Overheating

Running temperature is the complaint heard most often from E-Type owners, and it is heard most often in slow traffic on a warm day. The car was developed for a period of lower ambient traffic density and different fuel, and the cooling system has little margin when any one part of it is below par.

What Jaguar itself changed

The factory addressed cooling during the car's life. The Series 2 introduced an enlarged front air intake and twin electric cooling fans, changes that speak to the airflow limits of the earlier cars. A Series 1 in good order can hold its temperature; it has less to spare when something is wrong.

Work through it in order

• Airflow. A radiator core silted or bent flat passes air poorly, and a missing or damaged fan cowl and undertray lets air take the easy route around the core rather than through it.
• The fan and its switch. Confirm the fan actually runs, and that the thermostatic switch closes at all rather than only when the gauge is already high.
• Water flow. A tired water pump, a partly blocked core, a collapsing bottom hose or a thermostat stuck part shut all restrict circulation. A radiator that has never been out is a suspect.
• The mixture of coolant and water, and the cap. A cap that no longer holds pressure lowers the boiling point of the system.
• Ignition timing and mixture. Retarded timing and a weak mixture both put heat into the engine, and both are free to check before anything is bought.
• The gauge itself. Confirm an indicated reading against an independent thermometer before condemning the engine.

Before reaching for a conversion

Aluminium radiators, uprated fans and electric water pumps are widely sold, and some owners are content with them. They are worth considering only after the standard system has been proved sound, because a modern radiator in front of a blocked block, a slipping fan belt or ten degrees of missing advance will disappoint.