SECTION 6s

ENGINE -COOLING SYSTEM

The cooling system is designed with two purposes in mind; first, to carry off a certain amount of the heat created in the engine so it will not operate at too high a temperature; and second, to maintain the engine heat at the temperature which will produce the most efficient and economical operation of the engine.

The water pump (fig. 1 and fig. 2) is the ball bearing, centrifugal vane impeller type. It requires no care other than to make certain the air vent at the top of the housing and the drain holes in the bottom do not become plugged with dirt or grease.

The drive shaft and the double row ball bearing are integral. The bearing is packed with a special high melting point grease at the time of manufacture and requires no further lubrication. The ends of the bearing are sealed to retain the lubricant and prevent dust and dirt from entering. The outside diameter of the bearing is a press fit in the housing.

The pump shaft seal, a combination rubber and plastic design, is retained in the housing by a metal seal housing, pressed into the pump body. A coil spring mounted inside, and an integral part of the seal, maintains a constant pressure against the thrust washer and rotor, assuring a positive seat. An air vent in the top of the housing and drain holes in the bottom, prevent any water seepage past the thrust washer from entering the bearing.

All fans are of the four blade type with blades spaced so as to dampen out vibrations and of a size to provide adequate cooling. The fan blade and the water pump pulley are bolted to a fan hub, pressed on the pump shaft. The pulley is driven from the crankshaft pulley by means of a "V" type endless fan belt.

The thermostat, mounted in the cylinder head water outlet, restricts the flow of water to the radiator until a predetermined temperature is reached, thus minimizing the length of time required to reach efficient operating temperature.

A water by-pass is included in the cooling system, utilizing a hole in the cylinder block. This allows a limited circulation of coolant, by-passing the thermostat, until thermostat opening temperatures are reached. This system provides a uniform coolant temperature throughout the engine, eliminating localized hot-spots and improving exhaust valve life. It also provides fast warm-up of lubricating oil and fast temperature rise in the coolant which provides fast heater operation in cold weather.

A pressure cooling system is provided for on all models by a pressure type radiator cap (fig. 3). The pressure type radiator cap used is designed to hold a pressure up to approximately seven pounds per square inch above atmospheric pressure in the cooling system. Above seven pounds the pressure is relieved by a valve within the cap that opens to radiator overflow. As the pressure is reduced to atmospheric upon cooling a "reverse" valve in the cap allows air to re-enter the radiator, preventing the formation of a vacuum in the cooling system.

The pressure type radiator cap helps to prevent coolant loss from boiling, for by raising the pressure on the coolant above atmospheric, the coolant will not boil until a higher temperature is reached, approximately 222°F. for water. This increases the margin of safety between the coolant operating temperature and the boiling point, and is advantageous in that it permits the engine to operate at higher temperature without having the coolant overflowing. Thus, vehicles may operate at slightly higher engine temperatures, and may do so with a minimum of coolant loss from

Since the action of the cooling system controls the operating temperature of the engine, it is essential that systematic inspection of units in the system be made periodically to maintain the efficiency of the system.

In the course of engine operation, rust and scale accumulate in the radiator and engine water jacket. These accumulations may materially reduce the efficiency of the cooling system and will be reflected in the engine operation. The speed of accumulation is influenced by the kind of daily engine operation, engine condition and the type of water (hard or soft) used in the cooling system. The accumulation of these deposits can be kept to a minimum by the use of a good rust inhibitor, but it should be remembered that an inhibitor will not remove rust already present in the cooling system.

Following are a few checks and tests which will give an indication of cooling system failures.

1. Test for restriction in the radiator, by warming the engine up and then turning the engine off and feeling the radiator. The radiator should be hot at the top and warm at the bottom, with an even temperature rise from bottom to top. Cold spots in the radiator indicate clogged sections.
2. Water pump operation may be checked by running the engine while squeezing the upper radiator hose. A pressure surge should be felt.
3. A defective head gasket may allow exhaust gases to leak into the cooling system. This is particularly damaging to the cooling system as the gases combine with the water to form acids which are particularly harmful to the radiator and engine. To check for exhaust leaks into the cooling system, drain the system until the water level stands just above the top of the cylinder head, disconnect the upper radiator hose, and remove the thermostat and fan belt. Start the engine and quickly accelerate several times. At the same time note any appreciable water rise or the appearance of bubble which is indicative of exhaust gases leaking into the cooling system.

