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Aux belt tensioner(s) chattering	Please Register to enjoy additional Member Benefits

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TTron

Tue Oct 29 2024, 06:02pm

Member No: #31461

Joined: Jul 01 2013
Location: Portugal

About 6 months ago I bought a used but low mileage (~45K) 2016 C4 BlueHDi privately from a Polish chap who had an obsession with keeping it in tip-top condition.
Even my MOT inspector remarked on how good it is so, for the moment, it's a keeper.
It does have one niggle though which I would love to get to the bottom of and cure.
A couple of months ago I noticed a bit more noise than usual from the engine when idling and a quick look revealed the reason. The auxiliary belt tensioner was "chattering" away (roughly 20~30Hx but not consistent) and the pivot looked tired and rusty. So I guess it had been like this for a while, but you don't hear the noise from inside the car.
So I ordered a new 'kit' comprising BOTH tensioners and a new vee belt.
Fitting the kit didn't present any problems, I am quite used to getting my hands dirty and have tackled more demanding jobs in the past even though I am more accustomed to engineering on a much smaller scale.
To my immense disappointment, the problem persists. Granted, it's only at idle speed, but in Edinburgh traffic this can be quite a lot of the time and I'm sure if it's left like this I will be needing another tensioner before long.
I tried the old belt back on as it looks fine but still the same - no surprise there really.
What I did find though was if I spray the vee side of the belt with WD40 (engine running), the chattering immediately stops. Sadly it comes back after 30 seconds or so, but I feel this rules out any problems with the alternator or A/C pump. (And loading them doesn't make any difference). The bearings on both tensioner pulleys are lovely and smooth - the old ones were too.
So off with the belt again (fortunately I kept the wee pins that hold back the tensioners!!), I thoroughly cleaned all the vee pulleys and the belt, popped the belt back on and no chatter! For 30 seconds

then back it came.
And suggestion or help would be much appreciated, TIA.


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