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MOTRS

MGF / MG TF

1995-2011 / Roadster / United Kingdom

All MGF / MG TF problems All workshop problems
Minor Cooling System Issues

Thermostat Failure

Symptoms

The engine overheats, particularly at sustained speeds. Alternatively, the engine never reaches operating temperature (thermostat stuck open), which causes poor fuel economy and increased wear.

Cause

The thermostat sticks -- either closed (causing overheating) or open (causing under-temperature running). The wax pellet mechanism degrades over time.

Fix

Replace the thermostat ($20--40 AUD).

Use an 82-degree unit.

Some owners fit an 88-degree thermostat for Australian conditions, but the consensus in the community is that 82 degrees provides better thermal headroom and reduces the risk of head gasket stress.

Replace every 5 years as preventive maintenance.

Cost mentioned in fix
$20

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// More MGF / MG TF problems

Other known issues

Critical Cooling System Issues

Expansion Tank Cracking

Coolant weeps or sprays from a crack in the plastic expansion tank. The tank may split suddenly under pressure, dumping all the coolant. Coolant level drops with no apparent engine fault.
Critical Cooling System Issues

Water Pump Failure

Coolant leak from the pump weep hole. Bearing noise (grinding or whining) from the pump area. Overheating from reduced coolant flow if the impeller corrodes or the bearing seizes.
Critical Cooling System Issues

Coolant Hose Deterioration

Coolant leaks from split or perished hoses. Hoses feel soft, swollen, or show surface cracking.
Minor Cooling System Issues

Air Locks After Coolant Work

After any work that opens the cooling system, the engine overheats despite the system being full of coolant. The heater blows cold air. Temperature gauge spikes erratically.
Minor Head Gasket Failure (K-Series Engine)

What Happens
Minor Head Gasket Failure (K-Series Engine)

Why It Happens
All MGF / MG TF problems