[Early_S_Man]

Guys,

There is supposed to be an 'Insulating Piece,' pn 901.110.925.00, between the thermostat housing and the body of the injection pump. There is a replaceable bushing for the themostat shaft rod, and wear of the bushing, or on the rod could cause inconsistent results of the injection pump mixture.

I suggest conducting some measurements and tests to establish baseline characteristics for the thermostat assembly:

Required tools:

1. Digital Multimeter with temperature capability and Type-K Bead Thermocouple Probe for fast measurement response time (Sears sells a DMM with included bead probe for $59.95 ... another DMM model with Type-K temp. capability and serial port and PC cable, and data logging software, but no probe is $99.95, separate bead probe -- $14.95)

2. Dial caliper with depth-measuring capability or dial indicator and holder

3. Heat Shrink Gun or Hair Dryer ... with adapted hose assembly to fit snugly on thermostat housing ... locally fabricated

Tests:

1. On fully warmed-up engine with oil temp. reading of 180° F, measure the temperature of the bimetallic disks by direct contact of a bead probe into the hot air exhaust of the thermostat assembly.


2. Remove the thermostat assembly from the injection pump, and cover the pump where the thermostat mounts with duct tape.

3. Allow thermostat assembly to cool to room temperature.

4. Draw three tables with columns for temperature and shaft extension ... labeled Test 1, 2, 3.

5. Measure bimetallic disk springs' temperature to establish room temperature baseline within 5° F. Record Room temperature reading at disk 'stack' for Test 1.

With dial caliper depth-measuerement probe, measure shaft extension past base of thermostat housing, and record the extension reading at room temperature row of Test 1.

6. Connect adapter hose from hot air source and turn on to lowest heat setting -- so the heat rise is slow enough to measure at 25° F intervals ... extend hose from heat source if temp rise is too quick!

7. At approximate 25° F intervals, measure temperature and shaft rod extension distance and record on chart for Test 1. Repeat measurements until disk assembly temperature exceeds measured maximum temp on engine after oil was warmed up.

Repeat Tests 2 and 3, then enter data into spreadsheet, and plot X-Y graph with all 3 sets of data. The best results that could be expected would be a perfectly linear curve, and extremely close correlation between all 3 sets of teat data! Do linear regression on the data with temperature as the independent variable, and extension distance as the dependent variable ... then compare the regression data to test data curves.