Tapping noise

[Craigcameron]

Hey Boiz I've got a 2010 st d40 Thai built I recently noticed
Tap sound every 30 or 40 seconds while idling sound like might
Be coming for gear box (maybe) not very mechanical minded!!!
I have a exceedy heavy duty clutch with single mass flywheel..
Just wondering if it something to worry about or just a normal
Thing that has just gone unnoticed until now.. Any help??

 

[Craigcameron]

It's actually more of a click sound since I lisend to it this morning.. Any help??

 

[Old.Tony]

Doesn't sound like a normal operational sound, when idling the engine is doing about 750 revs per minute and regardless of whether you're in gear (with the clutch in or out) or in neutral, there's nothing that I can think of on the car that would do that every 30 to 40 seconds. The fuel pump is cycling fuel back to the fuel tank at a fair pace but that's nearly constant - there are small fluctuations in fuel rail pressure (therefore small fluctuations in flow rate in the fuel return line) but these fluctuations happen several times per second.

Is your air conditioning on when this is happening? Does it go away when you turn the aircon fan off?

 

[Craigcameron]

Hey mate yeh I though it was the aircon but it's not running whilst the noise is there...

 

[Old.Tony]

I wonder then if it's the fuel breather on the tank. Can you narrow down the location of the sound a little more?

 

[Craigcameron]

Yeh to me sound like the gearbox? But it hard to say...