Coolant Loss

[Beastrider]

I don’t know for certain about the SWB version but I expect you are right that it doesn’t have the rear heater. The OP has a 95 so could still be relevant for him.

 

[karl2000]

Just back to basics, but was the system properly bled when the coolant was last replaced?

 

[Aeroelastic]

Just back to basics, but was the system properly bled when the coolant was last replaced?

Sorry this meant for me? I revive this thread that was 2 years old. But for my Prado, not sure what happened when I bought 18 month ago, if the Previous owner bled the system and how it was done.

But I thought Toyota cooling system will self bleed? That’s what happen to my Lexus Rx400h when I changed the radiator last year, it took 3-4 runs to bleed the system by driving around and top up, but then the coolant remains at steady level after that.

 

[MisterCruiser]

@Aeroelastic - But back to even more basics, do you actually have a leak? if the rad level never drops, and only the header tanks level changes or even empties sometimes, then I think that's normal and that there is no leak. Can anyone confirm? My cruiser does exactly this behavior, surely if the rad level never drops then there is no leak irrespective of what the header tank is doing.

If you have a leak with either heater matrix or pipes then surely eventually your rad level is going to drop as it's all 1 big shared circuit?
That's my understanding / experience of it anyway.

You could be chasing something that's not there.

 

[Aeroelastic]

I do hope that is the case. I thought if the expansion bottle is empty, when the engine cool down it will suck in air and caused air bubble in the system?

 

[Beastrider]

My apologies - I didn’t notice the original post date.
The intention is that the pressurised part of the system (everything except the expansion tank) should remain full of fluid at all times. You should only ever see fluid when you open the pressure cap. The expansion tank fluid level will rise as the system heats up and then reduce again as the system cools back to the original level. From what you describe, Aeroelastic, your system is operating as it should. You may get some evaporation losses from the expansion tank over time and that may be what you are noticing over 3-4 months. Keep monitoring the expansion tank level (when engine is fully cold) and keep it at exactly at ‘Max’ so you can detect and measure any loss.