Blanco
VIP Member
Starting the van from cold to move it on the driveway before packing for a week away and the engine let out a massive shriek. After a few seconds the noise quietened down and everything seemed to run as normal. However, every time the engine started there was a momentary loud squeak. Sounded like the sudden escape of pressure from something.
Suspicion fell on the auxiliary belt tensioner having failed although investigation indicated nothing wrong. BUT the centre section of the crankshaft pulley that drives the auxiliary belt could oddly be rotated within the pulley itself by about 1.5cm in either direction, which I’m told really isn’t meant to happen.
On T6’s the centre of the pulley carrying the auxiliary belt is apparently bonded to the outer part with a rubber anti-vibration cushion (I’m sure there’s a proper way of describing this) and it seems the two can decide to part company all of a sudden. When it occurs and the engine starts the outer pulley attached to the crankshaft rotates until it takes up the slack in the cushion at which point the auxiliary belt engages with sufficient jolt to stretch it before the tensioner spring reacts and almost throws the belt off the tensioner wheel causing the squealing. The sound of pressure escaping presumably is trapped air in the void worn inside cushion being forced out.
This was less than 40 miles after the auxiliary belt had been replaced at 56k miles. The original VW belt taken off was 1555mm long, and the replacement 1548mm. VW had once I’m told realised the longer belt was too long for the tensioner and shortened it 7mm. I’m thinking the shorter belt put extra pressure on an already partly worn cushion causing it to fail.
Does this sound broadly familiar to anyone?
New pulley then. Rather more expensive unfortunately than a tensioner … £570 plus bolts. Ouch. At least it happened at home and not the middle of Wales halfway through our trip. Every cloud as they say has a silver lining. Me just trying to remain positive!
Suspicion fell on the auxiliary belt tensioner having failed although investigation indicated nothing wrong. BUT the centre section of the crankshaft pulley that drives the auxiliary belt could oddly be rotated within the pulley itself by about 1.5cm in either direction, which I’m told really isn’t meant to happen.
On T6’s the centre of the pulley carrying the auxiliary belt is apparently bonded to the outer part with a rubber anti-vibration cushion (I’m sure there’s a proper way of describing this) and it seems the two can decide to part company all of a sudden. When it occurs and the engine starts the outer pulley attached to the crankshaft rotates until it takes up the slack in the cushion at which point the auxiliary belt engages with sufficient jolt to stretch it before the tensioner spring reacts and almost throws the belt off the tensioner wheel causing the squealing. The sound of pressure escaping presumably is trapped air in the void worn inside cushion being forced out.
This was less than 40 miles after the auxiliary belt had been replaced at 56k miles. The original VW belt taken off was 1555mm long, and the replacement 1548mm. VW had once I’m told realised the longer belt was too long for the tensioner and shortened it 7mm. I’m thinking the shorter belt put extra pressure on an already partly worn cushion causing it to fail.
Does this sound broadly familiar to anyone?
New pulley then. Rather more expensive unfortunately than a tensioner … £570 plus bolts. Ouch. At least it happened at home and not the middle of Wales halfway through our trip. Every cloud as they say has a silver lining. Me just trying to remain positive!
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