Coolant drainage

[TomTom]

So most people will have heard about my recent head gasket fun and story. My cars been running nicely since I got it back several months back. I've kept a close eye on things, but the past 2 weeks I've let if slip and haven't been checking so regularly. After heckling last night my reservoir was sitting below the "low" mark, now when I got the car back it was sitting on the low. So it's extremely close to empty, first thing I'm doing tomorrow is going shopping for some topup coolant of the same brand.

My question is how fast does coolant drain? My reservoir is close to being bone dry, how many litres would the car generally hold, I haven't seen any drain back into the reservoir which is what's making me worry.

I've had a really good look under and throughout the engine bay, no signs of coolant or leakage from what I can see. And about 3 weeks after I had the work done NRG did a look over the car again, I got the thumbs up. Am I just being over paranoid and should too it up?

Thoughts?

[Deep Heat]

Coolant should not be draining, however the temperature of coolant and pressure in the system will affect the reading on the tank.

I would top it up to full and if it drop below low again take it to a mechanic, chances are its something simple like a worn radiator cap stopping it pressurizing properly.

[TomTom]

Coolant should not be draining, however the temperature of coolant and pressure in the system will affect the reading on the tank.

I would top it up to full and if it drop below low again take it to a mechanic, chances are its something simple like a worn radiator cap stopping it pressurizing properly.

Caps were replaced, but not by a Subaru specialist. He replaced them twice to get the right bar. This was during blown head gasket diagnosis. Surely coolant evaporates eventually, considering water mix/ratio? It hadn't drained at an alarming rate, but I'll certainly be filling it up.

[Deep Heat]

Caps were replaced, but not by a Subaru specialist. He replaced them twice to get the right bar. This was during blown head gasket diagnosis. Surely coolant evaporates eventually, considering water mix/ratio? It hadn't drained at an alarming rate, but I'll certainly be filling it up.

It does but it is at such a low rate it would take months if not years for it to have a substantial impact, remember it is a closed loop and any loss would be due to a leak, coolant evaporating through silicon hoses would take a long time.

To put it in perspective in the last 3 year I might have had to add 100ml of coolant.

[DownUnder]

Not just that, also remember that coolant changes the properties of the water. It raises the boiling temp which is an important factor in evaporation. It would take a long time to lose as much level as you're describing. It could just be air bleeding out of the system and coolant taking its place?

[Boostaddict]

Not just that, also remember that coolant changes the properties of the water. It raises the boiling temp which is an important factor in evaporation. It would take a long time to lose as much level as you're describing. It could just be air bleeding out of the system and coolant taking its place?

Yeh sounds right.

Tom, dont fill it. Just ring Nick and ask if thats normal. He is there on saturday !

[TomTom]

Not just that, also remember that coolant changes the properties of the water. It raises the boiling temp which is an important factor in evaporation. It would take a long time to lose as much level as you're describing. It could just be air bleeding out of the system and coolant taking its place?

Yeh sounds right.

Tom, dont fill it. Just ring Nick and ask if thats normal. He is there on saturday !

Had a chat to Nick he said just top it up to the low point and just bring it in next week for a checkup. Best be safe than sorry!

[TomTom]

I undid the radiator cap to have a good check today, it was full i noticed some coolant drained into the reservoir as i took it off. After a bit of a drive to supercheap it's sitting back on the low mark again (where it was when i got my car back a few months ago). I'll check the levels again when the car cools down.