I've noticed in the past couple of weeks a nasty, sudden graunching/thump kind of sound a second or so after the engine kicks over. It seems to be coming from the engine bay area. The car is still stationary when it occurs.

The weird thing is, it's not every time I start the car. My car is usually garaged but on Mondays and Wednesdays it's out in the sun all day. It's happened when starting the car up in the late afternoon on a couple of those days. The interior of the car is quite warm.

It's quite noticeable, to the point of exclaiming 'WTF was that?!' and getting out of my car and checking under the bonnet when it first occurred.

First thoughts are that it is the A/C compressor turning over. Should I get it checked and are there any other suggestions?

The car is otherwise running fine and I have no warning lights or other signs of a problem. The A/C appears to be running fine too. It is an '04 manual. I have had the starter motor, plugs and battery upgrade and the engine starts easily.

 

Sheesh, don't overwhelm me with responses guys. There's only so much I can take in at once.

 

Sorry Dude

I don't know WTF is that !!!!! But some guys there must know...

 

If you think it's the A/C compressor turning over then try starting the car without the A/C compressor engaged When you don't have the A/C turned on the compressor clutch disengages the compressor from the pulley.

 

Thanks Mike. I've since tried that and it does appear to isolate the problem.

Funny thing is, I've owned the car since 11/04 and regularly used to leave the A/C on and I've not previously noticed the sound of the compressor to be so sudden and loud - it's a perceptible thump - so I'm just concerned that it may be deteriorating in some way.

I'll get Mazda to look at it next time I'm in.