Coolant problem

[pipek123]

Hello petrolheads,
I have some problems with coolant disappearing in my Forester 2.0Td 2012 (EE20Z Euro5 diesel engine). Last year when I bought it I had to replace the coolant reservoir, I've flushed and cleaned all the hoses and radiator and put in blue coolant as recommended.
After a couple 100km coolant became brown (it stayed brown since then no matter what) and started disappearing a little but there wasn't any foam or bubbles in coolant, oil was as new and level was the same as when I replaced it.
In summer I had to top it up every ca. 300km, but then in the winter I went over 5000km without losing any coolant but now when it's summer again I have to top up again every ca. 300km (after that reservoir is usually completely empty).
There isn't any visible leaks under the engine, engine runs fine and it doesn't smoke (except black when you floor it hard)
Last week I did the oil change and oil was at the same level as last year also it didn't have any signs of coolant (oil cap and radiator cap are both without any foam)

Does anyone know what else should I check and replace? It could be blown headgasket?

Thanks

 

[Ecmbuster]

Pressure test the radiator cap
Pressure test the cooling system
Make sure no coolant enters the oil pan
A more difficult test is at the injector (removed) port and perform a leak down test.
All tests need to be performed cold or ambient temperature.

 

[pipek123]

Did the pressure test today and it was all okay, no coolant in oil and no oil in coolant. The guy said that the brown color could be from the sealer (idk if previous owner tried to seal it). He is assuming that it could be bad headgasket..?

 

[Ecmbuster]

That is the AHA moment and not the best sign. That type of chemistry will eventually plug / restrict coolant flow to other components.
Have an expert confirm that assumption and perform the correct repairs.

 

[keith3267]

First Subaru has a "Coolant Conditioner" (made in UK) that seals up very small head gasket leaks and does NOT clog up the system. It does not work if the leak gets more than about a cup (1/4 liter) a month.

But, do you have an automatic transmission? If so, have you checked your ATF. You might have a pin hole leak in the cooling coil at the bottom of your radiator for the transmission. This will damage the transmission long before it damages the engine.