Erratic cabin heat and temp gauge - air in the system?

[Johnny Graham]

Hi folks, my heater has started working intermittently, and the temp gauge keeps firing up to the red and back to normal, completely randomly. The car runs great, and there is plenty coolant in the expansion tank - with no signs of coolant being vented.

From a search, I guess that this is probably air in the system..? I realise to my horror that I meant to change the coolant before the winter, but have been distracted by life in general. The coolant is brown and doesnt smell very ethylene-glycolish, but the level in the expansion tank has never changed, so hopefully I have got away with it.....what a muppet.

Plan after a search is to drain/flush coolant, new thermostat, new rad cap, re-fill and burp the system..just wanted to see if anyone has any other thoughts..

Can I also double check that I am OK putting in a 50:50 water antifreeze mix (my MR2 needed the official toyota coolant) and ask what the capacity is? Edit - just found info on this, 10 litres of Toyota's own red brew coming up...

I was going to use the non-OEM thermostat from roughtrax, and save a few quid, unless there are any problems people know about?

Thanks in advance..gratuitous pic of my lovely surf on a beach in tiree below!

[Surfer Ross]

Hi folks, my heater has started working intermittently, and the temp gauge keeps firing up to the red and back to normal, completely randomly. The car runs great, and there is plenty coolant in the expansion tank - with no signs of coolant being vented.

From a search, I guess that this is probably air in the system..? I realise to my horror that I meant to change the coolant before the winter, but have been distracted by life in general. The coolant is brown and doesnt smell very ethylene-glycolish, but the level in the expansion tank has never changed, so hopefully I have got away with it.....what a muppet.

Plan after a search is to drain/flush coolant, new thermostat, new rad cap, re-fill and burp the system..just wanted to see if anyone has any other thoughts..

Can I also double check that I am OK putting in a 50:50 water antifreeze mix (my MR2 needed the official toyota coolant) and ask what the capacity is? Edit - just found info on this, 10 litres of Toyota's own red brew coming up...

I was going to use the non-OEM thermostat from roughtrax, and save a few quid, unless there are any problems people know about?

Thanks in advance..gratuitous pic of my lovely surf on a beach in tiree below!

Sounds like a good plan, that will get rid of any airlocks. The pattern thermostat from Roughtrax is a Blueprint ADL item which is as good as or better than a Toyota Original part.

[si tate]

Could be the thermostat is sticking causing the temp to fluctuate, just get it ALL done ASAP & you should be fine.

[Bogus]

Is there also plenty of coolant in the radiator ? Just checking whats in the expansion tank isnt enough.

Bogus

[Johnny Graham]

Thanks folks. Will check the radiator too - maybe I'm not out of the woods yet.
The fan is on full time now too, so hopefully its the thermostat..?

[Diezel Weazel]

Top up with Toyota (Red) Coolant only (no water)n you'll be fine ...

Jess
"Cos short cuts can cost more in the long run"