Engine noise - Top end knocking/tapping, gases coming from oil filler.

T5 Byron

New Member
T5.1 2.0 TDI 100k CAAB

We only use the van for trips, and I've noticed a tapping noise that's got gradually worse over the last few months.

On checking under the he bonnet to try and locate the sound I opened the oil cap, and it was immediately clearer/louder.


There also what looks like exhaust gases, pumping out in time with the noise.

Other than the noise, there's no other indicator that something is wrong.

No warning lights or fault codes on VCDS.
Drivers well, no loss of power.

Just done two engine flushes, it's running fresh oil, and is regularly serviced.

So far, the shortlist of potential problems is:

- Damaged Camshaft, followers, lobes
- Sticky Lifters
- EGR valve stuck open

Appreciate any help narrowing down the cause. Will probably get it booked into VW for a diagnosis next week. Thanks
 
Some blow-by is normal, however that does look excessive.
You don’t mention the oil consumption rate?
You can get an idea of engine wear by completing an oil analysis, make sure the data entered is 100% correct. You’ll need a small syringe and some flexible tubing to fit down the dipstick tube to draw off the oil, easier done when warm.
 
@DXX Thanks for the fast reply!

Oil consumption rate – I've got no analysis/calculations if that's what you mean (can you find this in VCDS?) but since owning it, and putting 4k miles on it, the oil hasn't needed topping up.

It's had two oil changes during those 4k miles, one of which was this weekend in an attempt to tackle the noise.

The Vision oil test looks worthwhile, especially on a high-mileage vehicle. I'm guessing I need to put a few more miles on this fresh oil before extracting some for the test. I've got the old oil which contains some Liqui Moly engine flush – I guess that would skew the results.

Van is booked in with the nearest VW commercial garage this Friday, so hopefully, they'll be able to narrow things down.
 
can you find this in VCDS?)
No
I'm guessing I need to put a few more miles on this fresh oil before extracting some for the test.
Yes
I've got the old oil which contains some Liqui Moly engine flush – I guess that would skew the results.
Probably, also the oil sample needs to be uncontaminated as the analysis is looking at very small particles and quantities (PPM), oil drained into a bowl etc won’t be uncontaminated, hence the syringe and tube.
 
@DXX Thanks for the fast reply!

Oil consumption rate – I've got no analysis/calculations if that's what you mean (can you find this in VCDS?) but since owning it, and putting 4k miles on it, the oil hasn't needed topping up.

It's had two oil changes during those 4k miles, one of which was this weekend in an attempt to tackle the noise.

The Vision oil test looks worthwhile, especially on a high-mileage vehicle. I'm guessing I need to put a few more miles on this fresh oil before extracting some for the test. I've got the old oil which contains some Liqui Moly engine flush – I guess that would skew the results.

Van is booked in with the nearest VW commercial garage this Friday, so hopefully, they'll be able to narrow things down.
Hi, new to the forum, did you find out what the problem was as I'm experiencing the same with my T6
 
Hi, new to the forum, did you find out what the problem was as I'm experiencing the same with my T6
It's approaching a year since I first noticed the issue, and it's still there although not as noticeable.

I've done about 4,000 miles since without any mechanical issues.

Last month I sent off an oil sample (like @DXX recommended) to Darkside Developments and it came back with a full bill of health (no sign of wear), so much so that they asked why I was testing it.

I explained this issue and they said that it could be EGR related - if stuck it might be send too much exhaust gas into the crank case.

So that will be my next thing to look into when I get the time and money.
 
It's approaching a year since I first noticed the issue, and it's still there although not as noticeable.

I've done about 4,000 miles since without any mechanical issues.

Last month I sent off an oil sample (like @DXX recommended) to Darkside Developments and it came back with a full bill of health (no sign of wear), so much so that they asked why I was testing it.

I explained this issue and they said that it could be EGR related - if stuck it might be send too much exhaust gas into the crank case.

So that will be my next thing to look into when I get the time and money.
It is safe to say if the EGR has 100K miles it is junk. It’s a false economy to avoid renewing it as the soot contamination of the induction system, engine oil and DPF will eventually be more expensive.
 
Did a little more digging into this. Checked the EGR valve and noticed the OEM unit has been replaced with a Valeo one. Searched through the paperwork from previous owner, and found a receipt for some VW Dealer work to replace the EGR. It was done in May 2018 at 60k miles, so I assume it was warranty work.

So that means the EGR has about 40k miles on it – probably starting to get coked up, and after looking at all the videos, i'm tempted to whip it off and check the condition, and if it's not too bad, might be able to clean it up and get some extra miles on it.
 
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