Please tell me it's not the head gasket - 2013 VW Amarok TDI420

[baskey]

Hi all,

So, I recently bought a 2013 VW Amarok TDI420 at auction. Couldn't inspect it at the time, so it was a risky move. Also sat in a warehouse for almost 3 months due to lockdown.

It definitely has an issue, which I currently suspect to be the head gasket, but I'm looking for confirmation or any alternative theories please, before I go and ask my mechanic to take it apart.

Symptoms:

1. Exhaust fumes (based on smell) in coolant expansion tank
2. Black 'soot-like' substance coating the coolant expansion tank
3. Cooling system is over-pressurising big-time. Coolant (water) is being forced up through the expansion tank lid valve. Just got new lid to make sure the valve wasn't faulty.
4. A bit difficult to start (though has a flat battery). Once started, sounds like it's running smooth, but also due to cooling system pressure, suspect a lot of air is being pulled into the radiator as there is a gurgling sound after running for more than a few mins.

Other notes:

1. Appears that the EGR has been blanked/deleted, so can't imagine that's causing the issue, unless the blanking process can somehow cause soot/exhaust fumes to end up in the coolant system??
2. No white (or black) smoke from exhaust currently.
   1. Running the cooling system with water currently as the level seemed to be dropping a lot initially (but after I've filled it up a couple of times and burped the hoses, it's not dropping any more, though I haven't run it for more than a few minutes at a time because it's bubbling straight away).
   
   
3. No obvious oil or coolant leaks around engine block, though coolant did empty fairly quickly on at least 1 occasion (possible that radiator wasn't full and just emptied into there, have since burped & checked the radiator which seems fine).
4. No obvious oil or fuel in coolant.
5. No obvious coolant in oil, no 'chocolate milkshake' or sludge currently visible.
6. Seems to be a very small amount of white smoke coming from a connection point between the turbo(??) and the exhaust(??) - not sure if I've got those parts right (see circled part of photo below). It only seems to happen on start-up, then disappears. Small amount of coolant/water sitting in compression chamber perhaps and smoke leaking from here?
   
   

I really hope it's not the head gasket. If there is anything else it could be that you've come across before, I'd really like to know. Thermostat valve? An issue with the blanked EGR? Water pump? I don't know what else could cause this.

Thanks in advance for any suggestions.

[Sharkie]

Could be the turbo? Its watercooled and if it failed internally (cracked) could be boosting into the coolant system somehow through the crack, especially if the oil is (and stays) clear. Not a cheap part that turbo ....

[baskey]

Could be the turbo? Its watercooled and if it failed internally (cracked) could be boosting into the coolant system somehow through the crack, especially if the oil is (and stays) clear.

Cheaper than a head gasket?

Thanks Sharkie, do you know if there's a way to test/eliminate it as a possible cause? Some way to isolate the turbo?

[Sharkie]

Cheaper than a head gasket?

Thanks Sharkie, do you know if there's a way to test/eliminate it as a possible cause? Some way to isolate the turbo?

No way to isolate whilst still fitted and part of the system I'm afraid. If you disconnect the coolant feed to it (which is what you'd need to do to test the theory), it will overheat very quickly and then fail catastrophically.

The only way realistically is to remove and visually inspect I'm afraid.

EDIT: actually, inspecting the coolant lines to and from the turbo may help. You'd need to remove some of it and inspect the insides for the soot you mentioned. I don't have the TTDI so can't help specifically. I could be totally wrong and the turbos could be oil-cooled only. That said, I have personally experienced this on a watercooled turbo before.

Perhaps have a look on ERWIN (Volkswagen AG erWin Online ) for scematics of the the turbo and its components. If you do, download everybit of documentation they have as it is all very useful and you never know when you may need something from it.