In selecting an antifreeze solution for winter operation, the local conditions and the type of service must be considered. In any event, it is very essential to make certain checks and do certain things to at least insure the antifreeze remaining in the cooling system. To be certain that the solution will not leak out and be lost entirely, resulting in little or no protection against freezing, or seep into the working parts of the engine, the following procedure should be followed in conditioning the system.

1. Drain the entire cooling system including the cylinder block. NOTE: If considerable rust, scale, oil or grease is present in the water drained out, it is advisable to flush and clean the system.
2. Tighten all cylinder head bolts in sequence as shown in the Engine Section of this manual.
3. Check the water pump for leaks, excessive end play or looseness of the shaft in the Pump. NOTE: Should the water pump leak or indicate that leakage would occur with antifreeze in the system, it should be repaired, see "Major Service Operations, Water Pump."
4. Inspect fan belt. Replace if badly worn. Adjust belt to proper tension.
5. Inspect all radiator and heater hoses. If hoses are collapsed, cracked or in any way indicate a rotted condition on the inside, replacement should be made. Carefully check and tighten all hose clamps.
6. Check the thermostat. Make sure it does not stick open or closed.
7. Fill the cooling system with the proper quantity of antifreeze and water according to instructions of manufacturer of antifreeze. NOTE: Be sure to allow for additional amount of antifreeze solution when vehicle is equipped with a hot water heater.
8. Warm up engine and recheck radiator, water pump and all hose connections for leaks with ENGINE HOT.
9. Check and adjust valves when necessary. See "Engine Section." NOTE: Tightening of cylinder head bolts will affect valve clearance adjustment.

1. Loosen bolt at generator slotted bracket.
2. Pull generator away from engine until desired belt tension is obtained. NOTE: With light pressure applied midway between the water pump pulley and the generator pulley, the belt should deflect 5/16" on 6 cylinder engine models, 13/16" on V-8 engine models (fig. 4).
3. Tighten all generator bolts securely.

THERMOSTAT

The thermostat consists of a restriction valve actuated by a thermostatic element. This is mounted in the housing at the cylinder head water outlet above the water pump.

Thermostats are designed to open and close at predetermined temperatures and if not operating properly should be removed and tested.

1. Remove radiator to water outlet hose and remove gas line clip from water outlet on 6 cylinder models.
2. Remove water outlet to thermostat housing bolts and remove water outlet, gasket and
3. Inspect thermostat bellows and valve to make sure they are in good condition.
4. Place thermostat in hot water 25° above the temperature stamped on the thermostat valve.
5. Submerge the bellows completely and agitate the water thoroughly. Under this condition the valve should open fully.
6. Remove the thermostat and place in water 10° below temperature indicated on the valve.
7. With bellows completely submerged and water agitated thoroughly, the valve should close completely.
8. If thermostat checks satisfactorily, replace, using a new housing gasket.

Unless water in the cooling system is treated with a corrosion preventive, rust and scale may eventually clog water passages in the radiator and water jackets. This rust accumulation will result in inefficient operation of the cooling system, vitally affecting engine performance and economy of operation.

Two common causes of corrosion are: (1) air suction-air may be drawn into the system due to low liquid level in the radiator, leaky water pump or loose hose connections; (2) exhaust gas leakage -exhaust gas may be blown into the cooling system past the cylinder head gasket or through cracks in the cylinder head and block.

Periodic service must be performed to the engine cooling system to keep it in efficient operating condition. These services should include a complete cleaning and reverse flushing as well as a reconditioning service as explained under "Antifreeze."

Cleaning

A good cleaning solution should be used to loosen the rust and scale before reverse flushing the cooling system. There are a number of cleaning solutions available and the manufacturer's instructions with the particular cleaner being used should always be followed.

An excellent preparation to use for this purpose is G.M. Cooling System Cleaner. The following directions for cleaning the system applies only when this type cleaner is used.

1. Drain the cooling system including the cylinder block and then close both drain cocks. On eight cylinder models, replace pipe plugs on each side of block.
2. Remove thermostat and replace thermostat housing Fig. 5.
3. Add the liquid portion (No. 1) of the cooling system cleaner.
4. Fill the cooling system with water to a level of about 3 inches below the top of the overflow pipe.
5. Cover the radiator and run the engine at moderate speed until the heat indicator reaches 180 degrees.
6. Remove cover from radiator and continue to run the engine for 20 minutes. AVOID BOILING.
7. While the engine is still running, add the powder portion (No. 2) of the cooling system cleaner and continue to run the engine for 10 minutes.
8. At the end of this time, stop the engine, wait a few minutes and then open the drain cocks and lower hose connections. CAUTION: Be careful not to scald your hands.

