A little more noodling as I try to understand what’s happening. I lightly greased the piston and bore, then temporarily reassembled the WRD. Repeated the hot water test, this time for the whole assembly rather than just the temperature sensing cell. Got similar results. Extension is from shaft end to shoulder (where the shaft emerges from the housing). Obviously the temperature of the part lags the water temperature, but this gives a sense of what’s happening.
Temp F Extension (mm)
80 8.6
90 8.6
100 8.6
110 8.6
120 9.5
130 9.9
140 10.2
150 10.6
160 10.9
170 11.2
———————————80C (176F) thermostat temperature
180 11.7
190 12.3
200 12.9
210 13.4
I was mistaken- the shaft to the fuel pump does not get full extension (15.8mm) at maximum temperature, though I confirmed the air passage was closed at max temp.
The nose of the WRD protrudes 14.0mm into the injection pump. The lever inside the injection pump rests 14.4mm inside, and at full travel is at 29.0mm from the mounting plane of the WRD. Which means that at 80F the lever inside the pump should be moved by (14.0 + 8.6) - 14.4 = 8.2mm
At thermostat temperature, injection pump arm is moved by (14.4 + 11.5) - 14.4 = 11.3mm. Lots of room to go further (29 - 11.3 = 17.7mm)!
I reassembled the WRD wet section with some Hylomar to ensure the water seal of the temperature cell. I have not reinstalled it yet.
Corrections?
What next?
