Coolant leak / Mystery - help!! SOS!!

Its worth pointing out that the water cooling system on these engines is very complex and requires a lengthy process to remove airlocks from the system.


Any time the water circuit is opened proper purging is required...

This involves running various revs and pumps in sequence as per the OEM process.

Letting it get hot with the cap off won't do it.


Some overheating problems are due to air in the system.
 
Hi all, so we have done more investigation today. We have checked the EGR and it’s bone dry, however the charge cooler is soaking, boost pipes wet and evidence of dried coolant on the outside of it too. So we think we have found the issue.
Question. Apart from VW - is there anywhere else I can buy one from?
VW have quoted £480 inc VAT.

Dellmassive said:
Its worth pointing out that the water cooling system on these engines is very complex and requires a lengthy process to remove airlocks from the system.


Any time the water circuit is opened proper purging is required...

This involves running various revs and pumps in sequence as per the OEM process.

Letting it get hot with the cap off won't do it.


Some overheating problems are due to air in the system.
Click to expand...
Thanks for this hit/tip. We did purge the system once the charge cooler was refitted.
 
Nik said:
Hi all, so we have done more investigation today. We have checked the EGR and it’s bone dry, however the charge cooler is soaking, boost pipes wet and evidence of dried coolant on the outside of it too. So we think we have found the issue.
Question. Apart from VW - is there anywhere else I can buy one from?
VW have quoted £480 inc VAT.


Thanks for this hit/tip. We did purge the system once the charge cooler was refitted.
Click to expand...
Is this the same item?

www.darksidedevelopments.co.uk

Darkside Uprated Front Mount Intercooler (FMIC) for VW Transporter T5 1.9 / 2.5, T5.1 & T6 2.0 TDi and 2.0 TDi Bi-Turbo Models

Darkside Uprated Front Mount Intercooler (FMIC) VW Transporter T5
www.darksidedevelopments.co.uk www.darksidedevelopments.co.uk
 
I’ve bought a new charge cooler from VW Vans Camberley. Great customer service and gave me a little bit off the price. Should arrive with them Friday morning and be fitted Friday afternoon with any luck!
 
Hi, so the latest update is replacing the charge cooler has not stopped the coolant leak? It’s now booked in on Monday for a pressure test / further investigation.
To be continued!
 
Interesting to read these threads. We have similar coolant loss on our 150bhp 2017 DSG model with no visible leaks. Had pressure test done and no leaks in system and I’m assured the head gasket is also fine.
Had dye put in coolant to see if egr valve could be the source but after 4 weeks there is no dye in that either.
Our mechanic is at a total loss.
We did get the engine management light on last year and the year before with error codes on the egr but they were reset and haven’t appeared since October 2021.
The coolant loss started this May.
I’m tempted to just replace the egr valve as it has faulted twice before but could spend £1200 replacing it and the problem still not be solved.
Any suggestions welcome
 
Loz said:
The other coolers known to go are the gearbox oil cooler ( will see water in the oil) and the charge air cooler (if you have one, depending on what engine you have.).
Click to expand...
How would you tell if it was the charge air cooler that had failed? Our engine does smell pretty warm after it is turned off sometimes. The fan keeps going which is normal but the engine smell doesn’t seem right to me.
 
Llama35 said:
How would you tell if it was the charge air cooler that had failed? Our engine does smell pretty warm after it is turned off sometimes. The fan keeps going which is normal but the engine smell doesn’t seem right to me.
Click to expand...
Are you sure thats not a DPF regen?
 
Llama35 said:
How would you tell if it was the charge air cooler that had failed? Our engine does smell pretty warm after it is turned off sometimes. The fan keeps going which is normal but the engine smell doesn’t seem right to me.
Click to expand...
Pressure test the water jacket in situ, the two coolant hoses are accessible, or maybe remove the output hose (the big black one on the front) and check for coolant after it has stood overnight before you start it?
 
Llama35 said:
Had dye put in coolant to see if egr valve could be the source but after 4 weeks there is no dye in that either.
Click to expand...
I’m not sure how the dye would be spotted in this case. It would require the EGR unit to be removed and stripped down. Also not sure that the dye would be present after the exhaust gas burns it off.
If you blank the EGR the coolant can’t be lost through the engine, this would have to be a temporary measure as would register a low flow rate unless you fit a Tafmet emulator at the same time.
 
My van (150ps) went in for investigation, it was left on pressure test for about 30hrs and dropped a negligible amount. The mechanic said if it’s losing coolant it’s not bad enough to spot easily so keep driving it until it gets worse. 1,200 miles later and it hasn’t lost any, so weird as the coolant dropped from normal max level down to fully empty triggering the coolant light in September so the coolant went somewhere. There must be a pixie in there drinking it occasionally!
 
DXX said:
I’m not sure how the dye would be spotted in this case. It would require the EGR unit to be removed and stripped down. Also not sure that the dye would be present after the exhaust gas burns it off.
If you blank the EGR the coolant can’t be lost through the engine, this would have to be a temporary measure as would register a low flow rate unless you fit a Tafmet emulator at the same time.
Click to expand...
Don't believe they do one for the T6, I did ask but no reply.
 
Mine was doing the same, EGR replaced, problem solved. Had it done at a local garage, including a cambelt and waterpump it was £1500.
 
My T6 150ps went in for coolant loss, around 300ml every 300 miles. Mechy told me to replace belt and pump before running up to temp, (it did need doing). Just driven 1600 miles and the light is back on. Mechy said next port of call, according to tech bulletin, would be looking at glow plugs. Has any one else had there plugs checked (not a euphanism) regarding coolant loss?
 
BOOSHAN said:
My T6 150ps went in for coolant loss, around 300ml every 300 miles. Mechy told me to replace belt and pump before running up to temp, (it did need doing). Just driven 1600 miles and the light is back on. Mechy said next port of call, according to tech bulletin, would be looking at glow plugs. Has any one else had there plugs checked (not a euphanism) regarding coolant loss?
Click to expand...
Well that is interesting… I had some coolant loss in September which cleared up by itself and now this week my van has started showing an EML and reporting an issue with glow plugs.
 
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