Lost coolant but didn’t overheat???

Hi Everyone
Hopefully someone can help me explain this. My 300zx twin turbo is leaking from the cylinder head coolant outlet. It was rusted at the top of the pipe where the short hose attaches. The radiator leaks down to this level so it looks empty but still has about 4 litres sitting in it. I drove the car about 150kms during winter and luckily it didn’t overheat. Does anyone have advice on how I managed to do this without overheating?

 

Sounds like the coolant temp sensor wasnt submerged in coolant, so it therefore wasnt sending a reading.

Cars can survive being overheated (if your lucky) so your best bet is to fix the leak and see if it holds pressure amd temp.

Dont be surprised if the motor is now toast though.

 

"It was rusted at the top of the pipe where the short hose attaches."
This is the typical result of a poorly maintained cooling system.

"The radiator leaks down to this level so it looks empty but still has about 4 litres sitting in it."
Considering the TT engines cooling system contains 9 litres, I guess running it with 4 litres is OK.

Jinxed is probably correct in his analysis of what was happening concerning the temperature sender.
When an engine gets hot the area subjected to the most heat will be the cylinder heads especially in the area of the exhaust valves.
The parts that are susceptible to heat include the piston rings.
If they get hot enough, they'll lose tension & loss of tension will result in loss of compression.
The other item that is susceptible to heat is the engine oil.
For every 10 degrees rise in engine temperature the oil life is halved & the protection the oil provides to critical components such as crankshaft bearings, rod bearings & particularly valve train components such as cams & lifters is significantly reduced.

If you've driven the vehicle for 150kM with 4 litres of coolant (& I use the term coolant loosely) in the cooling system then chances are the engine may of sustained damage/wear.
An engine compression test could be advised.

 

Mate, I feel your pain. Hope you haven't cooked your engine, that's some serious wallet ouch if you have.

All TT's should have a coolant level sensor IMO, see this ancient thread for a DIY cost effective way to get one -
https://aus300zx.com/xenforo/index.php?threads/coolant-level-sensor-installation.304151/

And there are probably better and cheaper ways to do it by now but it must be done.

Good luck dude.

 

If there is only about 4 litres left in the radiator, then the system is only a litre or two down.

You can only get about 5 litres out of the cooling system when you drain the radiator.

Given the cooler winter weather, the stock temperature gauge would not have shown the increased coolant temps.