How to Fix VW Polo Idler Pulley Noise

Fix VW Polo Idler Pulley Noise

How to Fix VW Polo Idler Pulley Noise Using WD-40.

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Having a noisy idler pulley in your VW Polo can be concerning. I fixed this issue on my VW Polo 9N Mk4 with the 1.2L AZQ engine using a simple WD-40 spray.

The Noise Problem

If you’re hearing a metallic grinding noise rather than the usual belt squeal, it’s likely coming from your idler pulley. This is different from the typical squealing noise you might hear from a loose accessory belt. The noise is usually most noticeable when starting the car or during normal driving.

What You Need

  • WD-40 spray can
  • Safety glasses
  • Protective gloves
  • Good lighting (a flashlight helps)

Quick Fix Solution

How to temporarily solve the noise problem:

  1. Locate the idler pulley on your Polo’s engine
  2. Start the engine and listen carefully to confirm the noise source
  3. With caution, spray a small amount of WD-40 directly into the center of the idler pulley and NOT on the belt
  4. Let the engine run for a minute to work the WD-40 into the bearing
  5. Check if the noise has decreased or disappeared

Sprayed a bit of WD-40 on the idler pulley. The noise could be from the idler pulley or the belt tensioner pulley or the belt itself.

In my case the idler pulley or the belt was making the noise but I’m 99% sure it was the idler pulley.
I say that because at first if you look carefully in the video, I sprayed the pulley while the belt was running.

The noise was still there even though a bit of WD-40 went on the back of the belt. The noise sounded like a grinding metallic noise instead of a squeal – what an accessory belt noise usually sounds like.

The pulley in the video made this noise before. Again I used WD40 spray in the center to get it behind the pulley bolt cover and hope it will be fixed for at least a 1 year. Now there is no more noise.

Eventually the idler pulley needs to be replaced and to de-tension the accessory belt is a bit difficult because the torx slot for that can be damaged easily. I have a torx socket – the only way this can be done is with a proper torx socket.

Size is between T45 T50 or T55 I’m not sure now which one is it but if you need to pull back the tensioner pulley you MUST use the right tool or you won’t be able to take it out later.
Has to be a socket torx and the exact fit. Check until the tightest fit. I’ve got a socket torx set just for this and other difficult bolts.
Hope this helps you!

Video with louder idler pulley noise on engine startup and driving.

Safety

  • Never spray WD-40 on a hot engine
  • Keep your hands and loose clothing away from moving parts
  • Always wear safety glasses when working under the hood
  • If you’re not confident, have a professional mechanic repair it.

The Better Solution

While WD-40 can fix the noise temporarily (usually lasting about a few years), it’s not a permanent solution. Eventually, you’ll need to replace the idler pulley. Here’s what you should know:

  1. The proper repair requires removing the accessory belt
  2. You’ll need a specific Torx socket (T45, T50, or T55 – check for exact fit)
  3. Regular socket sets won’t work – you must use a proper Torx socket
  4. The tensioner bolt is soft and it can be easily damaged if using the wrong tool.

Repair Tips

If you decide to replace the pulley:

  • Buy a proper Torx socket set before starting
  • Test each socket size for the tightest fit before applying force
  • Consider having a professional do the replacement if you’re unsure
  • Always replace the belt when changing the pulley

How Long Will the WD-40 Fix Last

The WD-40 solution typically lasts about a year or a few year before the noise might return. When it does come back, you can either:

  • Apply the WD-40 treatment again
  • Replace the pulley
  • Have a professional mechanic check the entire belt system

Remember, while this WD-40 fix works well as a temporary solution, it’s not a permanent repair. If you start hearing unusual noises from your engine, it’s always best to have it checked by a mechanic.


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