MGF overheating but only at low revs (under 2k)

Hi all, 
 
Looking for ideas please.

Since recent work my MGF VVC shows a worrying rise in coolant temperature when the car is idling, not moving.

The recent work was head gasket replacement (second one in four years of concession use), new thermostat and housing, conversion to waterless coolant. All work was done by specialist MG mechanic.

On the move, temp is rock steady, one notch below half on gauge, even with air con running. Idling at traffic lights or in slow city traffic, and with fans switched on (bypassed by previous owner and fixed by my auto electrician) temp starts to rise. If I can get on the move asap the temp returns to normal.

Has anybody else had the same issue and solved it please?

Thank you

Best regards

David L
 

If the fans are working as they should, then it can only be either poor coolant circulation or partially blocked radiator. Air in system, failing water pump, or radiator would be my guess.

You mentioned the fans having been bypassed by the previous owner.........due to that little nugget of information, I'm thinking the problem might a historical one that predates the resent works.
Your water pump may have cavitation damage, therefor lacking efficiency And yes the radiator may be internally blocked (The tubes full of crap). or externally blocked (the heat exchange fins blocked with other crap)
But 1st bleed the cooling system from all 3 bleed points. This is easy to do but must be done in the correct sequence. For how to do it you'll find the process in the workshop manual which is downloadable for free from the library section of this site, or look in the "How To's" section of this site for lots of tips and how to guides also free.
Where are you approximately located, this info may help us find you help locally if you need it.
 

How long ago was the work done by a specialist MG mechanic? Because my first port of call would be that person! But on low revs the water pump isn't pumping as fast as it does when the engine in running at a normal road speed. But take it back to the specialist first.