SYSTEM DESCRIPTION

A complete system description must be documented in the Detroit Diesel Vehicle Sign-Off form.

Attach cooling system component prints, installation drawings, photographs, and sketches of the overall system to the Vehicle Sign-Off.

This information will assist in determining system approval and also serve as a reference point if future difficulties are encountered.

8.15.2 INSTRUMENTATION

The following instrumentation and materials are required to conduct a complete evaluation of the cooling system:

□ Thermocouples and associated readout equipment

□ Pressure gages and associated hoses and fittings

□ Thermostat

□ Stop watch

□ Light (flashlight, trouble light)

□ Water supply hose

□ Diagnostic data reader or Detroit Diesel Diagnostic Link™ software

□ Engine loading method

□ Tape measure

□ Flowmeters and associated hardware (if necessary) NOTE:

All instrumentation must be calibrated and in good working condition. Size and range should maintain data accuracy.

8.15.2.1 Thermocouples and Associated Hardware

This section discusses the attributes needed for coolant, air and oil in relation to thermocouples and associated equipment.

Measure air, engine coolant out, and lube oil gallery temperatures until the coolant and engine lube oil temperatures are fully stabilized. Other temperature measurements such as engine coolant in, engine intake air, and exhaust temperatures may be measured to aid in troubleshooting cooling system deficiencies.

All thermocouples, wires, and readout equipment must be compatible. All junction points should have wire insulation completely removed, cleaned, and securely joined for good electrical continuity. Polarity must also be correct.

Use calibrated matched pairs to obtain accurate temperature differential values.

A digital readout is preferred and should have 12V (DC) and 110V (60Hz AC) capability. A remote multi-channel switch can be wired into the circuit if the readout box does not have sufficient positions for all the thermocouples.

Location of the thermocouples is critical. The thermocouples must protrude into a high flow path and not touch surrounding surfaces. Ambient air thermocouples must be shielded from direct sunlight and not sense any radiated or recirculated heat sources. Radiator thermocouples must also be shielded from sunlight. The sump thermocouple must be in the oil while the engine is running.

8.15.2.2 Pressure Gauges and Associated Hardware

To measure water pump inlet pressure, use a381 mm Hg to +206.8 kPa (15 in. Hg, +30 psi), compound gage or 72.6 cm (30 in.) or greater “U” type manometer.

Additional pressure measurements may be required for analysis of the system.

Use a vent at each gage to expel all entrained air and water and ensure no blockage in the circuit.

All hoses must be full of the substance being measured.

NOTE:

Locating gages at the same height as the measurement point eliminates the need to correct the readings.

Hose length should be as short as is practical.

8.15.2.3 Thermostat

Both blocked open and operating thermostats are required. A thermostat must be blocked open to the proper dimension for obtaining correct data. Full blocking thermostats must be opened so the coolant bypass circuit is completely shut off. Make a visual check. The oil cooler bypass thermostat must be blocked to the minimum travel distance at full open temperature. Inspect and replace thermostat seals if necessary.

Figure 8-35 Thermostat

8.15.2.4 Sight Glass and Transparent Tubing

Observation of coolant aeration, flow direction, and velocity greatly assists in analyzing test results and determining system acceptability.

Install a sight glass in the engine water out line between thermostat housing and radiator inlet.

NOTE:

To avoid personal injury such as scalding or eye injury, thick wall transparent tubing must be used. Safety straps must be used with the sight glass and flow meters.

NOTICE:

All connections must be secured carefully and be routed so they do not kink and will not be damaged during testing.

Replace deaeration and fill lines with transparent tubing. It is also helpful to replace coolant return lines on heater, air compressor, filter, coolant conditioner, and other components that use engine coolant.

Sight glass and transparent tubing is useful during fill, drain, capacity check, deaeration, flow and pressure vs. engine speed maps, and drawdown tests. These visual aids should be removed for safety reasons prior to air handling, cooling index, and any other tests where the system is pressurized and high coolant temperatures are expected.

8.15.2.5 Graduated Container

An 3 gal (11 L) bucket, graduated in 1 qt. (.95 L) increments is recommended for most cooling systems.

The container is needed to determine total cooling system capacity, measure coolant removed during drawdown test, and coolant expelled during air handling test, and measuring water supply flow rate for fill test.

8.15.2.6 Pressure Cap

The pressure relief cap/valve must be functional and develop rated pressure.

8.15.2.7 Stop Watch

A stop watch is used in conjunction with a graduated bucket to set flow rate for fill test and to record time to expel all entrained air after filling the system (deaeration time).

8.15.2.8 Light

A flashlight or trouble light held against the sight glass or transparent tubing is helpful in observing coolant aeration. A light is also useful to look for top tank coolant agitation.

8.15.2.9 Water Supply and Hose

A water supply and hose capable of flowing at minimum 3 gal/min. (11.35 L/min) should be available to conduct continuous and interrupted fill tests. A flow meter that can regulate rate and measure capacity is ideal.

Normally a stop watch, graduated bucket, and a valve on the hose are needed to regulate water flow to the required fill rate.

8.15.2.10 Engine Loading Method

The test facility should provide a method for fully loading the engine, in order to conduct cooling index tests. The loading method will vary with application and test site location.

8.15.2.11 Tape Measure

Size and distance measurements of radiator assembly, fan components, and other related hardware

8.15.2.12 Flowmeters and Associated Hardware

Engine coolant out (radiator in) is the preferred location for measuring radiator flow. Inside diameter of flowmeters must not cause excessive restriction. Use engine coolant in (radiator out), only as a last resort because of added inlet restriction to the water pump.

The flowmeter should offer low restriction to the coolant flow, regardless of the type used (turbine, differential pressure, etc.). Refer to the manufacturers instructions for correct installation,

operation, and limitations of the individual flowmeter.