club.liberty.asn.au

Hey all,

When I accelerate quickly from standstill, there is a loud knocking sound coming from the engine and lasts about 3-5 seconds.

Has anyone had this happen in the past and possibly know the cause?

Oil was fine (correct level) and I did a service on it last week using Mobil 5-30w include the upper engine cleaner.

What do you mean 'lasts'? do you have a video?

best case.. something has broken that isn't the bottom end .. worst case your bottom end is now garbage, say hello to a $6k+ engine replacement/rebuild.

NDARYD wrote:Hey all,

When I accelerate quickly from standstill, there is a loud knocking sound coming from the engine and lasts about 3-5 seconds.

Has anyone had this happen in the past and possibly know the cause?

Oil was fine (correct level) and I did a service on it last week using Mobil 5-30w include the upper engine cleaner.

Did this start happening just after your sydney drags? ..

Check for abvious things....maybe check your exhaust? dump? mounts? a video clip would help...

Probably blown CV joint from the drags last night.

Does it make the sound when you rev it in neutral?

Haha not from the drags last night guys.

This problem has been there for quite some time but I haven't been able to locate the issue. I will make a video and then post it up, might be a bit easier to identify.

Doesn't make the noise when revved in neutral, only when taking off in drive. Not the CV either, I have replaced both the fronts recently and the noise was still evident. It seems like it is coming from the motor (internally maybe?) but it's hard to pin point as it doesn't occur in neutral so I can't have someone rev the engine while I'm looking around the engine bay - car must be driven.

Sure it's not detonation? Could be bad fuel...

NDARYD wrote:Haha not from the drags last night guys.

This problem has been there for quite some time but I haven't been able to locate the issue. I will make a video and then post it up, might be a bit easier to identify.

Doesn't make the noise when revved in neutral, only when taking off in drive. Not the CV either, I have replaced both the fronts recently and the noise was still evident. It seems like it is coming from the motor (internally maybe?) but it's hard to pin point as it doesn't occur in neutral so I can't have someone rev the engine while I'm looking around the engine bay - car must be driven.

Are you able to pull up a LV? or log the car? See if the car is picking up knock, pulling timing....etc...

I'm suprised you toke the car to the drags knowing of this issue prior....you are very brave and keen...

On initial start up, the 'knocking/rattling' sound will occur for about 1-2 seconds but doesn't happen every single time I start the car.

On harsh acceleration (off standstill only), the 'knocking/rattling' sound will occur for about 2-4 seconds - also doesn't happen every single time but majority.

Can it be a spark plug by any chance? I've changed 3 of the spark plugs about 12 months ago but the 4th spark plug (drivers side near firewall) I could not get out as the coil sleeve/bolt keeps spinning (btw any trick to getting it out considering it's so tight next to the chassis rail?)

Here is a video of the startup knocking which you can hear (from 2-4 seconds):

https://www.youtube.com/watch?v=_7N22yg ... e=youtu.be

Not sure how to pull up a LV or log.

No doubt about it - that's big end knock right there.

Your motor needs replacement. The bearing will grab eventually in the near future, and spit your rod out of your block

I've watched a lot of videos with big end knocks and they seem to be constantly there and not just for a few seconds like mine? If I drive it sensibly (not taking off higher than around 4-5,000rpm) it won't make any noise.

Do you think it' still the big end knock?

Main bearing knock is constant

Big end knock only under load or startup

It will gradually get louder under load

I'm willing to say with a high degree of certainty from the sound that its big end rod knock

Thanks mate, appreciate the help

Time to think about where I go from here haha.

Could also be pinging its head off from AVCS Cam gear blocked and static.

NDARYD wrote:On initial start up, the 'knocking/rattling' sound will occur for about 1-2 seconds but doesn't happen every single time I start the car.

On harsh acceleration (off standstill only), the 'knocking/rattling' sound will occur for about 2-4 seconds - also doesn't happen every single time but majority.

Can it be a spark plug by any chance? I've changed 3 of the spark plugs about 12 months ago but the 4th spark plug (drivers side near firewall) I could not get out as the coil sleeve/bolt keeps spinning (btw any trick to getting it out considering it's so tight next to the chassis rail?)

Here is a video of the startup knocking which you can hear (from 2-4 seconds):

https://www.youtube.com/watch?v=_7N22yg ... e=youtu.be

Tensioner pulley?