Squeaky timing belt

I've just replaced the timing belt (proper Volvo one) and it squeaks for a few minutes before it warms up, then is silent. The old one didn't do this, nor did any of the previous 5 belts. The sprockets are clean, and the tensioner roller silent with no play, and I checked and rechecked that it was flat against the block. The belt clearly has a preferred track which is not quite in the centre of the three sprockets. I have tried gently easing it over half a milimetre, and rotating the engine by hand many times to check that it is still in position. But the moment I start up it moves back again. The belt is well clear of the edge of the sprockets, and seems in no danger of veering off. Can it be the case that after 380,000 miles the sprockets are very slightly worn, and this particular new belt is a tiny fraction wider than the old so partly runs on unworn metal? Does this matter? Will it settle down with a bit more running? (It has the later sine-wave profile teeth, and yes, the belt is the same!)

I haven't come across this problem before. Your theory sounds good to me - I can't see it causing a problem. maybe it will quieten down after running in for a while? Mike

Hi clifford...you"ve always been great with your advice when i post and i wish i could throw something into the think tank here..your description gives me the impression your on top of the job...the only thing that springs to mind is determine that it is the belt that is squeaking?...i have to be careful here not to say anything stupid like using a little water as a lube to see if this quietens the noise...well i"ve said it now...there goes what little reputation i had left!...regards hj.

i concur...cheers..hj.

What about the little disk that slides onto the sprocket before you put back on the crank pulley, is it there?? - Ive been caught out with this one before and it caused the belt to move.

Yes, it's there.

Just to report it has done 2000 miles now, and still squeaks for the first 10 minutes. After that it goes silent, but it reappears on restarting if the engine has cooled. I have inspected the belt, re-done the tensioner, but can't see anything amiss. So I am trying to tell myself it can't matter.

Seems daft but check the alternator belts are tight as this may be the problem.Slips just a little while the alternator works hard to put the starter voltage drop back into the battery I have never heard a cam belt squeak Richard

mine squeaked because the plastic shield over the timing belt faintly rubbed on the bottom pulley ,a squirt of wd behind the pulley stopped it for a few seconds. when i replaced the cam belt we found the top plastic cover hadent been bolted down correctly at the last change ,it stopped when the engine warmed up merely because the plastic must have bent slightly away from the pulley when warm and back when it cooled! you could see where over time the plastic had been rubbed away but not completely enough to cease the noise ,rust had also helped by pushing the covers metal cores over the bolt holes out slightly towards the engine .one gave a great problem removing it to clean it and put it back in the correct position ,probably the last guy had only done the bolt up tight but not tight enough to push the plastic against the engine ,the rust had formed behind the bolts head pushing the liner outwards a bit instead of flush with the plastic.