Losing 4L coolant in 10 days, no leaks – VW T6 2.0 TDI

S

sarahlein.hain@googlemail

Member
Hi all,

Looking for some advice (or shared pain!) with my 2016 T6 2.0 TDI Diesel (CAA A/B).

2023: EGR valve replaced after fault code. Since then, faint sweet smell from engine bay (coolant?) but no leaks found.

Later: Same EGR fault + coolant pump code → had both coolant pumps replaced. Van then ran fine for 6 months.

Hot day: coolant light came on, tank completely empty. Since then, it’s losing around 4L every 10 days.

No puddles, no pink residue, no oil contamination, just that sweet smell while driving.

Pressure test (20 min) showed no leaks. Coolant cap replaced. Still losing coolant.

Now the EGR fault code is back again.

Has anyone else had coolant vanishing like this with no visible leaks on the CAA engine?
Could it point to the EGR cooler? Or something that only shows when the engine is really hot?

Any ideas or similar experiences would be massively appreciated.

Thanks!
 
Id assume a radiator pinhole leak.

Or charge cooler leak.

The fact you can smell the sweet coolant is 100% proof that there is an external leak.

The leak must be steam when then system is under pressure.

The pressure test must have been inconclusive.

And you would expect to see some pink residue, but it may be under the engine or in the middle of the rad pack.

Slight possibility of a head gasket failure, but very unlikely from here.

****


I suppose I'd do a sniff test on the coolant for combustion gasses.

Re do a pressure test.

And get the engine hot after a 45min drive and get it on the ramps for a full visual inspection, including the rad pack.

You coudl possibly try bypassing the charge cooler water side for a sort duration. And inspect that for coolant ingestion.

The cooling system is very complex on these vans with high and low pressure sides, plus high and low temp sides, with multiple pumps and paths.

There will definitely be airlocks now,

There is a guided procedure to follow to properly purge the system of air, where by certain pump are run at certain times.
 
Thank you for your advise, I've got the van booked in for next week and will forward all this to the mechanic. He asked me to put it up here to see if anyone has had this problem before as well.
He said about doing a over night pressure test as well.
Thanks, I appreciate any help a lot!
 
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So...as promised I wanted to update you!, after a good look and search it turns out that my EGR was never fully replaced in 2023 (or at least that's what we are assuming that something went wrong there).
We fully replaced the EGR cooler valve again now and look at the photos of the old parts ...
What they have been looking like: (photo attached)
The lever on the EGR was fully seized.

There was definitely a leak and to top it off, the part that I allegedly had replaced in 2023 wasn't even put back into place with all the necessary screws at the time!
One screw was not installed at all!
I think I was scammed.
I had a feeling that the garage back then, wasn't really doing a good job.
At least I'm feeling I've got a helpful and trustworthy crew looking after the Van now.
Just had to move to Canada for that 😂 how ironic.
So far, no problems. I will take it for a long run in 2 weeks time and see if it stays that way!
Thanks for your help!!

PXL_20250912_233758802.webp
 
sarahlein.hain@googlemail said:
So...as promised I wanted to update you!, after a good look and search it turns out that my EGR was never fully replaced in 2023 (or at least that's what we are assuming that something went wrong there).
We fully replaced the EGR cooler valve again now and look at the photos of the old parts ...
What they have been looking like: (photo attached)
The lever on the EGR was fully seized.

There was definitely a leak and to top it off, the part that I allegedly had replaced in 2023 wasn't even put back into place with all the necessary screws at the time!
One screw was not installed at all!
I think I was scammed.
I had a feeling that the garage back then, wasn't really doing a good job.
At least I'm feeling I've got a helpful and trustworthy crew looking after the Van now.
Just had to move to Canada for that 😂 how ironic.
So far, no problems. I will take it for a long run in 2 weeks time and see if it stays that way!
Thanks for your help!!

View attachment 303703
Click to expand...

If the previous repair attempt involved separating the cooler and valve I suspect that the stainless steel / silicone rubber gasket between the two was not replaced.
Reason; I was searching for this gasket when I was rebuilding the same type EGR unit and the only place I found it available was Brazil.
Without replacement it is highly likely to leak.
 
No wonder some folk get their EGRs blanked off or removed. Illegal yes but very tempting. I had mine replaced at great cost and then the coolant pump as well the following week.
 
I wasnt tempted. Instead I did my homework prior to buying and avoided the most troublesome variants. Thats nefer a guarantee, but you play every card in the deck.
 
Sorry just jumping on this thread as facing similar coolant loss woes. We have T6 2016 T30 which we've had 7 weeks. Loosing coolant. Independent VW garage said that it was most likely the EGR cooler so we had that replaced last week. We also had the water pump and cam belt done too as these were due. A week later we are still loosing coolant and there is a slight hiss when we open the cap. Any thoughts? Could it be an airlock? Or could this be a sign of head gasket failure?
 
I know your pain!! My diagnosed EGR failure turned out to be a leaking coolant pump. VW jump straight to EGR failure for coolant loss - feels like a good money spinner.
 
