Oil Leak + Damaged Intercooler

[Chris Thomas-Dunn]

Hi all,

I've got an issue with my T6 that appears, on the surface, to be an excessive oil leak. Oil is collecting on the front grille and bumper, as well as pooling under the van.

I've been advised by my mechanic that my 'intercooler is leaking' but for all my reading online I can't understand why my intercooler would be leaking oil?

There is some visible damage to the intercooler shown below (no idea how this has happened, any insight welcomed) but I don't understand why this damage would cause an oil leak?

I've owned my T6 for 7 years now (66 plate 63k miles) and this is the first significant problem i've had with it, so i'm feeling rather nervous that I am entering an expensive world of pain!

My mechanic is suggesting replacing the intercooler and while the front bumper is off, locating and fixing the oil leak. My worry is that the source of the oil leak might be the crank seal as that seems to be a common but expensive root cause.

Any and all advice welcome as to how to approach this issue.

Cheers!

 

[Chris Thomas-Dunn]

I forgot to ask, is the damage to the intercooler significant enough to warrant replacing? Locating the oil leak is my number 1 priority however the mechanic is adamant to replace the intercooler.

 

[Lubrown]

There is some visible damage to the intercooler shown below (no idea how this has happened, any insight welcomed)

The wife?

That’s what some people say, anyway.

 

[Lubrown]

My mechanic is suggesting replacing the intercooler and while the front bumper is off, locating and fixing the oil leak.

To me this sounds like a valid suggestion- no point driving around with a damaged intercooler and, while it is off, surely it’s easier to get to the front end of the engine to see about the leak?

How much oil is it losing?

What’s the reluctance to do the intercooler? Are you saying you’re thinking of selling the van if the oil leak is going to prove expensive?

 

[Chris Thomas-Dunn]

To me this sounds like a valid suggestion- no point driving around with a damaged intercooler and, while it is off, surely it’s easier to get to the front end of the engine to see about the leak?

How much oil is it losing?

What’s the reluctance to do the intercooler? Are you saying you’re thinking of selling the van if the oil leak is going to prove expensive?

Seems logical to replace the intercooler and I have no issue overall with replacing it (I am not looking to sell under any circumstance), but I feel replacing the intercooler should be secondary to locating and fixing the oil leak?

I'm nervous that my mechanic will replace the intercooler without fully diagnosing and resolving the oil leak, leaving me £400 lighter and still with an oil leak.

It's hard to say how much oil it is leaking, it has just had a full service last week so I plan on checking the oil level fairly regularly from now on!

 

[manfrotto]

It could just be the intercooler, and nothing else. See this thread....

Thread 'P0101 00 [237] - Implausible Signal'

10 Sep 2025

Hi All,

I recently had my engine light come on the dash and VCDS returns the following code: P0101 00 [237] - Implausible Signal

I tried cleaning the MAF sensor with Archoil cleaner spray, I reset the code with VCDS but the engine light returned after about 20mins of driving.

So I replaced the MAF sensor, cleared the codes with VCDS and again the engine light returned after about 20mins of driving.

So it seems that the MAF sensor isn't the problem.

I have no other error codes displayed with VCDS so not sure what to check.
The intercooler looks ok, no hissing or anything but I can't...

• Shanz
• Replies: 30
• Forum: Engine, Gearbox, Exhaust, Drivetrain

 

[Chris Thomas-Dunn]

It could just be the intercooler, and nothing else. See this thread....

Thread 'P0101 00 [237] - Implausible Signal'

10 Sep 2025

Hi All,

I recently had my engine light come on the dash and VCDS returns the following code: P0101 00 [237] - Implausible Signal

I tried cleaning the MAF sensor with Archoil cleaner spray, I reset the code with VCDS but the engine light returned after about 20mins of driving.

So I replaced the MAF sensor, cleared the codes with VCDS and again the engine light returned after about 20mins of driving.

So it seems that the MAF sensor isn't the problem.

I have no other error codes displayed with VCDS so not sure what to check.
The intercooler looks ok, no hissing or anything but I can't...

• Shanz
• Replies: 30
• Forum: Engine, Gearbox, Exhaust, Drivetrain

Cheers for sharing that thread.

The middle strap failing on the intercooler seems to be the common theme.

I'll get that replaced and let yous know how it goes.

Cheers

 

[NicolasH]

Cheers for sharing that thread.

The middle strap failing on the intercooler seems to be the common theme.

I'll get that replaced and let yous know how it goes.

Cheers

This happened to me Chris - it’s an easy fix. See this post:-

Post in thread 'HELP! P010100 - Mass or Volume Air Flow Sensor "A" Circuit Range/Performance issue [RESOLVED]'

3 May 2025

@mmi You are a LEGEND!

The old intercooler had corroded with two of the retaining straps rusted away. You can see where it was leaking. I fitted a new intercooler today (a genuine VW one, from eBay which I got for a bit of a bargain at only £96.18 brand new). The van drives much better, with improved MPG (late 30's). I've scanned the van again using Carista and there are no errors.

Thank you so much for your help.

Fitting the intercooler is straightforward. Remove the bumper, then remove the long, narrow plastic bracket followed by two bolts that hold the intercooler in place...

