In this months DOC, I will conclude a three-part series on Packard's Electromatic Clutch.  In Part I, I covered Troubles and Corrections.  In Part II, Components, and in Part III, we will examine Electrical Tests and Servicing Procedures.  If you missed Parts I & II, just visit our Archives at

                         ELECTROMATIC ELECTRICAL TESTS:

        The best way to locate a faulty switch or a faulty solenoid is to use a six-volt test lamp.  Any electrical test would be worthless if the circuit is dead, so before you start, be sure to check the fuse which is located between the ignition switch and the Electromatic lockout switch in the main feed cable.

         Lockout Switch:   Disconnect the red lead from the lockout solenoid, clip one test lamp lead to this disconnected wire, then ground the other test lamp lead.  (Figure 1)  When the ignition switch and the lockout switch are both closed, the test bulb should light.

 Lockout Solenoid:   Disconnect both leads from the lockout solenoid terminal and ground one terminal with a jumper wire.  Clip one test lamp lead to the remaining terminal, the other to the ungrounded (negative) battery post as shown in Figure 2.  If the test bulb lights, the solenoid is operating properly.

         Governor Switch:   Disconnect both the ECand the ADwires at their connectors.  Clip one test lamp lead to the ungrounded (negative) battery post, the other in tern to either of the two disconnected wires (Figure 3).  The test bulb should light when contact is made with the ECline, and should not light when contact is made with the ADline.

         Direct Speed Switch:   Disconnect the lead from the direct speed switch terminal, then clip one test lamp lead to this terminal, the other to the ungrounded (negative) battery post (Figure 4).  Move the gearshift lever to the high gear position.  The test bulb should not light.  Move the gearshift lever toward neutral position.  The test bulb should light just before the gear shifter fork starts out of its detent.

         Accelerator Switch:   Disconnect both leads from the accelerator switch terminals, then ground one terminal with a jumper wire.  Clip one lead of the test lamp to the remaining terminal, the other to the ungrounded (negative) battery post (Figure 5).  The test bulb should be lighted with the accelerator pedal in the released position, and should go out just as the control valve operative lever contacts the engine speed screw when then accelerator pedal is depressed.


         Accelerator and Throttle Linkage:   Satisfactory operation of the Electromatic Clutch demands that the accelerator linkage return to its closed throttle position as quickly as possible after release of the accelerator pedal.  This means that the linkage must operate with a minimum of friction.  Therefore, after cleaning and inspecting for worn-out parts, apply lubricant to all friction surfaces except the valve operating rod.  Any lubricant on the valve operating rod would tend to accumulate particles of dust and dirt, finally gumming up between the rod and its valve guide sleeves, so this part must be kept clean and dry of lubricant.

         Control Valve Air Cleaner:   This unit filters air to the clutch control valve through cotton waste and should not be oiled or washed.  Since the cotton element is not replaceable, discard the entire unit and replace it with a new one if it should become clogged with an accumulation of dirt.

         Hose and Steel Lines:   Replace and deteriorated, collapsed or damaged rubber hose and make sure all connections are tight.  Check all tubing connections for tightness and inspect the lines for kinks or breaks.  Replace damaged tubing.

         Power Cylinder:   Check to see that the joint between the two shells of the power cylinder is tight and that the cable connection threads are not stripped.  If the diaphragm has been damaged, replace it with a new one.

         Clutch Control Valve:   Caution!  Clutch control valves are carefully calibrated for the particular models on which they are installed.  Never install a clutch control valve on a model other then that for which it was intended.    If Electromatic Clutch performance remains rough and erratic after all adjustments have been properly made, it is probable that the control valve is at fault.  It should be removed, cleaned, inspected and serviced.  

        To remove the clutch control valve from 22nd Series cars, first disconnect the vacuum lines to the intake manifold and the power cylinder (Figure 6), remove the air cleaner and air inlet line, and disconnect the electrical leads at the lockout solenoid.  The valve may then be removed, leaving the bracket installed on the cylinder head.

        To remove the clutch control valve from 21st Series cars, the following procedure is recommended:  Disconnect the accelerator rod from the valve operating lever, disconnect the throttle rod on the manifold side of the engine.  After removing the cap screws, which attach the control valve bracket to the cylinder head, lift off the control valve and bracket assembly.  Take off the retaining clips and disconnect the control valve operating link rod at the valve operating lever.  Then remove the two cap screws holding the control valve to the bracket and lift off the valve.

        To disassemble the valve, remove the valve operating clevis, remembering to count the number of turns required so that it may be reinstalled to approximately the same position.  Remove the body end cover plate and spring.  Depress the valve piston latch lever and disconnect the slotted link from the fulcrum lever, then remove the valve piston and the slotted link.

        Remove the regulating diaphragm cover and spring, take out the diaphragm, fulcrum lever and valve operating rod as an assembly and remove the gasket and spacer.

        Remove the lockout solenoid, being careful  not to lose the solenoid spring at the bottom of the core.  

        Remove the lockout valve and the solenoid core (Figure 7).  If it is necessary to remove the poppet check valve because of damage to or malfunctioning of this unit, heat the control valve body to a temperature of about 200 degrees Fahrenheit in hot water, then bump the valve body on a wooden block until the poppet valve jars free of the body.

        Clean the control valve body, diaphragm, solenoid core, valve piston, valve operating rod and fulcrum lever with cleaning solvent.

        Wipe the solenoid terminal plate and diaphragm with a clean, solvent-moistened cloth. Do not dip the solenoid nor the diaphragm in cleaning solvent.  Inspect the rubber solenoid valve disc for wear, damage and distortion, and if any of these conditions have occurred, the valve should be discarded and replaced.

        Check the spool valve piston spring, the regulating diaphragm and replace them if necessary.  Inspect the control valve body and working parts for general condition, replacing any parts which have become worn or damaged.  Test the solenoid as described previously in the Testingsection.  

        To reassemble the clutch control valve after the parts have been cleaned and inspected, proceed as follows:

        If the poppet check valve has been removed, or is to be replaced, heat the valve body to about 200 degrees Fahrenheit by dipping it in hot water, and push the poppet valve into position.  Install the solenoid valve and the solenoid core, then install the core spring and the solenoid, tightening all screws evenly.

        Reassemble the diaphragm shaft, fulcrum lever and valve operation rod, and slide this assembly into position in the valve body as a unit.  (Do not lubricate the internal linkage)  Now install the diaphragm spring and cover, tightening all screws evenly.

        Slide the piston-latch lever assembly into position and, holding the latch lever down, snap the slotted link over the center pin in the fulcrum lever (Figure 8).  Using a new gasket, install the body and cover plate and spring.  Install the valve operating rod clevis, using the same number of turns to reassemble the unit as those previously noted when removing it.  Be sure to use a new gasket, then install the assembled control valve on the mounting bracket, then connect the valve operating rod link to the clevis and snap the retaining clip into position.

        I hope this is helpful in keeping your Electromatic Clutch working properly.  They make the car almost effortless to drive, and once they're working, require little maintenance.  Happy New Year, and keep 'em driving!