We adjusted the carbs to bring the idle down a little and had to do little else for the engine to run smooth and sweet. I decided to clean up the engine compartment a little and got after some of the peeling paint on the exterior of the cooling head tank for the radiator – which is separate from the radiator and located a little aft.  In doings so I discovered a big problem waiting to jump up and bite the owner hard!  The filler neck on the tank was rotten almost all the way through under the pressure cap and just waiting to pop off and blast the coolant out of the system and all over the engine compartment. Clearly this is something to keep an eye out for on these cars.

Location of coolant tank on E-type Series III.

Jaguar Series III radiator tank with rotten filler stem waiting to cause trouble!

New tanks are not that expensive so we got a new one from XKs Unlimited and installed that in the car.  I was really glad to have caught that before delivering the car back to the owner!

Old rotten radiator tank and new replacement for Jaguar E_type Series III from XKs Unlimited.