Air to Boil Procedure for EDI Ford Industrial Engines

Transcription

1 Air to Boil Procedure for EDI Ford Industrial Engines Table of Contents Page Air to Boil Procedure 2 Special Equipment 3 Test Procedure 3 Boiling Point of Coolant 4 Recommended Check Points 5 Test Results 6 Engine Compartment 7 Recirculation Test 7 Summary 8 Conclusion 8 Rev 0 1

2 AIR TO BOIL PROCEDURE Air-to-boil (ATB) is the ambient temperature at which the coolant will boil, causing the cooling system to fail. An ATB test will show if the system is adequate for cooling the engine in high ambient temperatures. For this test to be accurate, it should be run at ambients of no less than 80 F. Several temperatures are taken during ATB tests which are critical to the operation of the cooling system. The: temperature difference across the engine temperature of the coolant leaving the engine temperature of the air in the carburetor temperature in the engine compartment oil sump temperatures are all indicators of the performance of the system. The machine should be run at the highest duty cycle possible. For constant load applications, such as pumps and generator this is simple to do. For variable load applications such as loaders or vehicles an experienced driver should be used as a less skilled operator will not be able to load the engine as heavily. The application should be tested throughout its speed range and at idle as the reduced air and coolant flows at the lower speeds may actually create a more difficult cooling situation. Engine Distributors Inc. recommends the following steps in developing a cooling system for its engines: 1. Design an initial system using the previously stated guidelines in this manual. 2. Test system as described in the following procedures as stated in this section. 3. Modify system, if required, to correct discrepancies found in tests, based on our accepting guidelines. If these steps are followed, the cooling system should be able to cool the engine properly and continue to do so for the expected lifetime of the application. After selecting a cooling system, it must be tested extensively. The application should be tested in conditions to represent the worst case cooling situation the engine could ever see. The test must be performed in a manner that ensures repeatability. If possible, identical tests should be run on multiple applications to increase accuracy of results. The different operating conditions include: Wide Open Throttle (WOT) and Maximum Load: at the maximum level of heat generation by engine. If application can not be run at this level, test should be performed at highest possible load. Idle Test: due to low engine speed air and coolant flow may be insufficient to provide proper heat dissipation. Rev 0 2

3 Special equipment A standard, coolant thermostat for the engine being tested that has been soldered in the fully open position. Thermocouples K type F Test procedure To ensure that all tests conform to the same procedure, remove the thermostat and replace with one that is soldered in the open position. Always use fresh water or a water-ethylene-glycol solution for the duration of the test, as this gives a cooling fluid of known density. A 50% ethylene glycol 50% water cooling fluid mixture is recommended. This will: prevent freezing to about -40 F. aid in lubricating the water pump bearings help prevent corrosion of the coolant passages in the engine and radiator. A mixture above or below the recommended level will result in the following: Above 50% glycol the heat dissipation from the radiator will decrease Below 50% glycol coolant freezing may occur in some locations. For comparison with standards: Use production pressure cap Boiling point of coolant must be determined from Chart No. One on the following page. It is unreasonable to assume that coolant will always be maintained to the original percent of ethylene glycol. If the production ratio of ethylene glycol to water is not maintained in the field the boiling point of the system will decrease and the system may boil. It is advisable to test the system using lower pressures and less ethylene glycol for a more robust system. Set up thermocouples as indicated in Chart No. 2. Run engine until temperatures stabilize. Check for leaks in the cooling system. Run the machine at maximum operating load and record the temperature every 15 minutes, at the various positions indicated until the oil temperature has stabilized, (three readings giving the same results). From the data obtained, calculate the effectiveness of the cooling system to deal with high ambient. Sometimes, when a true load cannot be applied to the engine, other options can be used to simulate the actual load. These can be as follows: Utilizing the hydraulic to place the engine under load, ie., loading the engine via the hydraulics. Running the vehicle up an incline to place the engine in a loaded condition. Rev 0 3

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6 Test Results ATB temperature is defined as: Compute Temperature Difference across the engine by subtracting the bottom tank from the top tank. Calculate ATB and temperature difference for each set of temperatures recorded The following temperatures are the recommended limits for acceptance: Engine Temperature Difference (Delta T) In the range of 8 to 15 F If high indicates restriction in cooling system Carburetor Air Inlet No more than 10 F above ambient If high indicates need to relocate air inlet Oil Sump Between 212 and 250 F Spikes up to 284 F are acceptable at high ambients If high indicates need for increased air flow around oil pan or addition of oil cooler Engine Compartment Less than 50 degrees above ambient If high indicates insufficient flow through compartment 175 F max. temperature. Rev 0 6

7 Properly Ventilated Engine Compartment 1. The engine compartment is heated from two sources Air from the radiator if using suction fan Engine radiates heat directly in all cases 2. Engine compartment must be ventilated allowing air to flow over the engine and out of the compartment 3. High temperatures can cause premature failure of several engine components and possible fuel handling problems. 4. Radiator obstructions should be minimized Grill should have at least as much open area as the frontal area of the radiator Serial accessory radiators will impair air flow 5. Air must exit engine compartment without restrictions Free path should exist for air flow Radiator Recirculation Test Radiator recirculation occurs when air in the engine compartment is pulled around and into the radiator. Temperature variations of more than 10 F between neighboring points or above ambient at any point indicate recirculation exists If recirculation exists and engine passes ATB tests no need to correct but addition of radiator baffles would add to robustness of system. On completion of the tests, the results are processed to show: 1. The operating temperature limitations for the particular machine. 2. The efficiency of the airflow system. 3. If any problems of hot air recirculation exist. 4. Whether ventilation of the engine compartment is sufficient. Air-to-boil temperature is the most important test result. In general, an ATB temperature of 135ºF (57ºC) will be satisfactory for most applications. Higher ATB temperatures, 140ºF (60ºC), may be required for: Hot climates (this may include summer operation of agricultural equipment even in northern states) "Dirty" applications where some radiator plugging is unavoidable. Light duty applications may be satisfactory with ATB temperatures as low as 120ºF (49ºC). Engine compartment temperatures which are considerably higher than ambient indicate that there is too much restriction of airflow into or out of the engine compartment (or both). High engine compartment temperatures also are likely to cause "hot fuel handling" problems. Wide variations in the temperature of air entering the radiator at different positions or a differential of more than 10ºF (6ºC) between entering air temperature and ambient air temperature indicate recirculation around the radiator and a need for improved baffling. Rev 0 7

8 SUMMARY The air-to-boil test is the most comprehensive test useable for determining if the cooling system is sufficient. If a high ATB is not maintained coolant system failure is inevitable as the system ages and degrades. For the test to be accurate the following must be done: Take accurate data Determine accurate boiling point of coolant in system (factor of pressure and percent ethylene glycol) Ambient must be above 80 F To determine if the system is adequate the ATB test must be run with the system running at all speeds that will be seen in operation including maximum speed and load and idle. CONCLUSION An adequate cooling system in any application is essential. Without it the engine will fail. For a product to be successful, it must be able to perform well under the worst possible conditions, even after system degradation. The key in developing such a system is repeated testing until the system is proven. The guidelines presented here for design are only guidelines. It is impossible to produce a 100% guaranteed system on paper. Any cooling system must be thoroughly tested. Rev 0 8