Just wondering if someone on here is able to help me with the correct part.
I am still having squealing problems after replacing all belts and even a brand new crankshaft pulley.
My local Fiat specialist thinks it's "probably" the automatic tensioner that's causing the problem.

I have looked at the part numbers on the fiat eper but I see 2 tensioners (tighteners)
They call one a fixed tightener and the other an adjustable tightener.

However when searching for these parts they seem to both be called different things, so was just wondering if anybody could shed some light on what the correct part for me to order is? Which one is likely to cause the belt to squeal by not correctly adjusting the tension.

The 2 part numbers are:

Fixed Tightener: 7740252
Adjustable Tightener: 46750224

Thanks to anyone who can help

Either number 3 or number 5 on this image if it helps

The adjustable tensioner is the only one that adjust the belt tension.

When, and under what circumstances, do you get the squealing?
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Ah okay thanks.

When cold it squeaks really loudly for about 5 miles until warmed up. Seems to also do it when it's raining. Have done the old squirt water on the belt trick though and it stops instantly. Not really sure what else it could be apart from the tensioner now.

I've had a non - adjustable pulley (known as the idler pulley on many cars) go back in the states on the SAAB 9-3 we had at the time. From all I've seen, when they go they go. No gradual problems (unless the bearing inside starts to squeal or roar). Especially when they are crappy designs, like the one on the SAAB was (plastic grooved pulley heat attached...melted...to the inner bearing. Bearing survived plastic pulley shattered). Even if your adjustable pulley seems fine, it could be loosening out of tension a bit under load. Maybe watch it while some one puts a load on the alternator, cycles air conditioning etc

neonath said:

When cold it squeaks really loudly for about 5 miles until warmed up. Seems to also do it when it's raining. Have done the old squirt water on the belt trick though and it stops instantly. Not really sure what else it could be apart from the tensioner now.

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Squealing from the auxiliary drive belt for a short time after starting the engine can be caused by a faulty or failing battery. Starting an engine can drain the battery so much that the alternator has to work overtime to rechage it. This causes increased magnetism in the windings which can act as a brake on the alternator pulley causing the belt to slip and squeal.

Get the battery tested or replace it with a known good one to test.
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Davren said:

Squealing from the auxiliary drive belt for a short time after starting the engine can be caused by a faulty or failing battery. Starting an engine can drain the battery so much that the alternator has to work overtime to rechage it. This causes increased magnetism in the windings which can act as a brake on the alternator pulley causing the belt to slip and squeal.

Get the battery tested or replace it with a known good one to test.
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Click to expand...

I did wonder if the battery could cause any problems a while back so I had it checked about a month ago and it was fine so I kind of ruled it out.

However, since replacing my crank sensor as I was having starting problems and error messages, the squealing seems to have stopped?! Which I was certainly not expecting!

Could this be battery related after all like you say, as the faulty sensor was making the car turn over more times than normal to start and therefore draining the battery more. Now I have a new one it starts first time and it doesn't seem to squeal?! Not sure if this is possible or if it even makes sense but it kinda seems logical?