Reverse Flushing

Reverse flushing should always be accomplished after the system is thoroughly cleaned as outlined above. Flushing is accomplished through the system in a direction opposite to the normal flow. This action causes the water to get behind the corrosion deposits and force them out.

Radiator

1. Remove the upper and lower radiator hoses and replace the radiator cap.
2. Attach a lead-away hose at the top of the radiator.
3. Attach a new piece of hose to the radiator outlet connection and insert the flushing gun in this hose.
4. Connect the water hose of the flushing gun to a water outlet and the air hose to an air line.
5. Turn on the water and when the radiator is full, turn on the air in short blasts, allowing the radiator to fill between blasts of air. CAUTION: Apply air gradually as a clogged radiator will stand only a limited pressure.
6. Continue this flushing until the water from the lead-away hose runs clear. NOTE: If Powerglide model radiators are to be tank tested for repairs, plug oil cooler openings tightly.

Cylinder Block and Cylinder Head

1. With thermostat removed, attach a lead-away hose to the water pump inlet and a length of new hose to the water outlet connection at the top of the engine.
2. Insert the flushing gun in the new hose.
3. Turn on the water and when the engine water jacket is full turn on the air in short blasts.
4. Continue this flushing until the water from the lead-away hose runs clear.

Hot Water Heater

1. Remove water outlet hose from heater core pipe.
2. Remove inlet hose from engine connection.
3. Insert flushing gun and flush heater core.

Care must be taken when applying air pressure to prevent damage to the core.

After cooling system has been cleaned and reverse flushed, the system should be thoroughly reconditioned. Procedure for reconditioning as outlined under "Antifreeze" in this section should be followed.

Dirt and bugs may be cleaned out of the radiator air passages by blowing out with air pressure from the back of the core.

Water Pump

The water pumps on both 6 and 8 cylinder models are basically similar, and are both covered in the same operation description.

Removal and Disassembly

1. Drain radiator and remove water inlet hose from pump. Remove fan belt.
2. On heater equipped models, remove hose from pump housing.
3. Remove water pump to cylinder block attaching bolts and remove pump from engine. CAUTION: On 6 cylinder models, pull pump straight out of cylinder block to avoid damage to impeller and shaft.
4. Remove fan and pulley by removing four retaining bolts.
5. On 8 cylinder models, remove back plate screws, plate and gasket.
6. Support fan hub in an arbor press and press pump shaft out of hub. A 1/2" x 2" bar will allow the shaft to be pushed through the hub. See fig. 6.
7. Support pump in an arbor press on the face that attaches to the cylinder block. Press shaft and impeller assembly out of pump, applying pressure on the outer race of the shaft bearing only (fig. 7). CAUTION: Shaft and bearing assembly must not be pushed out of housing by applying force on shaft, or bearings will be damaged. Use a 7/8" deep socket or piece of tubing 1 1/8" O.D. Shaft and bearing assembly should be pressed out of rear of pump only.
8. Support impeller on seal surface, using Press Plate J-5855, Generator Bearing Remover and Installer, in an arbor press, and, using a 1/2" x 2" pin, press shaft out of impeller (fig. 8). Discard seal.

1. Wash all parts except pump shaft bearing in cleaning solvent. ( fig 9 and fig 10) show the water pumps disassembled. NOTE: Pump shaft bearing is a permanently sealed and lubricated bearing and should not be washed in cleaning solvent.
2. Inspect shaft and bearing assembly for roughness or excessive end play. Remove any rust or scale from shaft with fine emery cloth. The bearing should be wrapped in cloth while this operation is performed to prevent emery dust from entering bearing.
3. Inspect seat for thrust washer on impeller for pit marks or scoring. If seat for thrust washer is scored or pitted, the impeller should be replaced.

