properly? 1/2" deflection at 22LBS? You could pop off the crank pulley and start it to see if it's that.

[Slartibartfast]

I don't know, we had a mechanic do it when we got the truck. It ran quietly (well, except for the usual exhaust etc) for a year or more before the noise started. Something to check, though.

 

Hmm... off to stare at the crank pulley to see if I can get a wrench on it...

Edited March 26, 2012 by Slartibartfast

[Tungsten]

I agree with the timing belt being too tight. If you removed all the belts and the noise was still there then it is the timing belt. Other than the timing belt being on too tight, it might also be the tensioner failing.

Edited March 26, 2012 by Tungsten

[Slartibartfast]

Brought it to the mechanic today, and he couldn't figure out where the sound was coming from either. Apparently the stethoscope doesn't work so well when the whole engine's vibrating. He thinks it's the timing belt tensioner, so he's tearing into that, and I'm driving a loaner. If it's the tensioner, he says he'll replace it under warranty (he did the timing belt). Since the noise only started recently, we've ruled out the belt itself.

 

Thanks for the input, guys, and I'll post again when I know more.

[Kingman]

Hope he checks the belt deflection against the FSM before replacing the tensioner instead of assuming it's fine.

Edited March 31, 2012 by Kingman

[nismothunder]

Timing belt for sure, or maybe even the cam seals leaking on to the belt causing bad things.

[Slartibartfast]

Turns out, though we had him do quite a few things to it, the T-belt didn't make the list because the PO said he'd done it already. Guess what? It's flogged out, and the tensioner is shot (good call, Tungsten). At least we caught it now, before it developed a taste for valves.