1979/02/19 Caterpillar

All Engines Using Ethylene Glycol in Coolant System

When there is a cooling system leak into the oil system, it is important that the leak be found and repaired rapidly and that the lubricating system be cleaned before the engine is put back into operation.

Customers who use Scheduled Oil Sampling can find leaks very soon and many times can clean the engine with just an oil and filter change.

There are probably four coolant leak conditions which can be found in the field and the procedure to use to clean the engine lubrication system is different for each:

1. A positive glycol indication in oil analysis coming from oil additives in new oil. Do an oil analysis on a sample of new oil of the same type the customer uses in the engine. Some oils will test positive in an oil analysis since they contain an additive which gives a positive result to the test for ethylene glycol. The time for color change in oil test will be same for new and used oil.

2. The oil analysis shows a small amount of ethylene glycol in the engine lubricating oil, and there are no signs of metal particles or heavy residue on the filters.

Repair the source of the leak and change the lubricating oil and filters. Do not use butyl cellosolve and run the engine to clean it up. Check the filters at a 50 hour interval for any signs of ethylene glycol or metal particles.

3. A check of the lubricating oil and filters shows a heavy, tacky, black or gray residue but no sign of metal particles. This is the way most customers, who do not use oil analysis, find first signs of leakage.

- Find the source of the leak and repair it; or drain the coolant and fill the cooling system with water while a check for the leak is made.

- Install new filters and fill the engine crankcase with a mixture of 75% SAE 30 or SAE 40 oil and 25% butyl cellosolve.

- Put a cover on the radiator until the jacket water temperature is high enough to open the coolant regulators. With the radiator cap removed to keep coolant system pressure at a minimum, run the engine at 75% of the high idle speed no load, to bring the jacket water temperature above the temperature needed to open coolant regulators. Run the engine for 20 minutes at this temperature.

- Stop the engine and 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 area of damage and the necessary steps taken to clean and repair the engine.

- If there are no signs of damage, drain the oil, remove the oil pan and check the cylinder block inner walls and the oil pan. If they are clean, all of the crankshaft bearings should then be inspected for any damage. Inspect all of the bearings. If any damage is seen or more than 33% of the lead tin overlay on the bearings for the crankshaft is worn off of the lower bearing surface, or if the bearings have run more than 2000 hours, install new bearings.

- If the oil pan and cylinder block are dirty after the cleaning process, the best procedure would be to disassemble the engine, clean and repair as needed.

- If bearings are good and engine is found clean, fill the engine with lubricating oil and install new filters. Check the filters at a 50 hour interval for any signs of ethylene glycol or metal particles. If the filters are clean, the normal oil and filter change periods can be used for future maintenance. If signs of ethylene glycol are found, use 50 hour interval oil filter changes and inspection until sludge cleans up. If metal particles are found, the source of the metal must be found immediately.

4. A check of the lubricating oil and filters shows a heavy, tacky, black or gray residue and there are metal particles present on filter or in pan.

Do not use butyl cellosolve and run the engine to clean it up as this can do more damage to the engine. The engine will have to be disassembled, the source of the ethylene glycol leak repaired, the engine cleaned and new parts installed as necessary.