Drive belt tensioner mounting bolt snapped twice

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DanUK
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Posts: 3
Joined: Sun Dec 06, 2015 5:48 pm
Drives: 02 1.9 sdi
Location: Brighton

Drive belt tensioner mounting bolt snapped twice

Post by DanUK »

Hello, I currently drive a very old, but beloved VW Polo 1.9l SDI with 150K. Its 2002, 9n, ASY engine model.

Back in November 2020 the battery light came on and the alternator had failed and needed replacing. I took it to a local garage who did this and replace the belt. A few days later the belt came off and the tensioner was loose within the housing it is normally situated in. I took the belt and tensioner out (It was just loose flopping around) and the bolt on the end of the tensioner itself (Which normally attaches it to the engine casing I believe) had snapped flush. I took it back to the garage who charged me a further £80 to replace this bolt and all had been fine for two months until yesterday. Out of the blue the battery light came on again. I checked under the Bonet and surprise, surprise, the tensioner is loose again, rattling in the casing, and the belt is off. I wiggled the tensioner out again, so it didn't fall off while driving back from the shop, and the bolt has snapped off again.

Has anyone experienced this problem and knows why it may be happening multiple times? Also, it appears the bolt was loctite'd in the second time.. I'm not sure how its coming out now ....


Here a link to a video I made the first time it broke. Its exactly the same now.

https://youtu.be/Qw6Pb9shDQw
RUM4MO
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Joined: Sat Dec 30, 2006 9:12 pm
Drives: B8 S4 & 6R/6C1 1.2TSI 110
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Re: Drive belt tensioner mounting bolt snapped twice

Post by RUM4MO »

First thing to check is the clutch or freewheel on the alternator pulley, next is, was that bolt torqued up to the correct torque value.
DanUK
New
Posts: 3
Joined: Sun Dec 06, 2015 5:48 pm
Drives: 02 1.9 sdi
Location: Brighton

Re: Drive belt tensioner mounting bolt snapped twice

Post by DanUK »

So it is a new alternator and apparently working fine and I have no clue what torque the garage used last time. Anyway, I took it back to the garage who weren't sure why it happened. They agreed to replace the bolt again and if that breaks a further time to replace both the bolt and the tensioner next time.The did that free of charge so I can't really complain.
RUM4MO
Bling Bling Diamond Member
Posts: 5859
Joined: Sat Dec 30, 2006 9:12 pm
Drives: B8 S4 & 6R/6C1 1.2TSI 110
Location: Mid Lothian

Re: Drive belt tensioner mounting bolt snapped twice

Post by RUM4MO »

Just one thing, was the alternator replaced along with its free-wheeling pulley, or was the old pulley swopped onto the new alternator.

For what it is worth, on the www.briskoda.net forum, Fabia Mk1 section, someone is having similar issues with a 1.9SDI though the tensioner body has been getting snapped!

https://www.briskoda.net/forums/topic/4 ... breakages/
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