M32 Gearbox + Clutch: Pics and Analysis
My Alfa 159 TBi 2012 and 70,000 miles was not happy, it may help some of you if I go through its recent repair.
Symptoms: A 'hiss', clearly not a normal sound, louder on the left of the car and which got louder the faster you drove and the higher the gear - they are connected of course but the hiss could just be heard in third and was quite audible in 6th.
The pitch of the hiss was related to road speed only, the gear you were in was irrelevant, so this suggests something with a fixed connection to the wheels.
The sound of the hiss (not the pitch) could be changed by rocking/holding the gear stick from side to side. I checked and this lifts the gear selector slighty even though it is a cable connection.
Unrelated, and not considered because it is my first 159, was that the change up from first to second was 'slow' and the car seemed to labour when it got into second - my 156 zipped between all gears without missing a beat. The gear selection was hard at times and each gear seemed to have a different degree of difficulty.
OK, so into a garage specialising in Alfas and after four days in the garage and a bill of £1980 (including VAT). It had the gearbox stripped down and all bearings and seals changed, over filled with Sintofluid, the subframe cleaned and given rust protection, tracking realigned, a new dual mass flywheel, new clutch plate, new concentric slave cylinder and two new suspension bushes.
I got the man to keep the parts so I could see what was happening. The clutch plate was quite thin, the flywheel plate could be rocked by about 10mm and rotated by about 20 degrees. One suspension bush was clearly failing.
I will try to attach pictures of the bearing surfaces which do have damage (but I am no bearing expert) - none of them had failed drastically, but all of them feel 'crunchy' when rotated. Oddly one of then seems to sit high in its 'cup'. I suspect that wear damage to all of the bearing surfaces probably comes from never having the oil changed.
Going for a test drive, and great, no hiss, the clutch action is smooth as silk, first to second is how my 156 used to be and changing gear was much easier in all gears and they all felt the same. Accelerating from first used to threaten to stall and pulling away from second on roundabouts the car used to fade rather than accelerate. Both effects now gone!
The new suspension bushes eliminated the embarrassing squeak when driving down my street!
I hope you find that useful.