Engine Cooling System: Diagnosis Chrysler Voyager IV

VISUAL INSPECTION

If the cooling system problem is not caused by a driving condition, perform a visual inspection to determine if there was a recent service or accident repair, including the following

1. Loose/damaged water pump drive belt
2. Incorrect cooling system refilling (trapped air or low level)
3. Brakes possibly dragging
4. Damaged hoses
5. Loose/damaged hose clamps
6. Damaged/incorrect engine thermostat
7. Damaged cooling fan motor, fan blade and fan shroud
8. Damaged head gasket
9. Damaged water pump
10. Damaged radiator
11. Damaged coolant recovery system
12. Damaged heater core
13. Open/shorted electrical circuits

If the visual inspection reveals none of the above as cause for a cooling system complaint, refer to the following diagnostic charts.

Scheme 16

Scheme 17

Scheme 18

Scheme 19

Refer to (Scheme 21) when using the TEMPERATURE GAUGE INDICATION DIAGNOSIS CHART.

Scheme 20

Scheme 21

INSPECTION

After performing a cleaning/flush procedure, inspect all hoses, clamps and connections for deterioration and leaks. Inspect radiator and heater core for leaks.

DIAGNOSIS AND TESTING - COOLANT CONCENTRATION TESTING

Coolant concentration should be checked when any additional coolant was added to system or after a coolant drain, flush and refill. The coolant mixture offers optimum engine cooling and protection against corrosion when mixed to a freeze point of - 37°C (-34°F) to - 46°C (-50°F). The use of a hydrometer or a refractometer can be used to test coolant concentration.

A hydrometer will test the amount of glycol in a mixture by measuring the specific gravity of the mixture. The higher the concentration of ethylene glycol, the larger the number of balls that will float, and higher the freeze protection (up to a maximum of 60% by volume glycol).

A refractometer (Special Tool 8286) will test the amount of glycol in a coolant mixture by measuring the amount a beam of light bends as it passes through the fluid.

Some coolant manufactures use other types of glycols into their coolant formulations. Propylene glycol is the most common new coolant. However, propylene glycol based coolants do not provide the same freezing protection and corrosion protection and is not recommended.

DIAGNOSIS AND TESTING - COOLANT RECOVERY SYSTEM

The cooling system is closed and designed to maintain coolant level to the top of the radiator.

1. With the engine off and cooling system not under pressure, drain several ounces of coolant from the radiator draincock while observing the coolant recovery container. Coolant level in the container should drop.
2. Remove the radiator pressure cap. The coolant level should be full to the top radiator neck. If not, and the coolant level in the container is at or above the MIN mark, there is an air leak in the coolant recovery system.
3. Check hose and hose connections to the container, radiator filler neck or the pressure cap seal to the radiator filler neck for leaks.

Scheme 22

1. Raise the vehicle on hoist.
2. Remove the lower attaching screws (Scheme 22)
3. Lower the vehicle.
4. Remove the upper attaching screw (Scheme 22)
5. Disconnect recovery hose from container (Scheme 22)
6. Remove the recovery container.

DIAGNOSIS AND TESTING - ENGINE BLOCK HEATER TESTING

If unit does not operate, trouble can be in either the power cord or the heater element. Test power cord for continuity with a 110-volt voltmeter or 110-volt test light; test heater element continuity with an ohmmeter or 12-volt test light.

DIAGNOSIS AND TESTING - ENGINE COOLANT THERMOSTAT

The thermostat is operated by a wax filled chamber (pellet) which is sealed. When heated coolant reaches a predetermined temperature the wax pellet expands enough to overcome the closing spring and water pump pressure, which forces the valve to open. Coolant leakage into the pellet will cause a thermostat to fail open. Do not attempt to free up a thermostat with a screwdriver.

Thermostat diagnostics is included in powertrain control module's (PCM) programing for on-board diagnosis. The malfunction indicator light (MIL) will illuminate and a diagnostic trouble code (DTC) will be set when an "open too soon" condition occurs. Do not change a thermostat for lack of heater performance or temperature gauge position, unless a DTC is present. For other probable causes, (Refer to DIAGNOSIS AND TESTING ). Thermostat failing shut is the normal long term mode of failure, and normally, only on high mileage vehicles. The temperature gauge will indicate this (Refer to DIAGNOSIS AND TESTING ).

