Crunch during cold start.

[jameshero]

Hey guys,

Car has been making this strange crunching noise intermittently during cold starts for a while now. Have mentioned it to the dealer several times when the car has been in for other warranty jobs, but each time they have 'failed to replicate the issue'. Attached is a link to the file, noise can be heard just after the 4 second mark. Any help would be appreciated as I would like to get this fixed before my warranty runs out in June.

Audio Link
Video Link

Cheers
James

UPDATE: Have taken a video of the revs dropping with the noise and uploaded it.

[Umai Naa!!]

Have you left it with them overnight?

[jameshero]

Have you left it with them overnight?

Yup. Was in for 2 nights specifically to find the noise. Then for 4 nights when I had my pressure plate replaced. Then again overnight when I had my timing chain tensioner replaced. Have mentioned it each time and each time they have said that they were unable to replicate the issue.

[Umai Naa!!]

Could be just coolant circulation in the heater core when the water pumps start up when the engine starts.

[vdubmotorworx]

That sounds weird.. have they hear your sound file?

[minke]

I guess, but I suspect it is clutch engagement of the AC compressor.

Why? With AC on and starting the car, the compressor is not engaged (to minimise load on the starter motor) then a few seconds in the compressor will be engaged. Well that's my logic.

Try the next few weeks ensuring the AC button is off before starting. Just to rule it out

[thewafflecaust]

Its the cam adjuster/positioner.

I believe this is the bulletin for it
TPI - 2009810/18 23.08.2010

[jameshero]

Thanks for trying to help out guys.

Could be just coolant circulation in the heater core when the water pumps start up when the engine starts.

Would the water pump make that noise? Anyway idea on how to prove/disprove this theory?

That sounds weird.. have they hear your sound file?

Yes they have. They acknowledged that there was a problem, but without hearing the noise in person they couldn't/wouldn't do anything.

Try the next few weeks ensuring the AC button is off before starting. Just to rule it out

Haven't switched my AC off since I got the car so will try it out and see if the noise disappears.

Its the cam adjuster/positioner.

I believe this is the bulletin for it
TPI - 2009810/18 23.08.2010

Anyway of proving it or getting the dealership to act on it?

[Umai Naa!!]

The pump itself doesn't make the noise, it's the coolant circulating in the heater core under the dash when you start the car.

[wai]

Is your foot on the brake or off?

The sound is too mechanical to be coolant or any other fluid.

Can you feel anything through the gear lever?

Things that come to mind are the clutch throw our bearing.

Check the rpm at which the noise occurs. It sounds very much like a resonance thing. Something is spinning up and as it goes through this frequency it is vibrating internally or hitting something externally.

I had something similar with my Hiace. When I started it up for the first time in the morning, as it went through around 1000 rpm, there would be a horrible buzz that would go through the van. It turned out to be an exhaust clamp that had vibrated around just a few degrees to a point where with the exhaust cold, one of the clamp bolts would just make contact with the chassis rail. No point checking this when warm as the exhaust had expanded enough to move it clear of the chassis.

The solution was easy in my case.

Chances are that it is something like this (not necessarily the exhaust) in yours.

[thewafflecaust]

Anyway of proving it or getting the dealership to act on it?

I found that if i drove the car for a little, then left it off for 20-30 minutes and tried to start the car it would make the crunching/rattling noise 9/10 times.

I did this with the mechanic present and they sorted it out.

[mfl]

I found that if i drove the car for a little, then left it off for 20-30 minutes and tried to start the car it would make the crunching/rattling noise 9/10 times.

I did this with the mechanic present and they sorted it out.

and the cause was ?

[thewafflecaust]

and the cause was ?

See above or below..

Its the cam adjuster/positioner.

I believe this is the bulletin for it
TPI - 2009810/18 23.08.2010

[Maltopia]

I frequently got a crunching noise backing out of the driveway in the mornings. Realised after a while it was the fallen nuts from a palm tree near my driveway

[jameshero]

Hey Guys,

Thanks for the responses so far. After minke suggested that the AC engaging may be responsible, I've started switching the AC off before switching off the car. However yesterday morning the car made the noise again. Also noticed that the revs drop 100-200rpm for a second when the noise occurs, and then spring back up again, which would seem to be consistent with something engaging, however the AC was off so it can't be that. Might also be worth mentioning that the car sat for 2 weeks in January and the first time I started it up the noise was considerably louder than it had/has been before.

it's the coolant circulating in the heater core under the dash when you start the car.

This wouldn't cause a drop in revs would it?

Is your foot on the brake or off?

On

Can you feel anything through the gear lever?

Nup

Things that come to mind are the clutch throw our bearing.

Think the dealership may have replaced this before replacing my pressure plate in an attempt to stop a squeaking clutch. Noise was apparent before and after it was replaced though.

I found that if i drove the car for a little, then left it off for 20-30 minutes and tried to start the car it would make the crunching/rattling noise 9/10 times.

Have tried leaving it for 30 minutes a couple of times but it seems to only happen when the car has fully cooled down. Long enough that my car does that high idle thing to warm up. Would the cam adjuster cause a drop in revs?