hey any updates?  

I've been a bit slack from updates but anyways I got the car back about three weeks ago from mech. Seemed okay for about a week or 2. It's not slowly overheating anymore but the temperature gauge is erratic now and it just flips up to max - seems to stay there for quite a while. Usually it comes down when I step on the throttle to let the water pump circulate. Mech says if it overheats when I drive hard then it could be head gasket  It just gets worse LOL. I've never been able to track this car since I bought it
Today was the second time gauge spiked again. Felt the radiator and it was cold.
I'm gonna try get a coolant pressure test to check HG's integrity. If that's good then next I'm gonna change ALL the hoses to OEM Beams + modify the radiator to have a proper bleeding hose. Gonna be a bit of a struggle seeing as I just quit my job and exams coming up fast but I need to be ready for Wakefield so I can't hold back
Been having thoughts of swapping the car for a Clubman but I've decided to keep it til Nationals next year...

If you tell me you didn't make sure you had the A/C set on full HOT and the fan going 100% WHILST you were bleeding the car WARM, then i'm going to laugh.

Huh? A/C? You mean heater? It's been set to hot for months now making me all nice and sweaty...
Last method I used was winding the filler cap to one click and letting it warm up (not hot), then open bleed valves and checking the level after.
Laugh anyway

Yes, though you have to get the level of the coolant from the bleed valves to be higher than the filler cap, otherwise you risk bleeding air into the system. some cheap plastic hose from Bunnings or similar (clear) can be left on the end of bleed openings in the front.
 
a quote from 2009, explains it:
 
http://www.mr2australia.com/pop_printer_friendly.asp?ARCHIVE=true&TOPIC_ID=18660
 
 

Yeh mate I use those hoses lol I'm not some novice in this area. It would be a bloody mess if I didn't use it. If I had a dollar for every time I've refilled/bleed/flushed the cooling system on this car I would be..fairly rich hehe
Sorry if I sound frustrated it just gets annoying when people repeatedly suggest something you already know (like being patronised) but I do appreciate the help.
I'll say it again I've never had problems servicing the coolant before the engine swap, it's only after that this is playing up on me. I suppose the lesson here for me to learn (especially in my case) is if you wanna do something, do it right for the first time. Unfortunately I didn't have full control over making certain decisions on this car but I've definitely earned some experience the hard way. I can't go back in time but I can certainly try teach my kids! (hopefully they won't be as stubborn has me haha)
Anyways I took the car for a hard run around the block at optimum temp earlier today, no needle fluctuations so it seems okay for now. I'll sort this **** out after exams
It sucks BIG time when car's unreliable but on better days it's hard to be disappointed by the short comings

I suppose it is necessary to update this post so new people reading know what's been tried etc. From the beginning:

1. New radiator. Beams engine swap. Radiator plumbing maybe sub-optimal, but it works. New thermostat.
2. Rusty coolant from swapped engine. Temp gauge erratic. Proceed to flush the coolant. Tested thermostat (submerged in hot water) - measurement within specs, working fine. Instructions for flush/bleed/refill is followed religiously from BGB and Reddtarga (MR2 Veteran).
3. After refilling the coolant, engine slowly overheats after getting up to optimum temperature. Radiator cold. Let car cool off for ~10 mins. Drive car hard. No problems. This scenario repeats at least 3-4 times, after refilling coolant. Changed to genuine thermostat. No difference. Give up.
4. Take it to mech. Report: Thermostat opens very slowly - only after 10-15 mins. No overheating episodes. Temp sensor tested and it works fine.
5. 20/10/12. Temp erratic again. Raises fists to the heavens.

Today:
After heading home from church, temp spikes. I pull over. Radiator is cold. Wait for the car to cool off. Temp gauge erratically comes down a few times. I turn ignition to ON and off several times and notice that each time I turn it ON, the temp reduces lower and lower until it's above cold the mark. This indicates that the thermostat is slowly opening while the car is cooling down. But this is nothing new. The only difference here is that it spikes instead of gradually overheating. I drive home in peace. Radiator is now hot. 
 
So the big issue/symptom is that: Thermostat opens very late - ~10 mins


In conclusion here are the potential problem areas and solutions that I think most of you will agree to:
Head gasket - not providing enough seal to pressurise coolant in the system. Once the thermostat is open however temps seem to stabilise. Mech says there's a potential this is the issue if driving it hard causes temps to rise.
Solution: Cooling system pressure test. I think before spending any more $$$ this is the way to go so as a logical process of elimination so I'll know what to do next. I'm broke anyways.
Coolant plumbing - engine was swapped by incompetent mechanic. Water plumbing maybe not the best although I'm not sure of the specific symptoms. Solution: Change all pipes hoses.
If a mech (specialist I might add) couldn't get rid of simple air bubbles what makes you think that air/bleeding is the problem?
So yeh anyone who says "you didn't refill coolant/bleed air properly blah blah" I'm just gonna ignore but don't take it personally now that you understand where I'm coming from. Actually it's probably better I ignore rather than respond in an aggravated matter
 

What about replacing the water pump? You might not be getting enough volume of water flowing around the system???

As a side note, where did you source the beams from. Any warranty?

Mrskylighter

What about replacing the water pump? You might not be getting enough volume of water flowing around the system???

That may also fit the symptoms, but as the mech said so could a leaking head gasket so maybe check that out first.
 
I remember reading a post by Road and Track, about one car that had difficult to diagnose cooling problems.
After trying just about everything else to fix it,  they finally discovered a non-genuine water pump insert had been fitted that had smaller rotors than stock and did not circulate the coolant properly.