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Discussion Starter · #1 ·
Hello,
My B10 BiTurbo (#45) somehow looses cooling liquid. While quiet driving no losses, but if i drive agressively with high rotations and turbos working - it may loose to 1 litre of coolant for 3 days.
Need to mention that visual inspection gave no results: no leaking, smokes, smell.
Anybody have ideas where to look for?

Many thanks.
Igor
 

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Any puddles under the car after parking it? Not sure if it applies, but my n/a 635 was pushing coolant out the overflow tube after parking it with the engine hot. Turned out to be a bad cap on the resevoir tank.
 

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Discussion Starter · #4 ·
Nothing was found on the ground after parking. The cap is OK and no leaking out of it. (Unfortunately).
As to the temperature - I have a greate story of that. On high speed (my max. was 280 km/h with some space for development (the car could do more but that was too frightening on Russian roads)) the temperature normally stands OK, but till the moment when as I guess it had lost some colland. On the speed say 160 km/h the air inflow still is capabale to cool the engine with less collant volume and I do not see the danger. Next, it seems when the lack of coolant reaches critically low volume, happens very quick temperature growth and the engine on the lower speed or traffic ligh stop can simply boil.
This puzzle with the car could not be solved for some time already. There are not visible breaks on the engine or in-out air flow ways. The turbines are new (~5000 km). The effect was noticed before and after new turbines were installed.

Igor
 

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You could have a pinhole leak somewhere that doesn't open up until the system gets to a high enough temperature (pressure). I'd be looking for evidence of dried up coolant remains for a lead to finding the issue.
 

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Sounds a lot like a headgasket failure to me. If you can get access to a 'CO2 sniffer' use that to check for exhaust gasses in the coolant.
 

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Do the simple cooling system pressure test. It will show you the leak. If not, do the cylinder pressure test and cylinder leak test. Then you will know what is wrong.
Jan
 

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This sounds very similar to what I just went through with my B11 3.5... none of the classic symptoms but it was pressurizing the cooling system when hot and spewing coolant out the reservoir cap... upon pulling the head we couldn't see anything wrong with the HG but sent it to the machine shop and they confirmed it was broken. I never smelled it, and never mixed coolant or oil... guessing the leak in the HG so small it only opened up on the compression cycle.
 
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