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Jaguar Repair/'72 e type V12 thermostatic vacuum sending unit


4 ports on the thermostatic vacuum sending unit- M port vacuum lines to bypass valves on all carbs and intake manifold. C port to bottom of carb on drivers side. D port to vacuum advance module on dist. Where does F port go ? Are the other 3 ports in the correct spot ?

Where does the vacuum lines on the air cleaners go ?

Thank you for your time,

Hi Richard,

Sorry it took so long. I had to dig through old data to locate any info on the 4 port temp switch.

From what I can find the ports are labeled "C", "D", "MT" and "F-1" on the 4 port switch.  

"C" goes to the intake vacuum side of a solenoid valve which also connects to a ported vacuum port on the carburetors.

"D" goes to the distributor vacuum retard unit,

"M-T" goes to the air filter.

The only data I found on "F-1" is that in a test procedure for the 4 port switch, it says that when the coolant reaches 220 deg F. that "D" is open to "F-1" and "M-T". This implies that vacuum to the distributor is dumped to outside air when the coolant reaches 220 Deg F.

I have not found anything showing where "F-1" goes to. (possibly dumping EGR vacuum too ?)
I do have a test procedure for the 4 port valve if you want it. let me know.


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Howard M. Fitzcharles III


Jaguar from the XK 120 to XJ-6 ser. 3 1987


Dealership line mechanic on MG, Triumph, Jaguar for 15 years, Instructor in commercial mechanics school 2 yr. Product information manager for piston and valve manufacture, Instructor & hotline answer man for import car parts importer 15 yrs.

Associate member SAE EAA member

Import Car magazine

ASE Master Auto with L-1 certification up to 2000

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