Assembly and Installation

1. Install pump shaft and bearing assembly into pump body bearing bore, applying pressure to outer race until it is flush with front of pump body (fig. 11). CAUTION: Apply pressure to outer race only.
2. Lightly coat O.D. of new seal with a sealing compound and press into place with tool J-5590 Transmission Front Bearing Installing Tool, applying pressure to the seal outer flange. The seal should bottom with the outer flange against the pump body ( fig. 12).
3. Press on fan hub. Check fan hub location, as this is very critical and has a definite bearing on fan belt operation. Install gauge J-5775 in one of the bolt holes, from rear of pump (fig. 13). Place a straight edge on the front face of the fan hub with the head of the gauge held firmly against body, straight edge should lightly contact short step on gauge for 6 cylinder models, end of gauge for 8 cylinder models (fig. 14). NOTE: The factory specification on this dimension carries a tolerance of ±.005°.
4. Support pump on front or hub end of shaft and press on impeller. Press to obtain .010" to .035" clearance between impeller vanes and pump body. On eight cylinder models, it will be necessary to put a bend about 1/2" from end of feeler gauge to enable clearance checking (fig. 15).
5. Install pump pulley and fan on pump hub and tighten bolts securely.
6. Install pump assembly on cylinder block and tighten bolts securely. Use a new pump to block gasket.
7. Install hoses and fill cooling system.
8. Install fan belt and adjust for 5/16" deflection with a light load applied at point midway between fan pulley and generator pulley on 6 cylinder models, and 13/16" on 8 cylinder models.
9. Check and adjust radiator core to fan clearance. This should be 5/8" to 3/4" at the point of minimum clearance. This adjustment is made by loosening core to core support bolts, moving core and tightening bolts.
10. Start engine and check for leaks.

1. Remove drain plug and drain radiator.
2. Remove radiator to water outlet hose.
3. Remove radiator to inlet pipe hose.
4. On models equipped with Powerglide automatic transmission, remove oil cooler lines from radiator and plug lines and radiator fittings.
5. Remove radiator core to radiator support bolts and lift radiator core straight up to remove.
6. Slide radiator core into position.
7. Install radiator core to radiator support bolts, adding spacer shims as required. Adjust radiator core to fan blade clearance, 5/8" to 3/4" at point of minimum clearance.
8. Install radiator hoses and replace radiator drain plug.
9. Install cooler lines on Powerglide models.
10. Fill cooling system and check for leaks.

Cooling System Capacity

All models without heater - 16Qt.
(Add 1 quart for any model with heater.)

Water Pump

Type and drive - Centrifugal by fan belt
Location - Front of cylinder block
Capacity - 6 cylinder, 55 gal. per minute at 4000 RPM engine speed.
Capacity - 8 cylinder, 44.5 gal. per minute at 4000 RPM engine speed.
Impeller Location - 6 cylinder-cyl. block
Impeller Location - 8 cylinder-pump body
Bearings - Permanently lubricated and sealed ball.
Seal - Molded rubber and fiber, automatically spring adjusted.

Fan

Diameter - 17"
Number of Blades - 4
Fan to Engine Speed Ratio - .95:1

Fan Belt

Adjustment - Movable generator
Deflection - Light load midway between generator pulley and fan pulley.
Deflection - 6 cylinder - 5/16"
Deflection - 8 cylinder - 13/16"
Thermostat - Normal rating 160°F. Starts to open 157°-163°. Fully open 183°F.
Location - 6 cylinder head water outlet
Location - 8 cylinder intake manifold water outlet

Radiator Core

Make and Type - Harrison, Ribbed Cellular
Frontal Area
6 cyl.

Troubles and Remedies

Cooling System

Symptom and Probable Cause
Probable Remedy

Overheating

a. Lack of coolant
a. Refill system and check for leaks

b. Fan belt loose
b. Adjust

c. Fan belt oil soaked
c. Replace fan belt

d. Thermostat sticks closed
d. Replace thermostat

e. Water pump inoperative
e. Repair or replace water pump

f. Cooling system clogged
f. Clean system and reverse flush

g. Incorrect ignition timing
g. Retime engine

h. Brakes dragging severely
h. Adjust brakes

Overcooling

a. Thermostat remains open
a. Replace thermostat

b. Extremely cold climate
b. Cover part of radiator area

Loss of Coolant

a. Leaking radiator
a. Replace or repair

b. Loose or damaged hose connection
b. Tighten or replace hose connections

c. Leaking water pump
c. Repair water pump

d. Loose or damaged heater hose
d. Tighten or replace hose

e. Leaking heater unit
e. Replace or repair beater core

f. Leak at cylinder head gasket
f. Replace gasket and tighten bolts securely and evenly

g. Cracked cylinder head
g. Replace cylinder head

h. Cracked cylinder or block expansion plug loose
h. Make necessary repairs or replacements

i. Engine operating at too high temperature
i. See overheating causes

Circulation System Noisy

a. Pump bearing rough
a. Replace pump

b. Fan blades loose or bent
b. Tighten or replace fan blades

c. Fan belt noisy in pulley
c. Dress with belt dressing or soap and adjust

d. Fan belt inner plies loose
d. Replace fan belt

e. Improper fan to radiator clearance
e. Adjust clearance, 5/8" to 3/4"