Thread: 300TDi knock noise

Maybe stitch it back together
Drop the timing back to 1.5mm of lift
You’ll lose a little bite but if the noise changes at least you’ll know it is just knock ?

I’m super frustrated for you mate
I too would be chasing that noise down!

S

Originally Posted by rick130

Other than the oil pressure collapsing at idle, I found big end noise only really noticeable on the overrun at high revs in aTdi?

I guess that depends. A knocking big end is very serious in ANY engine AFAIK. The more it knocks the worse it gets. Once the bearing loses the oil wedge then it's only a matter of time, unless 300 TDis have some sort of secret armour.

Originally Posted by johntins

I guess that depends. A knocking big end is very serious in ANY engine AFAIK. The more it knocks the worse it gets. Once the bearing loses the oil wedge then it's only a matter of time, unless 300 TDis have some sort of secret armour.

So a big end can knock and the engine can still have good oil pressure?

Originally Posted by roverrescue

Sounds to me a bit vacuum pump - the world won’t end if you pop the pump off, jam a bit of cardboard against the holes and run at idle

If no change is check your tappets- not quite right pitch for tappet strike buts it’s quick and easy to cross off

Then I would Check the IP lift at TDC (timing)
A 300tdi with too much advance gets a sharp knock like that at idle

I would be surprised if those three don’t pull it up

S

*Yep, sounds like the vacuum pump to me, but its not bad.

answer to other replies:
*Trouble is you can replace the vacuum pump and the new one can have the same sound.
*Yes it will still have vacuum.
*Overall sounds pretty ok for a 300tdi

Originally Posted by roverrescue

Maybe stitch it back together
Drop the timing back to 1.5mm of lift
You’ll lose a little bite but if the noise changes at least you’ll know it is just knock ?

I’m super frustrated for you mate
I too would be chasing that noise down!

S

Good tip. I retarded the IP as far as it would go on the pulley and the engine ran like crap but the knock was still there. So i guess it's not knock due to the IP timing...
All the injectors are new too.
I guess it could be rod knock/tap but i'm 100% certain all nuts were done up to torque and then double checked! So, if it was rod knock something strange must have happened...

Originally Posted by johntins

I guess that depends. A knocking big end is very serious in ANY engine AFAIK. The more it knocks the worse it gets. Once the bearing loses the oil wedge then it's only a matter of time, unless 300 TDis have some sort of secret armour.

John, I'm not saying a big end knock is not a problem, its a huge problem, I'm just saying IME it's not that noticeable, at least initially, in a Tdi.

Ever since i replaced head on mine had pretty much same sound. That was few years ago and few k kms. Engine still runs well.

I assume it was since i changed head. Might have been there even before but don’t remember noticing. Was actually someone here that picked it up on a video i posted it which alerted me to it.

When i was doing tappets one of rods wasn’t seated properly and it went with a loud pop as i turned engine. Had me paranoid that I’d done damage to follower. Another issue i have is on start up the idle always seems to struggle like a valve is stuck or something. Happens for a few seconds.

I learned to live with it. One theory i had was possible issue with the amc heads. Other theory (more plausible) is i did something wrong. But as mentioned, runs well and never given me problems. Touch wood.

Originally Posted by Fausto79

Ever since i replaced head on mine had pretty much same sound. That was few years ago and few k kms. Engine still runs well.

I assume it was since i changed head. Might have been there even before but don’t remember noticing. Was actually someone here that picked it up on a video i posted it which alerted me to it.

When i was doing tappets one of rods wasn’t seated properly and it went with a loud pop as i turned engine. Had me paranoid that I’d done damage to follower. Another issue i have is on start up the idle always seems to struggle like a valve is stuck or something. Happens for a few seconds.

I learned to live with it. One theory i had was possible issue with the amc heads. Other theory (more plausible) is i did something wrong. But as mentioned, runs well and never given me problems. Touch wood.

Interesting... I've been trying to think how a damaged follower could make that clack/knock noise though? After all, if the the valve clearances are still good after running the engine wouldn't that mean that the follower assembly has no excessive play in it?