Wildcamper said:
I know your pain!! My diagnosed EGR failure turned out to be a leaking coolant pump. VW jump straight to EGR failure for coolant loss - feels like a good money spinner.
Click to expand...
We've had ours at an independent garage who we have used before and they were fairly confident in EGR. Hmmm might have to give them a call.
 
A failed head gasket would give smoke/steam from the exhaust and you would see mayonnaise in the oil filled cap and on the did stick. Have you had a pressure test done on the cooling system.
 
dakeen said:
No I haven't yet, might be next port of call!
Click to expand...
After a thorough external check for leaks inc’ engine driven water pump (timing belt cover off).
The garage should have done a combustion leak test (sniff test) on the engine coolant, this would identify if the head gasket was leaking and takes minutes.
Does the coolant leak on a cold engine, hot engine or both?
They could also carry out a pressure drop test according to the answer above, if leaking on both a hot and cold engine then apply the pressure test when hot and leave until the engine is cold. The dis-advantage of hot to cold or vice-versa is that the gauge value will be void as the coolant contracts.
To identify a small leak it may take 12 hours.
Don’t let the garage randomly renew components at your expense.
Potential hidden leak points;
EGR Cooler (pressure test, steam in exhaust gases, strip down and check for deposits from coolant)
Cylinder head (sniff test, pressure test, engine oil emulsification, residual pressure in cold coolant reservoir in SOME cases, bubbling coolant with engine running, steam in exhaust gases).
DSG oil cooler (if automatic gearbox), major gearbox damage! (check gear oil for emulsification).
Charge air cooler (if your engine variant has a water cooled charge cooler and not an air cooled intercooler, pressure test, steam in exhaust gases, remove and check for deposits from coolant)
Cabin heater matrix, should be obvious as you’ll smell it.
Engine driven water pump seal (remove timing belt cover and look for deposits from coolant)
 
Last edited:
DXX said:
After a thorough external check for leaks inc’ engine driven water pump (timing belt cover off).
The garage should have done a combustion leak test (sniff test) on the engine coolant, this would identify if the head gasket was leaking and takes minutes.
Does the coolant leak on a cold engine, hot engine or both?
They could also carry out a pressure drop test according to the answer above, if leaking on both a hot and cold engine then apply the pressure test when hot and leave until the engine is cold. The dis-advantage of hot to cold or vice-versa is that the gauge value will be void as the coolant contracts.
To identify a small leak it may take 12 hours.
Don’t let the garage randomly renew components at your expense.
Potential hidden leak points;
EGR Cooler (pressure test, steam in exhaust gases, strip down and check for deposits from coolant)
Cylinder head (sniff test, pressure test, engine oil emulsification, residual pressure in cold coolant reservoir in SOME cases, bubbling coolant with engine running, steam in exhaust gases).
DSG oil cooler (if automatic gearbox), major gearbox damage! (check gear oil for emulsification).
Charge air cooler (if your engine variant has a water cooled charge cooler and not an air cooler intercooler, pressure test, steam in exhaust gases, remove and check for deposits from coolant)
Cabin heater matrix, should be obvious as you’ll smell it.
Engine driven water pump seal (remove timing belt cover and look for deposits from coolant)
Click to expand...
There was deposits of coolant in the EGR so we had that replaced. We also did water pump and cam belt at the same time as it was due. Thank you for the list of other things, ill look into those. Our van is a 2016 T30 2l 150 with DSG gearbox
 
dakeen said:
There was deposits of coolant in the EGR so we had that replaced. We also did water pump and cam belt at the same time as it was due. Thank you for the list of other things, ill look into those. Our van is a 2016 T30 2l 150
DXX said:
After a thorough external check for leaks inc’ engine driven water pump (timing belt cover off).
The garage should have done a combustion leak test (sniff test) on the engine coolant, this would identify if the head gasket was leaking and takes minutes.
Does the coolant leak on a cold engine, hot engine or both?
They could also carry out a pressure drop test according to the answer above, if leaking on both a hot and cold engine then apply the pressure test when hot and leave until the engine is cold. The dis-advantage of hot to cold or vice-versa is that the gauge value will be void as the coolant contracts.
To identify a small leak it may take 12 hours.
Don’t let the garage randomly renew components at your expense.
Potential hidden leak points;
EGR Cooler (pressure test, steam in exhaust gases, strip down and check for deposits from coolant)
Cylinder head (sniff test, pressure test, engine oil emulsification, residual pressure in cold coolant reservoir in SOME cases, bubbling coolant with engine running, steam in exhaust gases).
DSG oil cooler (if automatic gearbox), major gearbox damage! (check gear oil for emulsification).
Charge air cooler (if your engine variant has a water cooled charge cooler and not an air cooler intercooler, pressure test, steam in exhaust gases, remove and check for deposits from coolant)
Cabin heater matrix, should be obvious as you’ll smell it.
Engine driven water pump seal (remove timing belt cover and look for deposits from coolant)
Click to expand...
Sorry I replied earlier but got some of my info wrong. The EGR cooler matrix had failed internally (seen with mechanic). So that's why we replaced that too as it would have needed done regradless
Click to expand...
 
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