Loose Idler pulley nut.

[gumball]

I had a nasty shock when I got home from Brands-Hatch(great racing btw), when parked I could hear some nasty noises from the engine bay, so when I had a look under the engine cover I saw that the idler pulley was cocked at an angle and rubbing on the bracket (making squealing noise). Somehow the nut had come loose!
I have tightened it up and now all seems well, would this have been touched during rocker-cover or sump pan removal? not looking for someone to blame, just a possible reason.

I was initially damning my exhaust for drowning out the noise on the motorway*, but I guess it saved me the worry all the way home, as it has turned out OK.(so far). :)

*She sounded fantastic launching out of the Dartford toll :proud:

[Kaz-kzukNA1]

Hi, gumball.

I guess you are referring to the locking nut located at the side of the cover plate of the A/C belt idler pulley.


If that is the case, then, very unlikely to be touched during the process you mentioned.

Having said this, if you have an aftermarket header or NA2 OEM header, depending on the design, you may have to loosen the front header in order to remove the sump pan off the engine.

During this process, the A/C compressor may have been shifted from the bracket and as mentioned below, the tension adjuter may have been touched.


Unless the engine is tilted, it is extremely tight to attach standard socket and torque wrench to tighten the pulley nut.


I normally use crow’s foot on the torque wrench if the engine was not tilted.


Obviously, you will loosen the nut when removing/replacing the A/C belt.


Other than the obvious case such as TB service, A/C refresh, etc, there are several occasions when you have to remove the A/C belt.


One example is the header installation.

You will very likely to remove the A/C compressor and although you don’t need to touch the belt tension adjuster, some people may loosen it first before removing the compressor.


Hope you managed to catch the symptom early enough and no side effect to the surrounding area.

Kaz

[gumball]

The engine sounded fine when I left the event so worked loose on the 50 ish miles on the way home.
Not the tensioner bolt but the main one through the centre of the bearing, maybe due to a bearing vibration?

Nut 21 on the diagram below:
http://i190.photobucket.com/albums/z148/gumball3ooo/a-c-compressor-1-223478.png