A worn / poorly installed belt and tensioner or a skewed pulley can cause the belt to slide off.

Doing so can cause the coolant pump and / or fan to slow down and overheat the engine.

The radiator / expansion tank cap is usually the least important consideration when diagnosing engine cooling system problems.

The cooling system uses a sealed radiator cap to prevent the liquid from boiling.

Incorrectly fitting or defective cover can also lead to coolant leakage and overheating of the engine.

Refer to the original equipment documentation for the radiator cap specifications.

Диагностика системы охлаждения Cummins ISF3.8

The air passing through the fins of the radiator due to the vacuum generated by the fan removes heat from the coolant, which is pumped through the radiator by a water pump.

Foreign objects (scraps of paper, dry grass, fabric lint, dust, etc.) can get caught between the ribs, obstructing the passage of air. This will reduce the efficiency of the radiator.

The radiator should be checked periodically for bent or broken fins and coolant leaks.

Диагностика системы охлаждения Cummins ISF3.8

If the fan is belt-driven, belt slippage can reduce fan speed and reduce engine cooling performance.

The problem may also be related to a malfunction of the automatic belt tensioner.

Check the bearings in the fan hub and the rest of the pulleys to make sure they are not causing excessive vibration and belt slippage.

Insulated covers can be used to shorten engine warm-up time and help retain engine heat in cold climates.

Insulating covers should only cover the front part of the radiator, leaving room for air to pass through.

Failure to leave a portion of the front of the radiator open for airflow or remove the thermal covers when the ambient temperature rises can cause the engine to overheat.

If the radiator is combined with a charge air aftercooler, installing the boot without an opening will result in poor charge air cooling.

Do not use homemade cardboard covers. the products of the destruction of such a heater will lead to severe contamination of the radiator and intercooler of the charge air.

Диагностика системы охлаждения Cummins ISF3.8

If the vehicle is equipped with a temperature-controlled louver, check the coolant temperature at which the louver opens and closes.

Compare the result with the value indicated on the blind control.

Cummins recommends opening the louver when the coolant temperature reaches 85 ° C.

Диагностика системы охлаждения Cummins ISF3.8

If the engine is equipped with a temperature-controlled cooling fan clutch, check the coolant temperature at which the fan clutch engages.

Cummins recommends running the fan when the coolant temperature reaches 96 ° C.

If the engine has a viscous fan clutch, check the coolant temperature at which the fan turns on.

Note: some models of viscous fan clutches may be electronically controlled.

If the air temperature reaches a predetermined level, which is determined by the temperature setting of the sensor used, the temperature-sensitive element moves the actuator, which allows the viscous fluid to turn on the fan drive and increase its speed.

Cummins recommends running the fan when the coolant temperature reaches 96 ° C.

Removal and installation of the coolant pump

Диагностика системы охлаждения Cummins ISF3.8

Caution: If there is a persistent coolant leak, replace the coolant pump.

Drain the coolant.

Remove the ancillary drive belt.

Remove the 8 mounting bolts and remove the coolant pump. Tightening torque 8 Nm

Диагностика системы охлаждения Cummins ISF3.8

Clean the surfaces of the coolant pump.

The coolant pump is installed in the reverse order of removal.

Проверка

Make sure the coolant pump impeller is not scored or damaged. If damaged, the impeller must be replaced.

Check the coolant pump seal for damage.

If damaged, the seal must be replaced.

Диагностика системы охлаждения Cummins ISF3.8

Thermostat

Note: The thermostat housing is part of the intake manifold, if the thermostat body is damaged, the intake manifold must be replaced.

Check before removal

After closing the thermostat for 1 minute with the engine running, do the following:

- to monitor the coolant temperature, connect a diagnostic tool.

Диагностика системы охлаждения Cummins ISF3.8

Disconnect the radiator hose from the coolant outlet.

Install the hose to the coolant outlet, tighten the clamp and lower the free end of the hose into a measuring container.

Диагностика системы охлаждения Cummins ISF3.8

Start the engine and warm it up at the rated speed for one minute, while monitoring the opening of the thermostat.

If the thermostat opens during this test, repeat it. Permissible coolant temperature 38˚C

Stop the engine and measure the volume of coolant in a measuring container.

If the volume of collected liquid is greater than the allowable volume, the thermostat must be replaced.

Permitted volume 100 cm3

Removal and installation of the thermostat

Диагностика системы охлаждения Cummins ISF3.8

Disconnect the negative cable from the storage battery.

Drain the coolant.

Unscrew the mounting bolt, remove the cooling system bypass pipe and O-ring.

Диагностика системы охлаждения Cummins ISF3.8

Disconnect the upper radiator hose from the coolant outlet.

Remove the bolts securing the coolant outlet pipe.

Remove the outlet pipe of the cooling system.

Диагностика системы охлаждения Cummins ISF3.8

Remove the thermostat

Install the thermostat

Диагностика системы охлаждения Cummins ISF3.8

Install the coolant outlet and tighten the retaining bolts. Tightening torque 7 Nm

Connect the upper radiator hose to the coolant outlet.

Install the cooling system bypass pipe.

a) Install a new O-ring.

b) Install the bypass pipe of the cooling system and tighten the mounting bolt. Tightening torque 24 Nm

Fill with coolant.

Connect a wire to the negative plug of the storage battery.

Start the engine and check for leaks.

