What does normal look like?

[Philhenf]

Hi everyone. I’m a newbie to California’s and to VW and I am looking to find out what normal looks like on the cooling system. I have the TDI 180 PS 4 Motion - 2013 plate with 38k miles. So... having topped up the coolant to the max is it then 'normal' for the level to drop below the min mark once the system gets to pressure and operating temperature? If so, is it then 'normal' for the system to retain its pressure (keeping the coolant below the min) for several days after a run? Is it also 'normal' for the coolant to then return to close to the Max mark when the cap is unscrewed (and when the system is cold) as the system depressurises and the pipes contract? It's already been back to the dealer as it was losing coolant. They say they found a weeping T-joint, but my bigger concern is the pressure that seems to be building up in the system to force the coolant out of the tank and which is not then dissipating. None of my other vehicles seem to force so much coolant out of the expansion tank when at temperature and even when there is some 'loss' it always seems to normalise back to the max mark when its cooled down. Any thoughts or suggestions gratefully received....

 

[Hotel California]

Hi and welcome on your first post .
Just a clarification , is it the engine coolant you refer to as this topic is started in "heating and air-con " witch actually is for aircon and heater questions....

 

[Philhenf]

Hi and welcome on your first post .
Just a clarification , is it the engine coolant you refer to as this topic is started in "heating and air-con " witch actually is for aircon and heater questions....

I posted in beginners...and it has been moved here ...it is the engine coolant

 

[calikev]

The expansion tank is there for a reason to accommodate the expanded water as it gets hot it shouldn’t drop when hot it should rise a little and then when it cools it should return to normal. If it is forcing water out of the bottle you have too much pressure either from a blockage or exhaust fumes entering the cooling system

 

[Tufty_B]

It seems to be overpressurising, a cause could be head gasket failure/warped head due to previous over heating.
A competent mechanic should easily be able to check using a hydrocarbon sniffer. If you're got a head gasket leak, you're pushing combustion gasses into the cooling system, as well and burning coolant.
This is a quick and easy test, so I'd ask for this to be done to confirm or rule it out.

 

[WelshGas]

Hi everyone. I’m a newbie to California’s and to VW and I am looking to find out what normal looks like on the cooling system. I have the TDI 180 PS 4 Motion - 2013 plate with 38k miles. So... having topped up the coolant to the max is it then 'normal' for the level to drop below the min mark once the system gets to pressure and operating temperature? If so, is it then 'normal' for the system to retain its pressure (keeping the coolant below the min) for several days after a run? Is it also 'normal' for the coolant to then return to close to the Max mark when the cap is unscrewed (and when the system is cold) as the system depressurises and the pipes contract? It's already been back to the dealer as it was losing coolant. They say they found a weeping T-joint, but my bigger concern is the pressure that seems to be building up in the system to force the coolant out of the tank and which is not then dissipating. None of my other vehicles seem to force so much coolant out of the expansion tank when at temperature and even when there is some 'loss' it always seems to normalise back to the max mark when its cooled down. Any thoughts or suggestions gratefully received....

Definitely NOT normal.
The system is being pressurised. 2 possibilities:-
1. Cylinder Head with a leak from cylinder to coolant channel

2. EGR Cooler which cools the exhaust gases on their return to the inlet manifold.

You need 1. A sniffer test of the gases in the Header Tank to show if the gases are Exhaust in nature
2. Head compression test

If 1 is + tve and 2 OK then it is the EGR cooler

Had this on my Puma Defender and it was the EGR cooler.

 

[Ryemslie]

Yeah as above it could be either. I'd say it's more likely to be the egr cooler tho.

 

[Philhenf]

Thank you for all the replies. I suspected as much when I was being told it was all normal by the servicing manager. Now to find out what the dealer means by its ‘no quibble’ money back guarantee!

 

[Spartan]

There are a couple of other threads on this subject but no conclusive answers I'm afraid. If nothing else, shows that this issue is not unheard of:

https://vwcaliforniaclub.com/threads/disappearing-engine-coolant.15888/
https://vwcaliforniaclub.com/threads/coolant-loss.103/

One suggestion: has the cambelt/timing belt been replaced recently? I believe it's common practice to replace the water pump at the same time. However, if there was a water pump problem, it could be that coolant is not being circulated properly, leading to overheating?

The tests already suggested will diagnose anyway I am sure. Good luck!