Bad coolant leak issue

[Fastblack]

2002 1.9TDI ran out of MOT yesterday - no big issues there.

 

However its been plagued by a serious coolant leak, overheating, boiling over, airlocks in the system for several months now, none of which my mechanic of self have been able to resolve.  Can make it 50 miles with no problem, or it can boil after 4 miles.   Right now its been sitting for 2 days with no coolant in the upper rad hose and expansion tank is full. 

Replaced several seals, hose clips and so on but no obvious signs whats casuing the problem.  Latest thoughts from mechanic is the leak is in heater matrix, which appears to be a right pain in the Kirkstone Pass to get to.  Complete dashboard/fascoia disassembly according to Haynes, also involving drilling out sections of supporting metalwork and fabricating new bits  🤬

 

Is it really that bad if that's where the leak indeed is?   Car due MOT now but no point putting it through if coolant issue is to be a major operation at just short of 220k miles.  Might be a breaker once I've removed everything which fits my vRS........including a fine set of winter wheels.

[Breezy_Pete]

Heater matrix leaks tend to result in steamy windows and the cabin smelling of antifreeze, so if you're not getting that I think you're barking up the wrong tree.

Check the expansion tank for residual pressure first thing in the morning after it's been driven the evening before.

[Tech1e]

Doesn’t sounds like a great deal of logical diagnosis has gone on here. 

 

- has the cooling system been pressure tested?

- do you have a physical leak?

- has the cap been tested?

- has the cooling system been tested for exhaust gas?

- has the thermostat been checked?

- is there coolant flowing back to the reservoir via the return?

- do the cooling fans operate?

- does the heater get hot?

[Fastblack]

 

 

- has the cooling system been pressure tested?.................................yes

- do you have a physical leak?...............................................................not a visible one

- has the cap been tested?.....................................................................no

- has the cooling system been tested for exhaust gas?.....................don't know

- has the thermostat been checked?....................................................yes

- is there coolant flowing back to the reservoir via the return?........yes

- do the cooling fans operate?..............................................................yes

- does the heater get hot? ....................................................................sometimes yes, sometimes no

[Tech1e]

Not a visible leak? So it has an invisible one?

Edited 8 September, 2019 by Tech1e

[Fastblack]

If you want to put it like that, yes.   Coolant is going somewhere but we can't identify where.  Car runs perfectly apart from coolant loss/overheating

 

[Tech1e]

Sounds like a head gasket then. 

[KenONeill]

@Fastblack - Well, I'd agree with @Tech1e about the likely HGF, but for all it costs I'd try a replacement pressure cap first.

[Tech1e]

Curious as to why the cap wasn't tested when the cooling system was?