As mentioned before, Head Gasket Failures (HGFs) are attributable to an unfavourable temperature gradient either side of the thermostat, this is due in the most part to overcooling via the long radiator run.

This is not a new phenomenon but has been experienced in just about every mid-engined car.

There are three possible modifications that one can make:

1. Install a remote thermostat
2. Drill the thermostat ring to allow coolant flow, even through a closed thermostat
3. Install a temperature and pressure sensitive thermostat.

1. The remote thermostat

The remote thermostat solution was first implemented in the 1980s on the Ford RS200 rally car, which had a mid-mounted Cosworth BDT turbo producing upward of 400BHP. The cycling effect in the cooling system destroyed a few engines before Hart moved the thermostat to a remote location. This has been common practice on many mid-engined cars since.

Simon Scuffham was one of the trail-blazers for this particular modification based on his Elise-racing experience. Read a description of his modification here. Carl's remote thermostat solution, based on Simon's original description, can be found here. Dave Monk undertook a very similar modification on his MGF as well, and undertook telemetry measurements to record its efficacy. Read more about this here.

2. The drilled thermostat

This solution was highlighted by friends and competitors in the MGCC MGF Cup series. Because of the remote nature of the radiator causing larger than 'normal' [compared to FWD applications] changes in coolant temperature entering the engine causing thermal cycling. This phenomena was found to be significantly damped by drilling small holes in the thermostat ring.

Drilling the thermostat does lessen the cycling problem to an extent (and is data available, captured from thermo-couples in the cooling system, to show its effectiveness). It is not a complete solution however.

For Dieter's drilled thermostat directions, click here.

3. Temperature and pressure sensitive thermostat

The pressure relief thermostat, the PRT, was MG Rover's own solution to the limitations found on the cooling system fitted to the MGF. More remotely mounted, and now found on the "outlet" side of the engine, the thermostat would also open to permit flow under high pressure - as found when the engine speeds were high, and the thermostat still closed (revving a cold engine!). Read more about the PRT here.