So the 1994 car where I am working on the cylinder head has a leaking heater control valve. I just discovered after calling one of the main parts importer/suppliers that these valves are unique to the 1993 - 1994 cars and they are no longer available at all. This applies to all cars that have the oil filler cap in the actual cam cover instead of in the separate vertical tube that comes up from the side of the engine used in the pre-1993 cars.
These valves look like the ones shown in the following photos


Heater control valve as installed on the engine


Corroded heater control valve showing nut & olive that screws and seals in fitting on the cylinder head


Fitting located in the rear left hand corner of the cylinder head The nut on the heater control vale screws into the nut in the cylinder head and seals with the olive or ferrule.

The earlier heater control valves look like this and are still available.


Pre-1993 heater control valve

 

I have only seen the cam cover oil fill cap on 1994 MY XJ40's. My '93 had the tube with metal screw-on cap.

 

Hi Steve,

Larry learned the same thing while dealing with a leak on his '94. See his innovative solution at his thread:

https://www.jaguarforums.com/forum/x...ol-tub-216062/

By the way, our '93 VDP had the same heater control valve, but it also had the older-style separate oil fill tube alongside the engine, so it wasn't just the cam-cover oil filler cars that had those valves that connected directly to the cylinder head.

Cheers,

Don

 

Don, thanks for the pointer to Larry's thread on this same subject.
I ordered the early heater control valve, a new nut, and the olive/ferrule from my supplier and I will see what I can figure out for a solution.
When all this stuff shows up, I will take photos of the parts that are still available.