Scheme 23

Scheme 24

1. Drain cooling system below the thermostat level. (Refer to «STANDARD PROCEDURE»(ref-338220-S01254302102009081800000) ).
2. Remove radiator upper hose from the coolant outlet housing (Scheme 23)
3. Remove coolant outlet housing bolts and housing (Scheme 24)
4. Remove thermostat. Discard gasket and clean both gasket sealing surfaces.

DIAGNOSIS AND TESTING - COOLING SYSTEM PRESSURE CAP TESTING

Dip the pressure cap in water. Clean any deposits off the vent valve or its seat and apply cap to end of the Pressure Cap Test Adaptor that is included with the Cooling System Tester 7700 (Scheme 25) Working the plunger, bring the pressure to 104 kPa (15 psi) on the gauge. If the pressure cap fails to hold pressure of at least 97 kPa (14 psi), replace the pressure cap.

Scheme 25

If the pressure cap tests properly while positioned on Cooling System Tester (Scheme 25), but will not hold pressure or vacuum when positioned on the filler neck. Inspect the filler neck and cap top gasket for irregularities that may prevent the cap from sealing properly.

DIAGNOSIS AND TESTING - RADIATOR CAP TO FILLER NECK SEAL

The pressure cap upper gasket (seal) pressure relief can be checked by removing the overflow hose at the radiator filler neck nipple (Scheme 26) Attach the Radiator Pressure Tool to the filler neck nipple and pump air into the radiator. Pressure cap upper gasket should relieve at 69-124 kPa (10-18 psi) and hold pressure at 55 kPa (8 psi) minimum.

Scheme 26

There is no need to remove the radiator cap at any time except for the following purposes

1. Check and adjust coolant freeze point.
2. Refill system with new coolant.
3. Conducting service procedures.
4. Checking for vacuum leaks.

Hold the cap in your hand, top side up (Scheme 27) The vent valve at the bottom of the cap should open. If the rubber gasket has swollen, preventing the valve from opening, replace the cap.

Scheme 27

Hold the cleaned cap in your hand, upside down. If any light can be seen between vent valve and the rubber gasket, replace the cap. Do not use a replacement cap that has a spring to hold the vent shut.

A replacement cap must be of the type designed for coolant reserve systems. This design ensures coolant return to the radiator.

Replace water pump body assembly if it has any of these defects

1. Cracks or damage on the body.
2. Coolant leaks from the shaft seal, evident by wet coolant traces on the pump body.
3. Loose or rough turning bearing.
4. Impeller rubs either the pump body or the engine block.
5. Impeller loose or damaged.
6. Sprocket or sprocket flange loose or damaged.

Replace the water pump if it has any of the following defects.

Scheme 28

1. Damage or cracks on the pump body.
2. Coolant leaks; this will be evident by a wet stream of coolant running down the pump body and components below. A thin stain below the weep hole reservoir slot see scheme 37 is considered normal operation.
3. Impeller rubs inside of chain case cover.
4. Excessively loose or rough turning bearing.

Note. A weepage stain that is black, brown, or grey is considered normal, if it is dry. If the weep appears wet; pressure test the cooling system at 15-18 psi and observe the weep area. If weep area remains unchanged, do not replace the water pump for this condition. Replace the water pump, if a steady flow of engine coolant is evident from the weep hole/reservoir slot see scheme 37 (shaft seal failure). Be sure to perform a thorough analysis before replacing water pump.

Scheme 29

1. Install new seal into water pump housing groove see scheme 38
2. Position the water pump pulley loosely between pump housing and drive hub (Scheme 28)
3. Install water pump and pulley to the timing chain case cover see scheme 34 Tighten water pump bolts to 12 N.m (105 in. lbs.).
4. Position pulley on water pump hub. Install bolts and tighten to 28 N.m (250 in. lbs.) see scheme 34
5. Rotate pump by hand to check for freedom of movement.
6. Install the accessory drive belt. (Refer to «INSTALLATION»(ref-338220-S02643625932009081800000) ).
7. Install drive belt shield.
8. Fill the cooling system. (Refer to «STANDARD PROCEDURE»(ref-338220-S01254302102009081800000) ).