• NicolasH

• 

 

[Chris Thomas-Dunn]

This happened to me Chris - it’s an easy fix. See this post:-

Post in thread 'HELP! P010100 - Mass or Volume Air Flow Sensor "A" Circuit Range/Performance issue [RESOLVED]'

3 May 2025

@mmi You are a LEGEND!

The old intercooler had corroded with two of the retaining straps rusted away. You can see where it was leaking. I fitted a new intercooler today (a genuine VW one, from eBay which I got for a bit of a bargain at only £96.18 brand new). The van drives much better, with improved MPG (late 30's). I've scanned the van again using Carista and there are no errors.

Thank you so much for your help.

Fitting the intercooler is straightforward. Remove the bumper, then remove the long, narrow plastic bracket followed by two bolts that hold the intercooler in place...

• NicolasH

• 

Thanks i've just been looking at your post on a different thread, haha. I'm 100% going to proceed with the repair now.

One question I do have however is, where is the oil coming from? I am no mechanic but I wouldn't have thought the intercooler system could 'leak oil' as there wouldn't be any oil running through it?

 

[Sasquatch]

There will be oil within it, the amount depending on age and mileage.

 

[Chris Thomas-Dunn]

There will be oil within it, the amount depending on age and mileage.

So it's not technically 'leaking' oil, more a build up of oil to the point of saturation where it appears to be 'leaking'?

 

[Sasquatch]

In order for the oil to escape the intercooler there will need to be a hole of some sort.

 

[NicolasH]

This from ChatGPT

Your T6’s engine uses a turbocharger, which compresses air before it enters the engine. The intercooler then cools that air. The air that passes through this system isn’t just clean air — it also contains a fine oil mist from the turbo.

There are two main sources of that oil:

1. Turbocharger oil seals:
   • The turbo’s bearings are lubricated by engine oil under pressure.
   • Over time, a small amount of oil can seep past the turbo’s internal seals and enter the pressurised air stream.
   • This oil travels through the boost pipes and ends up collecting in the intercooler (because it’s a low point in the system).
2. 
   
3. Crankcase ventilation (PCV system):
   • All modern diesels have a Positive Crankcase Ventilation (PCV) or breather system that routes crankcase vapours (which include oil mist) back into the intake to be burned.
   • These vapours mix with the intake air upstream of the turbo, so again, some oil ends up through the whole intake system — including the intercooler.

 

[Chris Thomas-Dunn]

This from ChatGPT

Your T6’s engine uses a turbocharger, which compresses air before it enters the engine. The intercooler then cools that air. The air that passes through this system isn’t just clean air — it also contains a fine oil mist from the turbo.

There are two main sources of that oil:

1. Turbocharger oil seals:
   • The turbo’s bearings are lubricated by engine oil under pressure.
   • Over time, a small amount of oil can seep past the turbo’s internal seals and enter the pressurised air stream.
   • This oil travels through the boost pipes and ends up collecting in the intercooler (because it’s a low point in the system).
2. 
   
3. Crankcase ventilation (PCV system):
   • All modern diesels have a Positive Crankcase Ventilation (PCV) or breather system that routes crankcase vapours (which include oil mist) back into the intake to be burned.
   • These vapours mix with the intake air upstream of the turbo, so again, some oil ends up through the whole intake system — including the intercooler.

Cheers, yeah i'm just struggling to wrap my head around how a slightly damaged intercooler can result in such adverse effects! For some reason it just doesn't click with me. But I accept im no expert and will follow the advice i've been given here and hopefully my issue is resolved. I'll be sure to report back!

 

[Pauly]

My T6 broke a strap on the intercooler and it split and a surprising amount of oil came out of it
After tens of thousands of miles the tiny amounts of oil that blow by will collect in the lowest point and that’s the intercooler, anything that goes in cannot come out so it is feasible you are just seeing the build up of oil that is escaping ??

 

[PhillH]

You will get your head around it when your MPG goes back up and your van performs a lot better when accelerating. Mine drove like the handbrake was on when my intercooler split

 

[Chris Thomas-Dunn]

Update: I have decided to replace the intercooler myself and it has arrived today.

I ordered it from: Intercooler | GSF Car Parts

However I have a minor concern about the lack of metal straps!

Is this something worth disputing with the merchant? I was planning on doing the repair on Wednesday but don't want to do so if these missing straps are important!

Cheers

 

[DXX]

Update: I have decided to replace the intercooler myself and it has arrived today.

I ordered it from: Intercooler | GSF Car Parts

However I have a minor concern about the lack of metal straps!

Is this something worth disputing with the merchant? I was planning on doing the repair on Wednesday but don't want to do so if these missing straps are important!

Cheers

View attachment 307368

No metal straps on my OEM 2016 CFCA, no issues so far

 

[NicolasH]

My genuine replacement VW one has straps... If you check the technical drawing of the intercooler you've purchased, it shows straps.

 

[Chris Thomas-Dunn]

My genuine replacement VW one has straps... If you check the technical drawing of the intercooler you've purchased, it shows straps.

View attachment 307369View attachment 307370

Indeed, i've emailed GSF as I find this very misleading. Hopefully they respond quickly as I don't want to delay carrying out the repairs... But by the sounds of it, the straps are not essential?

Why is nothing straight forward