1.9 AHU Knocking sound makes me crazy. Please help.

I posted here earlier regarding the same issue, but no solution has been found. Some people told me it could be rod knock, but i have driven 15000 km after that, and the sound is not getting worse. I even pulled a 1500kg trailer for 200kms with that poor 90hp engine without problem. The engine is running like normal.

IP, injectors and valve lifters have been replaced. The timing have been checked, double checked and triple checked.

Video of the sound:
https://www.youtube.com/watch?v=sdNFb9XU9Mg

My 99.5 jetta makes the same sound!! Any luck so far?

I keep a "mechanics stethoscope" in my toolbox to help isolate noises to a more specific area, it may take some practice to identify the noises that are supposed to be there, then you`ll hear the one that isn`t.

I just tightened down my ac clutch.. its a 14mm bolt in the center of the ac compressor, mine was loose tightened it down and no more noise.. just a thought.. I recommend everyone check theirs periodically..

Did you ever find out what the problem was?

AHU
yea that sounds about right.
forget about it and move on
my AHU is louder tap that that. its the "diesel"

First of all you should have been out at the engine when recording the sound, but from what I can here, it sounds like it could be a lifter. that is not a "knock" but it is a tapping sound. How many miles are on the engine?

DAM, just noticed its a 5 year old thread. i wish you noobs would PM the person rather than reviving a thread to just ask for the results.

Mongler98 said:

DAM, just noticed its a 5 year old thread. i wish you noobs would PM the person rather than reviving a thread to just ask for the results.

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I would much rather see the conclusion to a topic with final fix/results than all of the open ended ones that populate the TDI Club forums. Who cares if it is 5 years old?

If more of the unresolved issues had been updated with the "fix" lots of the "noobs" would be able to search these without having to post redundant questions for the same issue.

that would be awesome but most members do not make notifications for the threads they start. i seriously doubt this guy from Norway 5 years ago, who has not been active since 2015 will reply to his thread.
it takes a very small amount of work to see if the member who started the thread is still even active, let alone just a PM, to say, hey did you get a solution and can you post it?
Perfect world vs reality. PMing the person is a long shot but bringing up a thread that was dead 4 years ago is even more of a shot in the dark.
The best thing here is to try and contact him via youtube, seems thats just as hopeless based on comment history.

Mongler98 said:

that would be awesome but most members do not make notifications for the threads they start. i seriously doubt this guy from Norway 5 years ago, who has not been active since 2015 will reply to his thread.
it takes a very small amount of work to see if the member who started the thread is still even active, let alone just a PM, to say, hey did you get a solution and can you post it?
Perfect world vs reality. PMing the person is a long shot but bringing up a thread that was dead 4 years ago is even more of a shot in the dark.
The best thing here is to try and contact him via youtube, seems thats just as hopeless based on comment history.

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Well hello there Mr keybord warrior,
Thats some strong feelings you have......
But let me fill you in on some little facts,
I have had a similar fault with my own car and was researching common faults or maybe a not so common faults.
Ive thrown so much time effort and money trying to rectify my problem.
This guy seemed to have the same noise as me...
I messaged him in lots of different ways across different platforms, PMs and on threads like this.... still no answer.
Im sorry that by trying to get some advise its offended you.
Oh and i have been around a very long while now so im no 'noob'.

Sent from my SM-G965F using Tapatalk

you must be new here, check your emotions at the door bro. Your TDI is fine, this is how AHU's sound ALL THE TIME
How did i sound emotional? I have said nothing about how someone is or judging or name calling. you should do the same! Join date feb 2019?

The sound is due to worn out lifter bores, allowing oil pressure loss to the hydraulic lifters.

It is NOT "normal", but is unfortunately quite common with higher mileage early type TDI engines.

The fix is a new head, or if you have a machine shop that can do it, rebored and sleeved lifter bores.

Essentially, the lifters never pump up. Hence the ticking. It also slowly but surely beats the end of the valve stem to a tulip shape, and can in some cases get them so bad that they cannot be removed from the valve guides, even though the valve guides will also be quite worn, and need to be driven out with a punch... but both the guides and valves are junk anyway, so it isn't like you are hurting anything.

ALHs are a much improved design, unlike the AHU, were actually designed from the beginning with hydraulic lash adjusting followers in mind, not something added to the design mid life cycle. The AHU's design dates back to 1974, and hydraulics were added in the mid-80s.

i have a fully rebuilt head, sounds exactly the same as it did before and just like it does now. Its just every single AHU i have seen or driven sounds exactly like that. Well, now i know. 200K of driving like a wild turkey with that sound and a good bit of that with some decent power and the tops of the valves were fine and came out easy peasy but the side play of the guides was more than 1mm. So your saying that the cam i put in is not doing a darn thing if this tapping is present? SOAB!