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 wonder if the timing belt and other thing hitting a loose object. But then you have a loose object, you could hear it while driving.

Unlikely the engine itself, there are not many loose engine parts in there? :dunno: At least you cannot blame the valve like in the piston engine.

I would say get a good torch and look around, get someone to start the engine for you while you are looking.

I wonder if the timing belt and other thing hitting a loose object. But then you have a loose object, you could hear it while driving.

Unlikely the engine itself, there are not many loose engine parts in there? :dunno: At least you cannot blame the valve like in the piston engine.

I would say get a good torch and look around, get someone to start the engine for you while you are looking.

Each time it's happened, it's only made the sound once and at about the same time after startup. Sounds perfectly normal after that and while driving. I did have a good look around under the bonnet but couldn't see anything amiss.

is your aircon on when you start the car up?

Before I shutdown the car out of force of habit i turn off the aircon and radio.

I wonder if the timing belt and other thing hitting a loose object. But then you have a loose object, you could hear it while driving.

Unlikely the engine itself, there are not many loose engine parts in there? :dunno: At least you cannot blame the valve like in the piston engine.

I would say get a good torch and look around, get someone to start the engine for you while you are looking.

Well it's not the timing belt, of that I am 1000% certain. The Rotary engine does without such trivia.....:).

This sound occurs during start..........or just after the engine starts? A metallic sound? No stray tools under the hood? (other than the quizzical one looking for a strange sound ;) )

whats the ABS test?

Dave, I've been getting something like this too (occasionally on starting from cold) and I reckon azza's got the answer. See if it happens when a/c is left on, or off?
Will

whats the ABS test?

you may notice when you start your car and first take off, there is small clunk sound when you reach approx 6km/hr, or if you have your foot on the brake (steep driveway) then the brakes shudder slightly. only happens once on startup.

Whatever it is, it doesn't seem serious. If you want to track it down, you'll need to be under the bonnet while someone else starts it.

Good thing is, you're still under warranty. If it's a heat related issue it'll surface this summer. Now.......where's the champers? Oh, here it is......cheers!!

you may notice when you start your car and first take off, there is small clunk sound when you reach approx 6km/hr, or if you have your foot on the brake (steep driveway) then the brakes shudder slightly. only happens once on startup.

It will happen in reverse too, if that's the way you first travel after starting the car. About 6mph (10kph), according to the manual..... :) .

is your aircon on when you start the car up?

Before I shutdown the car out of force of habit i turn off the aircon and radio.

I can't remember if it's been on each time or not (it's happened about 3 times now).

I know the aircon is on atm and the car is outside in the sun all day today, so I'll see what happens when I start it up after sailing this evening.

Mind you, I've started the car plenty of times with aircon switched on previously and it's never made this sound before. As previously stated, it's not a minor mechanical sound. It's a quite audible thump and I've never heard it before, so I'm concerned something might be struggling and want to identify it before warranty expires (I've got a year to go though).

Well it's not the timing belt, of that I am 1000% certain. The Rotary engine does without such trivia.....:).

This sound occurs during start..........or just after the engine starts? A metallic sound? No stray tools under the hood? (other than the quizzical one looking for a strange sound ;) )

It's not during start. It's a second or so after the engine starts, which is usually when the A/C jumps into life (hence my suspicion as to an A/C related cause).

Doesn't sound metallic as such. More a graunching/thumping kind of sound.

No stray tools that I'm aware of. Mine's married. :angel:

I changed my oil cap after the Nationals (to a shiny Mazfix one :) ) but I can't see how that could be causing a noise. If it was, surely I'd be hearing it either once only or each time I start up.

Dave, I've been getting something like this too (occasionally on starting from cold) and I reckon azza's got the answer. See if it happens when a/c is left on, or off?
Will

Will do Will. :mdrmed:

Check for Possums....

I changed my oil cap after the Nationals (to a shiny Mazfix one :) ).

Mental note to self: Do not buy Dave a 710 cap for Kris Kringles if you get him :mdrmed:

Check for Possums....
LOL :cwm27:

Check for Possums....

I expect more constructive advice from my Melbourne co-driver :spank: .

