Engine knocking - A4 B8 2011

[Christian27]

Hi, I have a A4 B8 2011 1.8 TFSI, and 3 months ago engine started to give a knocking noise, car has 148.000 km and it is regulary maintained.

Service history:
- Timming chains (upper and lower), chain tensioner and guides replaced at 145 000 km.
- Driver side coolant fan and controler replaced.
- PCV Valve was replaced at 146 000 km.
- Oil (5W-40) and filter changed just last month.
- Dealer replacer (1) piece hidraulic valve lifter? (not ) and give it back for testing, so far knocking continues.
- No codes on VCDS.


Knocking can be noticed at 0:14

Some advice what it could be?

[Allowencer]

Hard to tell from the video, but maybe the HPFP piston?

If not, I'd check valvetrain. If you had the timing chains replaced, do you know if the cam bridge screen was present or replaced? Was it reinstalled with a screen? I'd be worried about that primarily.

Another option, unplug the intake cam phaser and see if the noise continues. If it doesn't, it's not the intake cam phaser.

Another area, are the exhaust lobe pairs in the right position and the actuators working properly?

Need to narrow down the noise more.

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[Christian27]

Hard to tell from the video, but maybe the HPFP piston?

Im guessing the piston is part of the hpfp it self?, so you recommend swapping it?

Timming job was done by a dealer, so im not sure about the oil screen on the bridge, you think if i remove the bridge to check need to do re-time chains?

Forgot to mencion that knocking level sound goes down after driving for about 15 min, and you can hear it louder in when car is in cold start.

[Allowencer]

Im guessing the piston is part of the hpfp it self?, so you recommend swapping it?

Timming job was done by a dealer, so im not sure about the oil screen on the bridge, you think if i remove the bridge to check need to do re-time chains?

I'm tossing out ideas. It's truly hard to diagnose this way.

The piston rides on the exhaust camshaft and compresses the fuel pin inside the HPFP. If you remove the HPFP, you'll see the piston inside it and the vacuum pump.

If the dealer did it, more than likely they left the screen in or didn't even care about it. If the screen broke free, it can clog the lifter oil gally and that can cause lubrication issues on the valve train. I don't want to scare you, but it's plasuable.

You need to find where the noise is coming from.

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[SNice]

What allowencer said above - and another shot in the dark here. Your coolant looks not very good. It looks contaminated - with oil or rust. How is your oil level?


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[Christian27]

What allowencer said above - and another shot in the dark here. Your coolant looks not very good. It looks contaminated - with oil or rust. How is your oil level?


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Coolant was replaced back in july, they put in a dark blue stuff so i know its not contaminated or something.
As for oil, got some minor leak around oil cooler - Filter housing, im checking level every week thru MMI and refill when is need it.

[Christian27]

Well, after several days took it to a auto repair shop, and this is what we found so far:

1.- Screen oil on Cam bridge is gone, not sure it got removed by previous owner or may be stuck somewhere inside, what can i do about this?

2.- After removing cylinder head, 3 out of 4 cylinders are oily wet, thing is i'm not sure this is a symptom of the widely known oil comsuption issue on these engines, or something else, on attached pictures you can see both valves and pistons are oil wet, is this normal for oil burning? valves or pistons may be leaking oil?

Still looking for where the noise is coming from, mechanic suggested to replace all 16 lifters and rocker arms, but look fine to me.

Any advice or suggestions are appreciated.

[Allowencer]

1. Oil screen gone from the cam bridge - super common. Search and you'll find me, and the 5 other core people on this forum constantly talking about it and to NOT install one on rebuilds/fixes. It's pointless. You need to find all the pieces from it. Sometimes it's laying right there behind the cam bridge and against the head. Other times it's shredded and ventured down the lifter oil gally or even further. I've found pieces in the head and also in the oil pan before on engines. If the shop has everything, clean it all and DO NOT put in a new one.

2. Those are some extremely dirty pistons. Wow. It looks like a bunch of carbon build up with oil deposits. Either you have bad PCV and/or oil consumption issues too. Were you losing oil and had to add oil in-between oil changes?

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[Allowencer]

You can check each lifter by pushing on the seat once removed from the rocker and the oil meter plug is removed from the top of it. If the spring is collapsed or the seat sticks, they must be replaced. Frankly, they aren't that expensive and worth the piece of mind. I installed all new lifters on my personal latest build.

As for the rockers, as long as they are not physically damaged, the rollers spin fine without any catching and there's no backlash, the rockers are fine. Must be inspected though.

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[Christian27]

1. Oil screen gone from the cam bridge - super common. Search and you'll find me, and the 5 other core people on this forum constantly talking about it and to NOT install one on rebuilds/fixes. It's pointless. You need to find all the pieces from it. Sometimes it's laying right there behind the cam bridge and against the head. Other times it's shredded and ventured down the lifter oil gally or even further. I've found pieces in the head and also in the oil pan before on engines. If the shop has everything, clean it all and DO NOT put in a new one.

2. Those are some extremely dirty pistons. Wow. It looks like a bunch of carbon build up with oil deposits. Either you have bad PCV and/or oil consumption issues too. Were you losing oil and had to add oil in-between oil changes?

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Yeah had to refill 1 lt of oil for every 1000 km, but also had an active oil leak near oil cooler/filter housing area, checking that now as well.

[Christian27]

You can check each lifter by pushing on the seat once removed from the rocker and the oil meter plug is removed from the top of it. If the spring is collapsed or the seat sticks, they must be replaced. Frankly, they aren't that expensive and worth the piece of mind. I installed all new lifters on my personal latest build.

As for the rockers, as long as they are not physically damaged, the rollers spin fine without any catching and there's no backlash, the rockers are fine. Must be inspected though.

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Just bought all 16 lifters and replacing them tomorrow, i hope that solves the knocking issue, guess gonna leave rockers as they look good and spin as you pointed out, thanks for the help Allowencer!

[Allowencer]

Anytime!

Pro-tip, soak the lifters in some oil, can be SAE 30 or 5w-40 (room temp) over night. Allows the oil to get inside the lifter and eases startup for them.

I do this for any lifter on any engine build.

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[Audible4]

Did replacing the lifters solve your engine knocking problem? I have a knock on a motor that was sitting for 2 years and I swear it sounds like lifters

[Christian27]

Did replacing the lifters solve your engine knocking problem? I have a knock on a motor that was sitting for 2 years and I swear it sounds like lifters

Nah, had slap on 2 pistons so did replace all 4, got head machined, new valves, new oil pump ...

[Audible4]

Nah, had slap on 2 pistons so did replace all 4, got head machined, new valves, new oil pump ...

Did you have low compression? How did you determine this?

[Christian27]

Did you have low compression? How did you determine this?

No low compression, had to remove the head to check, since knocking continued after lifters were replaced.