I just opened my coolant tank reservoir and dipped my finger in the coolant and smelled it. It smells pretty nasty and old. What is the procedure for draining the coolant? Is it as simple as removing the drain plug, plugging it back in and refilling?

 

If you have the factory manual, check to see what procedure is recommended. The system has essentially two drains: one at the lower corner of the radiator and one on the engine block. I believe the one on the block is on the LH side, but my memory isn't what it used to be!

NBCat

 

What is the difference between "HE" and "non-HE" models? This is the terminology used in the FSM.

 

The term 'HE', as used by Jaguar, refers to the V12 engined XJ-S and Series III models with a revised cylinder head having 'High Efficiency' output due to the shape of the combustion chambers. Is your car a Series III XJ12?

NBCat

 

There is no particular technique needed for re-filling the six cylinder XK engine, apart from making sure the heater valve is open when filling. When I did it, I used to fill to the top where the blanking cap fits, put it on, start the engine and rev up a few times, (engine only warm, never hot), then take cap off and top up. There needs to be a pint or two of coolant put into the expansion tank too.

Draining involves the drain plug at left rear of the block, down near to where the cylinder head oil feed pipe is located. Earlier cars had a little tap, but eventually this was dropped, because it blocked up. Even taking out the plug may still require poking around with a bit of wire to loosen up the crud. I don't think there is a separate drain on the radiator, you have to take off the bottom hose, but I may be wrong on this one.

The V12s have bleed valves in certain places to use while filling.