SERVICES :: Service Tip #1

Coolant quality: corrosion

One of the biggest service issues that have come to plague us in the last 15 years is coolant quality. It used to be that when the radiator or header tank was low, we would just top it up with fresh water. In the mid 1990s we started seeing a marked increase in internal corrosion problems. This may be due to changes in metallurgy, but our suspicion is this is more the influence of the popularity of Reverse Osmosis Water Makers at around that time.

In any event, this has become a most serious and insidious problem. We have seen it manifest itself in many ways. The most common is radiators having to be re-cored or replaced. As painful as this is, it pales in comparison to other cases. We frequently see freeze plugs (commonly known as core plugs and water jackets) rusting out. Those are designed to be sacrificial and tend to corrode out before the block. The problem is once one starts leaking, all the others are close behind. This may mean stripping down a great deal of the engine and removing the cylinder head in some cases. We recently had a large 6 cylinder wet linered engine in our shop whose liners had literally rusted through and were leaking coolant into the oil pan. In a dry linered engine such as the 6.354, a rust hole in the liner means a new block or, effectively, scrapping the engine.

The shame of all of this is how terribly preventable this situation is. If we just put acceptable quality coolant in our engines and flush the cooling system annually, it has the potential of saving $1000’s of dollars. The customer with the big 6 cylinder paid nearly $25,000 to overhaul his engine.

What is acceptable quality coolant? Any “name brand” pre-mix coolant is acceptable for most diesel engines. Some manufacturers specify their own brand, and in such cases it is a good idea to use theirs. Most manufacturers use a MIL spec, ASTM, or SAE specification which most quality coolant manufacturers adhere to. Use a pre-mix, whether 50-50% or 33% (the latter being more than acceptable in the Caribbean). If unable or unwilling to use a pre-mix, make sure that any water that is added is distilled water only. The presence of any minerals will accelerate the corrosion practice. When you flush your cooling system, be sure to use a good quality radiator flush. We like Loctite 18E because it seems to clean all the rust and scale out of most cooling system with one application. After following the instructions, keep flushing the cooling system with fresh water (this does not need to be distilled) until it comes out clear and free of debris. Then fill it up with your pre-mix coolant and you’re good for another year.

In addition to providing corrosion protection, Ethylene Glycol coolants also protect against freezing (luckily not an issue in our Market) and boiling. A 50% mixture of Ethylene Glycol Coolant (EGC) protects the cooling system from boiling to 226 degrees F (109 degree C). A 40% mixture protects the cooling system up to 222 degrees F (106 degrees C). The pressure inside your cooling system raises the boiling point even further, but it is nice insurance to have the ECG mixture in case of a pressure leak in your cooling system.

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Tel: +1(284)494-2830/440-2830

Tel: +1(284)494-2830/440-2830

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