Coolant contamination is a very serious threat to any lube system. Small amounts of antifreeze can cause severe corrosion. It is especially harmful to engine main and rod bearings where contamination can lead to engine seizure. Antifreeze can enter a system from various sources. Virtually every one of the problem areas can be corrected with minimal maintenance action when compared to a complete overhaul. Sources that should be investigated when a contamination problem is detected are as follows:
- Leaky oil coolers
- Defective seals
- Blown head gaskets or cracked heads (Engine)
- Leaking seals or gaskets on wet side liners (Engine)
- Cracked block (Engine)
- Contamination of new oil by dirty containers
Detection of water / glycol leaks requires a combination of tests. The least sensitive test is the water crackle test. This test involves placing a drop of oil on a hot surface. The presence of water is indicated if the oil splatters or bubbles. This test will detect levels of water down to 0.1%. Its' drawback is that any detected water may be from condensation as well as coolant contamination. There is also a possibility that even with coolant in the oil there may be no detectable water due to evaporation at high engine temperatures. Therefore, this test should be used with caution. Water is most accurately measured through the use of a Karl Fisher water tester. (In small amounts)
The definitive test for identifying glycol is a chemical test. The test involves shaking the oil sample with a solution of chemicals and observing a color change. A positive reading in this test will be noted if there is in excess of 300 parts per million glycol present. This condition is reported to the user as positive ethylene glycol and should be taken seriously.
Spectro-chemical analysis is of value in detecting very small amounts of glycol. Potassium, sodium and boron are trace metals found in most coolant formulations. Their presence in engine oil can precede detection of the glycol itself. This data usually gives maintenance personnel sufficient warning that a problem is forthcoming. One caution is advised in using these levels for monitoring glycol contamination. Some oils use sodium and or boron as part of their additive package. When this is the case, the new oil sodium and boron levels must be considered as a base line and amounts over these as contributions from glycol contamination.