purple5ive
if the outgoing hose from the radiator is cold/ flexing that means theres no coolant going out from the radiator, which also means the radiator has air in it, which also means cooling fans wont come on...

In my situation both hoses were cold, the radiator fans did not turn on when it should of.
When i undid the radiator drain valve/plug i heard lots of bubbles moving around in the radiator before coolant came out.  Yet to see evidence of any leaks on my garage floor or underpanels when i was draining it
 

purple5ive
bleeding the MR2 is the most painfull and time consuming tasks ever. make sure you take the time and do it properly, if you think your done then drive it around and keep constantly checking the OVERFILL bottle, do not open the coolant cap (unless the car engine is stone cold/overnight scenario)

Ive marked the overfill bottle just then and ill keep it a close eye on it if it lowers
 

purple5ive
if you open when its warm etc the coolant will get sucked back into the engine (rather than draw from the over flow tank)

Sorry man, dumb question but can you explain how coolant will get sucked back into the engine if i open the radiator cap when its warn (car not running)?

rico

purple5ive
if you open when its warm etc the coolant will get sucked back into the engine (rather than draw from the over flow tank)

Sorry man, dumb question but can you explain how coolant will get sucked back into the engine if i open the radiator cap when its warn (car not running)?

cooling system works by pressurisation. more pressure more cooling, that's why race spec radiator caps have a higher pressure rating. the cars cooling system is kep at a constant temp. by the radiator dissipating heat and the radiator cap, maintaining a set temp.
 
anyway, when the cooling system gets pressurised by heat from the engine, and a set limit is reached (by the spring on the radiator cap) the pressure is relived via the spring in the radiator cap and some coolant ends up in the coolant overflow.
when the car is turned off the pressurised coolant has nowhere again to go and does the same thing purges into the overflow. (hence why its never recommended to open the radiator cap when hot)
 
 when coolant starts to cool down and the system de-pressurises it starts to draw back the coolant it previously pushed into the coolant overflow bottle (this time via the bypass hole in the radiator cap, I believe)
 
NOW
with the MR2 this can take a long time, so if you actually opened the radiator cap when it was lukewarm etc while ist still under pressure (albeit only a very tiny bit), it will loose pressure in the system, so its ability to suck from the overflow bottle is compromised and it sucks in air instead (via the now missing radiator cap) and disappears down the black S bend coolant hose (it doesn't suck in a lot of air, but just enough to disappear from sight when looking into the S bend hose from the top, if you squeeze the hose the coolant should be visible again)
this is what I was telling you not to do
 
so now normally people would top up coolant straight away up to the neck of the filler, put the radiator cap back on and start driving
what happens now is the coolant will again be pushed out into the overflow bottle as usual, but this time it will have a bit more than normal (due to you topping up at the radiator cap) do this too many times and the coolant will now start to spill over from the overflow bottle itself (this will happen when the car is running usually and you wont notice it)
 
anyway that's the main reason not to open the cap when warm, and not keep topping up everytime (thinking you have a leak somewhere etc) so always wait for cool down properly then check the coolant overflow first to see if level has dropped. if it hasn't then you can be sure that the main cooling system is full of coolant. (check if needed)  if it has dropped or is empty then further investigation is needed.
 
this is my take on the cooling system anyway and I could very well be wrong, but its what I do and go by
 
cheers

Rico
Firstly, this a fantastic detailed write up on your cooling issues. Far better writing than I could achieve!
 
There is a very good reason for the use of the green coolant. That coolant (the green coolant) is what is required for motorsport. Rory built the car with trackday's being the priority then street driving secondary. It is a CAMS requirement that red coolant is not used due to its properties when you drop coolant on the circuit it provides more slip than oil. It is closer to sliding on diesel. I know this after a BMW dropped its coolant line on entry to turn three at Eastern Creek. I had zero grip mid corner and ended up in the dirt at 100km/h instead of being on the track. This was caused by using red coolant as opposed to the green coolant which does not have the properties which create this risk. As you enjoy going to trackday's, for the benefit of your friends I recommend you stick with the green coolant. The green coolant is also more effective at temperature control. any circuit racer/trackday warrior will attest to this.
 
EVO65 (quickest SW20 at Eastern creek) and Highlander(2GR-FE V6, ex Colin Osbourne Production Sports car)  had a lot of temperature control issues. This was solved by replacing the radiator. If you still have the standard unit, it may be worth looking at this or removing and flushing it.    
 
 

Whilst I appreciate green may be required on CAMS events, I'd still prefer red. Not like this car competes in enduros with yours. I wouldn't run green just to help on an odd track day spill if it fails.

Secondly, the car overheated around the block. An alloy radiator won't fix that unless its replacing a dead stocker. Diagnose first & don't just change parts. I know first hand cos I replaced everything (cap, thermostat, lines, radiator service & hrs of bleeding) last time around before my cracked block revealed itself.

Regardless of what anyone says the factory (red in this case) coolant is what you should be using as it has the correct properties for the actual metals being used in the engine. Whilst the non genuine coolant will say on the bottle compatible with cast iron blocks and aluminium cylinder heads it does not mean it will work as well as the factory stuff. 
 
With regards to the BMW comment Steve that is very weird since BMW coolant is a blue/green colour, and certainly when i have some on the floor it feels just as slippery as the red Toyota of even red Holden coolant.
 
If a BMW uses the wrong coolant is causes all sorts of nastiness in a already fragile system (German cars use quite a high coolant pressure in a sealed system compared to a Japanese car and that is why you get spectacular explosions when you have a small leak)

Hi Rico,
 
Can I ask, where did you buy the backing plate for the gauges?
 
Cheers
Colin
 

rico
And unrelated bought a black finish single din 52mm housing for my gauges:

Very clean sw looks good! That gauge plate is clean I've been looking for something like that.

very nice

Try to stay calm, there's a pretty angry looking monster in your interior :-o

Col
Hi Rico,
 
Can I ask, where did you buy the backing plate for the gauges?
 
Cheers
Colin
 

rico
And unrelated bought a black finish single din 52mm housing for my gauges:
 

You can buy the gauge backing plate from ebay. Search for 52mm single din plate and it should come up
http://www.ebay.com.au/sc...din+plate&_sacat=0