Changing the engine over from the 5Dr to the 3Dr, i noticed this in the engine bay, is it an external thermostat and is it worth keeping?

yes and yes

Many thanks!

What do I need to do to prep the engine?

if you are going to keep it make sure the old one has been taken out of the engine

That's the 'grey' Pressure Relief Thermostat (PRT) which opens at 82 oC and has the 'light spring',
- Cream is 88° With hard Spring [Designed for Diesel and V8 applications]
- Black is 82° With Hard Spring (Designed for a V8 and used as a stopgap with K4 engines)

Not forgetting the remote thermostat is now available (Black housing IIRC), which is the standard old stat now at the front of the engine, with additional small bypass pipe.


As mentioned already, you need to remove the old stat at the back of the engine and replace with a blanking ring (PEL 000040) but at around £12-14 each
I would butcher the OE stat by drilling / grinding off the 4 welds, remove centre wax expansion bulb and refit the outer ring and rubber seal.

Thank you Northern irelander, I'll do the modification to the thermostat today.