- Caterpillar Products
- All Cat Engines
Introduction
When a cooling system with glycol develops a leak into the oil system, the leak source must be found and repaired. The amount of glycol contamination of the engine lube oil must be determined and the appropriate action taken. Depending on the severity of the coolant leak, the required action will differ.
Customers who use Scheduled Oil Sampling can usually determine leaks at an early stage and can clean the engine lube system with just an oil and filter change. In addition to the positive indication of glycol, the increase in sodium levels in the used oil analysis is another method to define a coolant leak. The supplemental coolant additives contain sodium compounds which will appear as increased sodium in the metal analysis.
Oil analysis can result in one of the four different "Coolant Leak Indications" that follow. There is a different "Clean-Up Procedure" for each one of the "Coolant Leak Indications". The "Coolant Leak Indications" and associated "Clean-Up Procedures" follow:
Coolant Leak Indicator 1
The oil analysis may indicate positive glycol, but the sodium levels do not show any increase. An oil analysis of a sample of the new oil that was used in the engine should be made. Some new oils have additives which will give positive glycol results.
Clean-Up Procedure 1
No coolant leak has occurred and no further action is required.
Coolant Leak Indicator 2
The oil analysis indicates positive glycol and the sodium level in the oil has also increased. Examine the oil filter for any signs of metal particles or heavy residue on the filter surface. If none exists, repair the source of the leak.
Clean-Up Procedure 2
Change the oil and filter. No other clean-up is required since the amount of coolant in the oil was limited. But, continue to check the oil filter for any residue or metal particles at 50-hour intervals during the next oil change period to be sure that the problem has been corrected.
Coolant Leak Indicator 3
The oil analysis indicates positive glycol and the sodium level in the oil has also increased. Some water in the oil may also be noted. The oil and the filter now indicate a heavy, tacky, black or gray residue, but no signs of metal particles are evident. Customers who do not do oil analysis will usually find the coolant leak in this manner. This is a situation where coolant has leaked into the engine oil.
Clean-Up Procedure 3
A. Find and repair the coolant leak.
B. Drain the oil and install new filters. Fill the engine crankcase with a mixture of 75% of the recommended engine oil and 25% butyl cellosolve (Ethylene Glycol Monobutyl Ether). Do not mix more than the 25% butyl cellosolve (Ethylene Glycol Monobutyl Ether) or use a lower viscosity oil. The resulting mixture viscosity will be too low to provide proper lubrication.
Note: Butyl cellosolve (Ethylene Glycol Monobutyl Ether) is a strong liquid solvent and extreme care should be used when handling it. Keep it off of your hands because it can cause skin injuries. Butyl cellosolve (Ethylene Glycol Monobutyl Ether) will damage any finished surfaces. In the event of spillage, flush the area with clean water immediately.
Butyl cellosolve (Ethylene Glycol Monobutyl Ether) can be obtained through sales offices of the Dow Chemical Corporation.
C. Remove the radiator cap to keep the coolant system pressure at a minimum. Start and operate the engine until the jacket water temperature causes the coolant thermostats to open. (It may be necessary to block air flow through the radiator.) Run the engine at 75% of High Idle and NO LOAD to maintain the jacket water temperature and keep the thermostats open. Continue to operate the engine at this condition for approximately 20 minutes. This will allow the butyl cellosolve (Ethylene Glycol Monobutyl Ether) to dissolve the sludge in the lubrication system.
D. Stop the engine and drain the oil and solvent mixture from the engine. An assessment can now be made as to the effectiveness of this cleaning process.
E. Inspect the oil filters for any sign of metal particles which are an indication of engine damage. If any particles are found, the engine must be disassembled to determine the areas of damage and the steps necessary to clean and repair the engine.
F. If the oil filters do not show any metal particles, remove the oil pan and check the cylinder block inner walls and the oil pan for any sludge. If the block and pan are clean, install new filters and fill the engine with new oil. The filters should be checked at 50-hour intervals during the next oil change period for any signs of sludge and metal particles. If the filters are clean at the end of this period, the normal oil and filter change periods can be used for future maintenance.
G. If the oil pan and cylinder block are "dirty" after this cleaning process, disassemble the engine, clean, inspect, and replace parts as necessary. The crankshaft and rod bearings should be checked as part of this inspection process.
Coolant Leak Indicator 4
The oil analysis indicates positive glycol and the sodium level in the oil has also increased. Water in the oil may also be present. The lubricating oil and the filters show a heavy, tacky, black or gray residue and metal particles are present on the filter and in the pan.
Clean-Up Procedure 4
The engine must be disassembled, the source of the coolant leak repaired, the engine cleaned, and new parts installed as necessary. DO NOT use the butyl cellosolve (Ethylene Glycol Monobutyl Ether) and run the engine to clean it as this can cause more damage to the engine.