Is this a Camshaft/follower issue?

[WOKFM]

Hi,

2006 A4 1.9 PD engine.  170k miles (270k km).  

I thought it was developing a turbo/exhaust manifold leak, as it was making a real real BPuh Bpuh Bpuh Bpuh noise.   It was fine when I bought it about 5000 miles ago.  It's actually my daughters, so I don't drive it often, but I think it's developed over a couple of months, and maybe got worse over 1000 miles.  I don't often drive it, but it is only marginally down on power, but difficult to tell.   

Removed the airbox assembly, to get to the turbo and exhaust manifold and it's clear it's coming from the intake area (really loud when removing the Turbo I/C to inlet pipe).  The noise is very loud from the intake manifold.It did fail the MOT marginally on emissions, but on a second test a few days later (after I removed the EGR bypass plate that someone had fitted), it marginally passed - but that could be because the engine was cooler, and it was doing a different (FAST) test.

After a bit of research, a few people have indicated a worn  cam lobe, or follower, so today I took off the cam cover to have a look, and it's not really clear.  I think cam 6 and 8 look a bit tarnished, but that could have just been the oil, and i can't see the followers without removing the camshaft obviously.   I'm pretty sure the noise is towards the rear of the engine (IE by the fuel pump), but obviously it's hard to locate.   

I've done some videos and a slow-mo of it running.   TBH, most of the cam lobes look pretty clear, although 6 and 8 had a lot of oil splatter when running, so harder to see.

What do people think about this?  Does it sound like Cam/follower wear?  

 

 

 

 

 

Any thoughts on whether this is a safe bet to suspect such wear, in which case I'll order up a new camshaft and followers kit (and cambelt kit while I'm at it, obviously)

I realise that my videos don't really capture the essence of the noise that I can hear, because the camera has picked up the camshaft noise more than the intake noise.  But this video from someone else is exactly what I can hear - including the focus on the airbox.

I'd appreciate comments.

Edited January 28, 2023 by WOKFM

[Stevey Y]

5 hours ago, WOKFM said:

Hi,

2006 A4 1.9 PD engine.  170k miles (270k km).  

I thought it was developing a turbo/exhaust manifold leak, as it was making a real real BPuh Bpuh Bpuh Bpuh noise.   It was fine when I bought it about 5000 miles ago.  It's actually my daughters, so I don't drive it often, but I think it's developed over a couple of months, and maybe got worse over 1000 miles.  I don't often drive it, but it is only marginally down on power, but difficult to tell.   

Removed the airbox assembly, to get to the turbo and exhaust manifold and it's clear it's coming from the intake area (really loud when removing the Turbo I/C to inlet pipe).  The noise is very loud from the intake manifold.It did fail the MOT marginally on emissions, but on a second test a few days later (after I removed the EGR bypass plate that someone had fitted), it marginally passed - but that could be because the engine was cooler, and it was doing a different (FAST) test.

After a bit of research, a few people have indicated a worn  cam lobe, or follower, so today I took off the cam cover to have a look, and it's not really clear.  I think cam 6 and 8 look a bit tarnished, but that could have just been the oil, and i can't see the followers without removing the camshaft obviously.   I'm pretty sure the noise is towards the rear of the engine (IE by the fuel pump), but obviously it's hard to locate.   

I've done some videos and a slow-mo of it running.   TBH, most of the cam lobes look pretty clear, although 6 and 8 had a lot of oil splatter when running, so harder to see.

What do people think about this?  Does it sound like Cam/follower wear?  

 

 

 

 

 

Any thoughts on whether this is a safe bet to suspect such wear, in which case I'll order up a new camshaft and followers kit (and cambelt kit while I'm at it, obviously)

I realise that my videos don't really capture the essence of the noise that I can hear, because the camera has picked up the camshaft noise more than the intake noise.  But this video from someone else is exactly what I can hear - including the focus on the airbox.

I'd appreciate comments.

Hi as you say you can't tell from the the videos visually but the the noise rings bells and from the other clue about the emissions failure I would hazard an educated guess that one of the injector seals is blowing by, its a little copper seal that goes between the injector and the seating point in the cylinder head, had it on a couple of my Fords and the sound is familiar, if you follow the clues it points that way as if you were losing cylinder pressure the emissions go up as its not combusting the charge properly, a higher density of unburnt fuel through the exhaust.

Steve.

[WOKFM]

Hi.  Thanks for your comments.

I did consider whether it was injector related, but if there was a leak from there, resulting in cylinder compression blowing by, then i'd expect the noise to be very much focussed around the injector area itself, and I'd have expected to see oil spray around the seat when it was running.  But the noise is most definitely most audible within the inlet manifold (and then progressively reducing as you work back along the induction pathway - if you remove intercooler pipes it's really loud, and then it's very audible from the air box area.  This is why I think it's related to valve lift (or lack of).  But obviously can't be sure.