what is this thud?

[Silver-Aurion]

Every time on cold start, my car intermittently makes a thud noise like someone drops a brick on the engine and then the car violently lunges forward.

This is really really weird because it never used to do this and it's started doing it now for a few months, but never did this when I bought the car.

I have no clue what it is. Could it be the ABS check doing it while the car is still in park because the thud sounds exactly the same as the ABS check?

It's hard to explain because it happens within the first few seconds of started the car and it's not always. I realised also that it does it only when it's very cold outside. During warmer weathers where the engine will not be as cold it won't do this thud and lunge forward thing.

[Steven]

sounds like it could possibly be transmission related, if it isn't the ABS self-check (which, if you're in park and not moving, it shouldn't be)

[Silver-Aurion]

sounds like it could possibly be transmission related, if it isn't the ABS self-check (which, if you're in park and not moving, it shouldn't be)

Interesting. Never thought about it as being the transmission. But thinking about it a bit more it can be plausible. It's it tries to engage into gear but since it can't because everything is in park the car just lunges forward really weird like. The best way to explain it is like someone pushes the car forward and it snaps the car forward

I've booked the car in at the dealer for my dash rattle. So if I can also figure out what the hell this problem is I want to tell them to look at it. But at the moment I have no clue why it does it, what it is and how it happens.

[tekkyy]

besides the single sound (widely acceptable as ABS self check) once you reach 20km/h

I also get a bunch of fainter sounds around 40km/h

[Silver-Aurion]

besides the single sound (widely acceptable as ABS self check) once you reach 20km/h

I also get a bunch of fainter sounds around 40km/h

But I'm not even moving at all yet.

[blakepure86]

The first thing i would be checking is upper mount on lh side, When the oil feed recall was carried out The mount was most likely removed.

I have found one of the bolts worked itself loose and caused a knock

[Silver-Aurion]

The first thing i would be checking is upper mount on lh side, When the oil feed recall was carried out The mount was most likely removed.

I have found one of the bolts worked itself loose and caused a knock

Cheers mate, will have a look in the morning. I hope it's something that easy

[Silver-Aurion]

The first thing i would be checking is upper mount on lh side, When the oil feed recall was carried out The mount was most likely removed.

I have found one of the bolts worked itself loose and caused a knock

Cheers mate, will have a look in the morning. I hope it's something that easy

Well I had a look at all the bolts and they are tight as can be. Ever since the warmer weather there has been no thud.