Cooling issue with Toyota MR2

I've recently bought a Toyota MR2, but am having problems with air appearing in the coolant.

I've changed for new the following:

Radiator
Major cooling hoses
Water pump
Thermostat
Rad cap

I've also checked all small hoses, compression and the cylinders. I've also carried out a coolant pressure test found a few small leaks and fixed them. The headgasket tester for exhaust gasses has also passed fine. Any ideas?

Asked on 12 November 2014 by jaydee chris

Answered by Honest John
An MR2 turbo is not a UK market car, but of course you know that. How is the turbo cooled? I'd guess that, as well as standard oil cooling from the engine oil flowing through the turbo bearing, it will be water-cooled, and the temperature around coolant as it passes through the turbo will be higher than anywhere else in the engine. I'd guess that is the point where evaporation is occurring, causing the oxygen in the coolant.
Similar questions
I changed the oil and filter on my 2012 Ford Fiesta. Now the engine fault light is on and the turbo isn't working.
My Ford Focus 1.6 TDCi runs fine for 35 - 40 miles, then cuts out as if the ignition was turned off. When I stop and turn off the ignition and then restart it then it runs fine. This is a repeating problem....
My 2005 Ford Mondeo 2.0 TDCi has done 147,000 miles. It had a previous issue where the glow plug light would flash and it would go into limp mode. I read various posts on here and it seemed that the arm...
 

Value my car

Save £75 on Warranty using code HJ75

with MotorEasy

Get a warranty quote

Save 12% on GAP Insurance

Use HJ21 to save on an ALA policy

See offer