Working on the old Packard Coupe's electrical system last month has made us eager to start the engine.  With the cooling system already flushed out, we began to button up the engine, making sure each piece was ready to go back on the car.  A cooling system includes the radiator, connecting hoses, water pump, fan, fan belts, thermo-stat and water passages or jackets around the cylinder block and head.  The water is drawn through the running engine from the bottom of the radiator by the water pump circulating through the engine's water jackets, returning through the thermostat and back into the radiator via the upper radiator hose.  The thermostat regulates the tem-perature.  The engine temperature is critical to a good running engine.  It shouldn't be too hot or too cool.  Temperature gauges are very important to make sure the car runs in the safe zone.  For our Packard, it's 180 degrees.  Our car had sat in a barn for 18 years, so we had the radiator rodded out and completely gone over.  It was full of rust!  A clogged radiator or collapsed hose, stuck thermostat, loose fan belt or bad water pump can all result from a car sitting and will definitely overheat the sys-tem.  If all of the above are right, next remove the freeze plugs to check for rust in the block.  Rust is the most common problem of overheating.  I remember years ago being told by an old mechanic that all old cars run hot.  This of course is nonsense.  The overheating can break down the engine oil and cause premature wear of the valves, cylinders, pistons and bearings, and can crack heads.  We always check our water pump impeller.  Many times they are corroded to the point where they do not effectively pump water any more.  If you have a water pump rebuilt, always ask what kind of replacement impeller they use, and does it put out the same volume of water as the original.  Our Packard's impeller looked fine, so we cleaned the pump using a die grinder with wire wheel, and put on a new pump gasket, sealing it with Permatex 2-B, then installing it on the car using a new pump-to-block gasket.  The bottom bolt holes go into the water ports, and if you don't use brake line copper "seal washers", they will leak.  When we originally removed the pump, we noticed where a chunk of metal had been ground off the pump around one of the mounting bolt holes.  This was because when the front rubber engine support wears out, the front of the engine drops down about 1/2" from rubber fatigue.  The remedy here is to jack up the engine and put in a new rubber support.  These are available from Steele Rubber (800-544-8665).  Our thermostat was replaced using a 160 degree.  Original-ly, there was a low tem 151 degree, standard 160 degree, and high temp 180 degree.  We went with the 160.  On the small eight cars, they are held in place with a spring wire, similar to the ones used on Oldsmobiles of that era.  Our car (custom 8) used a retainer sleeve that just slips in the thermostat housing behind the thermostat, to hold it in place.  To test our thermostat, we put it on the stove in a pan full of water, sub-merging the thermostat with a wire attached to its frame, not allowing it to touch the pan.  Since there is no water pressure as there would be on the car, the thermostat will open 8-10 degrees above its rated temperature.  It checked out okay.  It was in-stalled along with new hoses and correct clamps.  When we first go the car, we had replaced the gas line using brake line.  The problem with doing this is that the brake line nuts will screw into the fuel pump flex hose, but the brake line has a square nut instead of the pressure fitting.  This is easily fixed by buying an adapter to fit the two together.  We were now ready for the carburetor.  Ours had already been rebuilt and was ready to go on the car.  It has a special electrical throttle start.  Packard bor-rowed from Buick (1939) on this one.  It is a Bakelite unit with two electrical wires connected, and consists of a throttle linkage, ball bearing, plunger, guide and contact spring.  The car is started by depressing the accelerator.  The throttle shaft moves the ball bearing inside the unit and makes contact with the wires to start the engine.  When the engine starts, vacuum sucks the ball bearing into a vacuum seat to keep the starter from re-engaging while the engine is running.  Most everything is now back on the engine.  We're getting close!  Next month, we'll start the car and use a new tool to help us analyze our newly-running straight 8!  Keep 'em driving!.