Crank Squeal?

[tjcdigital]

I've a persistent, high pitch squeal coming off the timing chain side of my 1.0 '99 yaris, its got 120k on the clock.

we've isolated the noise to the internals (not a loose aux belt/alternator/water pump/idler prob).

It squeals loudly and consistent when the aux belt is fitted and its idling, but cuts out when i drive in motion.

with the aux belt off, the squeal doesnt happen, unless i rev the accelerator. then its just slightly apparent in the rev range between 1-2k rpm, for like 1 second then cuts out. So the aux belt makes it worse, and the noise disappears with the belt on or off over 2k rpm, but its definately coming from an internal part.

all i can think of:-

crankshaft bearing?

vvti controller unit?

camshaft problem?

exhaust sprocket?

any light shed on this would be grateful received.

[HowardL]

I bet it is the belt, slipping ever so slightly

[tjcdigital]

I bet it is the belt, slipping ever so slightly

its not, because it happens when the aux belt is off completely. its just not as pronounced.

[carlowlad]

thats a bit of a worry. I was thinking along the lines of a water pump or alternator bearing but since you say it does it with the belt off then it's not likely to be those. Is your water pump driven by the timing belt or by the aux belt like the d4d? If it's driven by the timing belt then there's a chance it may be that.

Other than that i'd check the oil for level and quality. If it's low, top it up. If it's due a service, do it. But use engine flush before you change the oil. There may be a crank bearing not getting enough oil due to sludge build up.

Sorry i cant be more helpful. Good luck with your troubleshooting!

Edit: I reread your post and noticed you have a timing chain. Doh! Well then, it's starting to sound like a crankshaft bearing but i'm guessing they'd die quickly with that kind of sound coming out of them. Hmmm.....stumped!

[tjcdigital]

thats a bit of a worry. I was thinking along the lines of a water pump or alternator bearing but since you say it does it with the belt off then it's not likely to be those. Is your water pump driven by the timing belt or by the aux belt like the d4d? If it's driven by the timing belt then there's a chance it may be that.

Other than that i'd check the oil for level and quality. If it's low, top it up. If it's due a service, do it. But use engine flush before you change the oil. There may be a crank bearing not getting enough oil due to sludge build up.

Sorry i cant be more helpful. Good luck with your troubleshooting!

Edit: I reread your post and noticed you have a timing chain. Doh! Well then, it's starting to sound like a crankshaft bearing but i'm guessing they'd die quickly with that kind of sound coming out of them. Hmmm.....stumped!

cheers carlowlad, yeah bit of a worry i cant quite pinpoint it. its definately an internal noise, coming off a bearing part inside and all i can think of is crankshaft bearing.

[Madasafish]

So the aux belt makes it worse, and the noise disappears with the belt on or off over 2k rpm, but its definately coming from an internal part.

That suggests the item giving the noise is the front crankshaft bearing or seal. With the belt there will be additional tension and hence the increased noise.You could have a seal which is disintegrating . I understand seal removal and refitting may be an engine out job but Haynes is a bit vague.

[tjcdigital]

So the aux belt makes it worse, and the noise disappears with the belt on or off over 2k rpm, but its definately coming from an internal part.

That suggests the item giving the noise is the front crankshaft bearing or seal. With the belt there will be additional tension and hence the increased noise.You could have a seal which is disintegrating . I understand seal removal and refitting may be an engine out job but Haynes is a bit vague.

thanks madasafish, funnily enough i've just replaced the crankshaft oil seal, it had been seeping on closer inspection for a while, and we thought that would kill off the squeal too.

so although we've replaced the crank seal, it still squeals, leaving me to believe its a crankshaft bearing.

NB:- anyone else who needs to do a crankshaft oil seal, its quite simple. just whip off the mount and support and drop the engine with a trolley jack and you've plenty of access to fiddle around. haynes do describe it as a engine out job, but it aint.

[goodison]

Have you checked the crank pulley, its a bonded anti-vibration pulley. Meaning it is two metal portions that are bonded together with a rubber insert, check that the rubber hasn't split off one of the pulley surfaces allowing it to not spin at engine speed. Loading it with the alternator belt tension will make it worse. Remove the pulley and see if you can push the two pieces apart

[tjcdigital]

Have you checked the crank pulley, its a bonded anti-vibration pulley. Meaning it is two metal portions that are bonded together with a rubber insert, check that the rubber hasn't split off one of the pulley surfaces allowing it to not spin at engine speed. Loading it with the alternator belt tension will make it worse. Remove the pulley and see if you can push the two pieces apart

cheers goodison, ill give it a look

[tjcdigital]

UPDATE:-

if anyone is following this present or future,

i bought a stethoscope and traced the squeal back to the inlet manifold (yes i know, along way from the crank), assuming its a knackered o-ring in the throttle body.

going to take a better look on the weekend.

see if i can finish it this weekend/early next week, depending on parts, so will post up if i manage to kill it off.