I expect more constructive advice from my Melbourne co-driver :spank: .

Am I missing something??

I'd like to add my vote to an A/C-related noise. It could be a vapour lock in the system. I've heard that sound on some fridges we've had too.

The advice to turn off your A/C before switching off the ignition has merit. It does help to decrease the load on the battery when you start the car as well.

Dave

Misfiring starter motor not cranking up properly due to weak battery .

At least its not ticking :)............ (disgruntled client )

Am I missing something??

MACCAA said he might join me for the Victorian sojourn. Reckons driving for 10 hours each way to go on a one day cruise also suits his mentality :cwm27: .

Would that be okay with the Vics?

The advice to turn off your A/C before switching off the ignition has merit. It does help to decrease the load on the battery when you start the car as well.

Yes, that's sound advice but I don't always remember to do so.

And as posted previously, my concern is that this is a new phenomenon, and perhaps a harbinger of failure somewhere.

Dave

Misfiring starter motor not cranking up properly due to weak battery .

At least its not ticking :)............ (disgruntled client )

No Michael, the car is starting without a problem. I've had the starter motor, battery and plugs upgrade too.

As for disgruntled clients, never had one. :mdrmed:

It could be a vapour lock in the system.

I'm hoping it's something like this and is merely an isolated, occasional problem.

Guess I'll find out this evening.

MACCAA said he might join me for the Victorian sojourn. Reckons driving for 10 hours each way to go on a one day cruise also suits his mentality :cwm27: .

Would that be okay with the Vics?

Of course its fine. The more the merrier :angel:

Trust a NSWelshman to change things last minute :P joking!!!

Does this mean Maccaa be in the KK??

If it persists, you could consider a re-gas of your A/C and have the seals checked out.

Does this mean Maccaa be in the KK??

Not sure Kall. That's up to him. I have to check and see if he's still coming.

If he is and does join in the KK, I'm tipping Meguiar's waterless car wash products will be high on the probability list. :mdrmed:

Trust a NSWelshman to change things last minute :P joking!!!

What's last minute?! It's nearly a month away!!! :confused:

If it persists, you could consider a re-gas of your A/C and have the seals checked out.

Thanks Labby but if it persists Mazda can figure it out. I'll see how it goes over the next few weeks.

Not sure Kall. That's up to him. I have to check and see if he's still coming.

If he is and does join in the KK, I'm tipping Meguiar's waterless car wash products will be high on the probability list. :mdrmed:
If I had some i'd be happy to give them back ;)

What's last minute?! It's nearly a month away!!!
Should be done and dusted by now :bootyshak

What's last minute?! It's nearly a month away!!! :confused:


KK's need to be in advance to give people time.........

Us Victorians like to prepare way in advance :kiss:

ah! i ALWAYS wondered what that abs test was... i thought something was wrong with my car... the dealer should have told me about it

warm day today here. as a test I turned on the car, waited a minute then turned on the AC.

Outside temp was 27c degrees and the climate control was set to 24c. There was an audible clunk as the aircon compressor fired up. Funny how I was used to hearing it and thinking nothing of it. Just tuned it out so to speak because I expect the AC to do it.

If I had some i'd be happy to give them back ;)

Really? I thought it worked pretty well. Not saying I'd like to use it all the time but as a quick spruce up it did the job for me.

KK's need to be in advance to give people time.........

Us Victorians like to prepare way in advance :kiss:

In Sydney we're usually still begging people to come at this stage. :rolleyes: ;)

warm day today here. as a test I turned on the car, waited a minute then turned on the AC.

Outside temp was 27c degrees and the climate control was set to 24c. There was an audible clunk as the aircon compressor fired up. Funny how I was used to hearing it and thinking nothing of it. Just tuned it out so to speak because I expect the AC to do it.

Yep, I'm starting to think that's all it is too.

When I started the car up yesterday I still had the A/C on and it made the same kind of noise. I'm going to try again on Wednesday with it off and see what happens.

It may be that the more extreme heat caused by leaving it in the sun all day causes the compressor to be activated with greater force, thus making a more audible 'clunk' (good word - that's what it sounds like). Still, I've parked the car in the sun previously and not noticed it as much :dunno: .