Coolant leak / Mystery - help!! SOS!!

[Dellmassive]

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.

 

[Nik]

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.

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.

Thanks for this hit/tip. We did purge the system once the charge cooler was refitted.

 

[Bigsidavies]

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.

Is this the same item?

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

This Uprated Intercooler is a direct replacement for the Standard Intercooler found on both the 1.9 & 2.5 TDi VW Transporter T5, Here at Darkside Developments we only own and work with TDIs, so you can be assured that you are dealing with experts who have an in depth knowledge and understanding...

www.darksidedevelopments.co.uk

 

[Loz]

Is this the same item?

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

This Uprated Intercooler is a direct replacement for the Standard Intercooler found on both the 1.9 & 2.5 TDi VW Transporter T5, Here at Darkside Developments we only own and work with TDIs, so you can be assured that you are dealing with experts who have an in depth knowledge and understanding...

www.darksidedevelopments.co.uk

NO, that is an intercooler.

see; Which Radiator/Cooler (Guide)

 

[Bigsidavies]

NO, that is an intercooler.

see; Which Radiator/Cooler (Guide)

I wasn’t sure if they were the same thing Loz. Thanks.

 

[Nik]

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!

 

[Nik]

Little update - fitted the new charge cooler yesterday, hopefully that’s the issue resolved.

 

[Nik]

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!

 

[Llama35]

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

 

[Llama35]

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.).

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.

 

[Paynewright]

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.

Are you sure thats not a DPF regen?

 

[Loz]

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.

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?

 

[DXX]

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.

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.

 

[Llama35]

Are you sure thats not a DPF regen?

I’m not sure at all. I’m afraid I don’t know about these things. That’s why the van goes to the mechanic when anything is wrong with it

 

[Broadside]

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!

 

[Llama35]

Update from me. Decided to replace the egr which will be done next week. I’ll report the outcome of that as it becomes apparent

 

[Fluff34567]

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.

Don't believe they do one for the T6, I did ask but no reply.

 

[JFWerkstatt]

Mine was doing the same, EGR replaced, problem solved. Had it done at a local garage, including a cambelt and waterpump it was £1500.

 

[BOOSHAN]

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?

 

[Broadside]

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?

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.