Examination

Note: as a rule, numbers are printed on the thermostat housing, indicating the temperature of the beginning of the valve opening.

Clean the contact surfaces using an abrasive sponge.

Диагностика системы охлаждения Cummins ISF3.8

Check the thermostat seal for damage. If damaged, the thermostat must be replaced.

Диагностика системы охлаждения Cummins ISF3.8

Диагностика системы охлаждения Cummins ISF3.8

Check the opening temperature of the thermostat.

a) Dip the thermostat and thermometer in a container of water and heat slowly.

Note: The thermostat and thermometer must not touch the side of the container.

b) Check the opening temperature of the thermostat valve.

Opening start temperature 79 - 8C

Full opening temperature 94˚ С

Диагностика системы охлаждения Cummins ISF3.8

Check the cooling system bypass

a) Clean the nipple with soapy water.

b) Dry with compressed air.

c) Clean the O-ring grooves.

Диагностика системы охлаждения Cummins ISF3.8

d) Check the O-ring groove for damage. If damaged, the bypass must be replaced.

Removal and installation of the coolant heater

Disconnect the negative cable from the storage battery.

Drain the coolant.

Disconnect the wiring from the coolant heater.

Disconnect the coolant heater. Tightening torque 55 Nm

Диагностика системы охлаждения Cummins ISF3.8

Apply a coat of sealant to the threads of the heater.

Sealant 3375066 or equivalent

Installation of the coolant heater is carried out in the reverse order of removal.

Examination

Clean the hole for the coolant heater installation.

Диагностика системы охлаждения Cummins ISF3.8

Check for damage to the threads.

Clean the heater with a cloth.

Make sure there are no deposits or cracks on the heating element and O-ring.

Диагностика системы охлаждения Cummins ISF3.8

Check the resistances of the coolant heater. It should be within acceptable limits. Coolant heater resistance:

- the minimum value is 18.2 ohms;

- the maximum value is 21.1 ohms.

Диагностика системы охлаждения Cummins ISF3.8

Removal and installation of the cooling fan

Disconnect the negative cable from the storage battery.

Remove the ancillary drive belt (article - Replacing the drive belt for Cummins ancillary units ISF3.8)

Remove the fan shroud.

Unscrew the 4 bolts securing the fan, remove the fan and spacer.

Attention, do not hold the fan by its blades. Torque:

- M6 - 10 Nm;

- M10 - 43 Nm;

- M12 - 77 Nm.

Remove the fan pulley.

Диагностика системы охлаждения Cummins ISF3.8

Диагностика системы охлаждения Cummins ISF3.8

Remove the four bolts securing the fan hub and remove the fan hub. Tightening torque 33 Nm

The cooling fan is installed in the reverse order of removal.

Examination

Clean the pulley, spacer and fan hub with solvent and dry with compressed air.

Диагностика системы охлаждения Cummins ISF3.8

Диагностика системы охлаждения Cummins ISF3.8

Check the fan pulley for damage or cracks.

Check for damage to the fan hub, hub chamfer, and check the fan hub for signs of gland leaks.

Диагностика системы охлаждения Cummins ISF3.8

Диагностика системы охлаждения Cummins ISF3.8

Rotate the fan hub and check for light and quiet rotation.

Check the fan hub bearing.

a) Check the bearing for wear.

b) Check the radial and axial play of the bearing. Replace the fan hub if the axial play exceeds the maximum value.

Maximum axial play of fan hub 0.15 mm

Диагностика системы охлаждения Cummins ISF3.8

Check for damage, loose bolts, bent or loose blades on the cooling fan.

Replace fan if necessary. When replacing a fan, use a part with the same part number.

Диагностика системы охлаждения Cummins ISF3.8

Caution: Do not straighten the bent fan blade, but replace the cooling fan.

Check the fan shroud for damage. Check the gap between the fan cowl and the fan, it must be within the permissible range.

The limits of the allowable clearance are 5.08 - 10.16 cm

Диагностика системы охлаждения Cummins ISF3.8

Radiator

Cleaning

Blow out the radiator with compressed air to remove dirt from the core.

Air pressure 552 kPa

Note Keep the hose nozzle at least 15 cm from the radiator core. so as not to damage the radiator.

Диагностика системы охлаждения Cummins ISF3.8

Examination

Check all hoses for cracks, cuts and wrinkles. Replace hoses if necessary.

Check for damage or leaks to the radiator and radiator gasket.

Remove the radiator cap.

Caution: When the engine is hot, this operation must be carried out with care as water and steam are under pressure.

Check the radiator cap using a radiator tester.

Note: if there are traces of liquid and / or foreign deposits on the lid, rinse and blow the lid.

By moving the tester piston, evenly and slowly (1 stroke of the tester piston in 1 second), pressurize the steam valve of the radiator plug and make sure that the valve opens under air pressure.

The radiator cap must ensure tightness within 14 kPa of the value indicated on the cap.

Диагностика системы охлаждения Cummins ISF3.8

If the valve opening pressure is less than the minimum, replace the radiator cap.

Check the cooling system for leaks.

a) Fill the system with coolant and connect the tester with a hose to the radiator neck as shown in the figure.

Диагностика системы охлаждения Cummins ISF3.8

b) Warm up the engine.

c) Using a tester, pressurize the system to 138 kPa and check that the pressure does not drop.

If pressure drops, check the radiator hoses and pump for leaks.

Install the radiator cap.