My 2016 Superb III 2.0 TDI 150ps, has started losing coolant since aroud 150K km when I had timing belt / water pump replaced. I dont know if its related or coincidental, the old water pump was seeping a little before this.

Its now up to 200K km.

 

The system appears to hold pressure in that any time I open the cap its still pressurised even when coolant is cold.

I can't see any sign of coolant leaks, in fact I'm still not quite sure where the coolant is going, although I suspect its going out the overflow in the expansion tank.

It appears to lose coolant when I top it up and  then seems to find a level below the minimum mark where it is fairly constant.

If i don't top it up it doesn't seem to lose much more, if i do it seems to lose most of the top up after a few hundred miles.

 

I left it for quite a while and it took about a litre of coolant to get it back up to the max mark cold.

 

On no occasion have I ever seen the temp gauge move above 90 deg mark.

The heating does work but I can't be 100% sure its as strong as it should be.

The coolant looks the correct colour and theres no gunk in oil.

 

The expansion tank is marked G13 "mit silikat ", but I can't access the bag as its behind plastic wall, so cant confirm if its intact.

 

I haven't had system pressure tested or sniff tested.

I have replaced the cap but with  no effect.

 

What would you do next ?

 

 

 

 

 

 

 

 

are you getting a low coolant warning on the dash ?

if not , i'd do nothing but monitor things

2 hours ago, ShotgunWillie said:

My 2016 Superb III 2.0 TDI 150ps, has started losing coolant since aroud 150K km when I had timing belt / water pump replaced. I dont know if its related or coincidental, the old water pump was seeping a little before this.

Its now up to 200K km.

 

The system appears to hold pressure in that any time I open the cap its still pressurised even when coolant is cold.

I can't see any sign of coolant leaks, in fact I'm still not quite sure where the coolant is going, although I suspect its going out the overflow in the expansion tank.

It appears to lose coolant when I top it up and  then seems to find a level below the minimum mark where it is fairly constant.

If i don't top it up it doesn't seem to lose much more, if i do it seems to lose most of the top up after a few hundred miles.

 

I left it for quite a while and it took about a litre of coolant to get it back up to the max mark cold.

 

On no occasion have I ever seen the temp gauge move above 90 deg mark.

The heating does work but I can't be 100% sure its as strong as it should be.

The coolant looks the correct colour and theres no gunk in oil.

 

The expansion tank is marked G13 "mit silikat ", but I can't access the bag as its behind plastic wall, so cant confirm if its intact.

 

I haven't had system pressure tested or sniff tested.

I have replaced the cap but with  no effect.

 

What would you do next ?

 

 

 

 

 

 

 

 

I'd strongly advise considering replacing the expansion tank for one without the silikat bag.

I had a constant, slow drop in coolant until I removed silica bag from my (single wall) expansion tank. I removed it to stop a future matrix blockage so it was more of a happy side effect.

I thought I burst the bag slightly when removing/forcing it out, but maybe it was already leaking.
 

 

 

Edited 12 June, 20241 yr by Alan_P

Looking for some assist / advice / stories about inner coolant troubles with ex AA vehicles. I sold an exAA T6 (150bph 2.Zero TDI) with 102k miles that has an internal coolant trouble. It has been losing coolant. The ERG cooler has been changed and the rate cooler has been tested from the place I bought it from. I have due to the fact that positioned it into VW for a diagnostic. They stress examined the engine which misplaced half of bar of stress overnight. Tested both EGR and rate cooler, which have been both first-rate. They then used a bore scope to look within the engine. Cylinder 2 was observed to have scratched / rating marks and determined proof of dampness in cylinders 3-four, however couldn't make clear what that became and so advocated stripping the pinnacle to investigate. Possibly the cylinder head gasket desires changing, but I'm not certain what the scratches/ rating marks suggest in cylinder 2. I'm guessing it's feasible that if coolant has been leaking into the engine it is able to have washed oil off the pistons and the metal on metal may also have caused it. My query is, if it's miles the gasket that needs replacing. Will I be searching at problems down the line from the scratches in cylinder 2? What are the potential troubles? Or wouldn't it be high-quality? The engine runs quality, nicely a part from the amber engine control mild has simply come on, but that is from low ad blue efficiency (the code that popped up) Has everyone had any enjoy of this?

 

192.168.1.1 192.168.100.1

6 hours ago, 310golfr said:

are you getting a low coolant warning on the dash ?

if not , i'd do nothing but monitor things

 

Yes its constantly on except for a short while after i top up.

 

After posting earlier today, I topped up the coolant whilst car was cold to half way between the 2 lines, took about a litre,  and stuck a piece of paper under the expansion tank.

The coolant warning came on after about 10 miles of driving. 30 miles later I got a chance to look at it :

no coolant on piece of paper - so hasn't come out of expansion tank overflow.

no coolant in the expansion tank. I opened the lid and when pressure released the coolant level came back up to similar level as I had filled it to. I got one small drip from the overflow whilst doing this.

 

 

 

 

On 13/06/2024 at 00:45, ShotgunWillie said:

 

Yes its constantly on except for a short while after i top up.

 

After posting earlier today, I topped up the coolant whilst car was cold to half way between the 2 lines, took about a litre,  and stuck a piece of paper under the expansion tank.

The coolant warning came on after about 10 miles of driving. 30 miles later I got a chance to look at it :

no coolant on piece of paper - so hasn't come out of expansion tank overflow.

no coolant in the expansion tank. I opened the lid and when pressure released the coolant level came back up to similar level as I had filled it to. I got one small drip from the overflow whilst doing this.

 

 

 

 

Any news since this post?

 

I've had similar coolant vanishing problems that 3 different garages couldn't diagnose. Also on a 2.0 TDI 150.

 

In the end, I decided to return the car to the dealer I bought it from, but still very invested in understanding what might cause these issues. Hopefully you resolved yours.

The problem is not the G13 or the silicate bag. The problem is in the "watercooler", it is a fault known by the brand and the repair is not cheap. I have filled 1.1 liter of coolant for 90k kms. TDI 2.0 190 HP 4x4.

Edited 30 June, 20241 yr by Gabrielem

Strangely the issue stopped happening.

 

I believe there was air in the system after the water pump change.

Whenever the coolant system got up to temperature and pressurised the level in expansion tank would drop as that air got compressed.

It would surge up again when cap was removed but never quite to the same level.

 

I think eventually the system managed to "self-bleed" the air but it took 10,000s of km to do so.