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MG MGF Technical - Coolant Circulation Problem

I have a problem with my 2002 MG TF160.
From cold the engine, radiator and heater heat up as normal, once normal running temperature is shown on the gauge coolant circulation appears to stop to the radiator and heater, engine temp. starts to rise and radiator and heater begin to cool.
I've changed the water pump, thermostat and checked both jiggle valves.
Any ideas? Thanks.
William de la Riviere

I should add I have vac filled and bled the system a number of times with no change.
William de la Riviere

This appears to be shouting air lock doesn't it? Odd that it seems so resistant to all your efforts to bleed the system.

Does the water in the bypass circuit always stay hot?

Might there be a problem with the thermostat?

When did the problem start? Has your car had any work on the coolant system performed recently?
Rob Bell

Rob, thanks. Yes bypass circuit stays hot and heats up with engine temperature and overheats with engine. The bypass hose has been changed as a precaution.
Head gasket was changed in March 07 including reconditioned head and improved gasket, new bolts etc. No work since, until this problem occurred a week ago.
Interestingly it has just failed a block test. An ex-MGR service manager I know thinks that the cooling system is so marginal that the slightest interuption of flow thru the head would be enough to stop the flow to rad and heater.
Head Gasket change coming up I think!
William de la Riviere

Ugh - I hope not, but HGF could explain recurrent air locks. Might also (and I really hope not!) suggest that the cylinder head has gone soft... :o(
Rob Bell

Sounds like you thermostat has failed or there is an obstruction in your cooling circuit. It is not recommended to use the car until you've detected the fault if another HGF is to be avoided. You should consider a PRT conversion - it is really not a big job. Then you'll get rid of all coolant flow problems as you will have a constant flow through the engine's cooling jacket.
[IMG]http://i80.photobucket.com/albums/j198/jonaf/PRT-1.jpg[/IMG]
Jon F

You can apdapt a Freelander PRT to fit the MGF/TF:

Jon F

Rob and Jon,
We've found that if you clamp off the by-pass system the heater will get hot again which suggests to me there's a blockage in the heater system that is preventing flow until you force it to flow. We removed the heater tap and back flushed the matrix all seems OK but the problem persists.
Once during the course of the above the rad went cold too. And on another occasion both the heater and the rad stayed hot, on this occassion we let the system cool down before starting up again and this time the heater went cold having heated up just as before.
T4 shows no faults with sensors.
This is maddening. Any clues anyone? There's got to be a BIG drink in it!
William de la Riviere

Going back to Jon's suggestion, does anyone do a kit of all the parts you need to convert to a PRT?
William de la Riviere

When I asked B&G for that last year, they were 'thinking about it' so I should say probably not yet...
C.R.B. Simeon

help!! simular problem to the above but i have only had mgf vvc for 4 days!!! driving the car today, everthing ok till i turn the heater control to hot...started to blow cold and then after a few minutes the engine temp went to hot...stopped immediately..as expected boliing water was arttempting to spill out of water expansion bottle...left engine to cool down and limped home...car apparently was sitting idle for 6 months before i bought it...its done 50k but had new head gasket etc at 38k so i dont think its the head gasket....any help would be greatly appreciated.
Paul

help!! simular problem to the above but i have only had mgf vvc for 4 days!!! driving the car today, everthing ok till i turn the heater control to hot...started to blow cold and then after a few minutes the engine temp went to hot...stopped immediately..as expected boliing water was arttempting to spill out of water expansion bottle...left engine to cool down and limped home...car apparently was sitting idle for 6 months before i bought it...its done 50k but had new head gasket etc at 38k so i dont think its the head gasket....any help would be greatly appreciated.
paulmarx

help!! simular problem to the above but i have only had mgf vvc for 4 days!!! driving the car today, everthing ok till i turn the heater control to hot...started to blow cold and then after a few minutes the engine temp went to hot...stopped immediately..as expected boliing water was arttempting to spill out of water expansion bottle...left engine to cool down and limped home...car apparently was sitting idle for 6 months before i bought it...its done 50k but had new head gasket etc at 38k so i dont think its the head gasket....any help would be greatly appreciated.

sorry about repeating myself...didnt relaise i had to register first
PM Marks

You can't assume its not the gasket simply because its only done 12000 miles since the last change. Some folk have had a gasket let go after only 3000 miles. It could be simply that the system needs bleeding of air locks.
Mike Howlett

Thank you, bleed system this morning, seems ok...gonna take her out for a spin in a little while so i'll let you know...thanks again...i hope
PM Marks

The MGOC lists a PRT kit to fit TF CVT that should be easy to fit into any F or TF. I made my conversion from a Freelander kit and just cut the hoses to fit.
Jon F

Jon, Thank you, what do you drink? Spoke to Roger Parker @ OC who supplied a new PRT. We made up the rest of the heater and by-pass system using some of the orginal hoses, y-pieces, adaptors and a midget bottom hose (AHA8730). Heater now works everytime. Much relief all round!

William de la Riviere

This thread was discussed between 15/01/2008 and 16/02/2008

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