All coolants come with an Active Ingredient we generically call Supplemental Coolant Additives, or SCA.  The purpose of this ingredient is to make good quality water less corrosive to your cooling system.  It does not make poor quality water acceptable.  It also cuts down on what is known as “liner pitting” in wet linered engines.

 The products have been around for many years and greatly extend engine life in terms of cooling system corrosion.  But the active ingredient in these products dissipates over a period of time.  When that happens, they need to be replenished in your cooling system.  There are many SCA products available: Nalcool, DCA and Racor to name a few.  It is important to consult your Operator’s Manual or local dealer to find out which ones are acceptable in your engine.

The way to determine the level of SCA in your cooling system is to use a test strip designed for the purpose.  It will tell you the level of corrosion protection in your coolant.  When low, you add the appropriate amount of SCA.  This is very useful and, indeed, essential to getting the expected life from your engine.

A simpler way of doing this is to just drain and refill the coolant in your system annually.  If you use a good quality coolant, the SCA is already in there.  Of course, if your engine holds a great deal of coolant, it is more cost effective to replenish the SCA.

If you fail to keep the levels of SCA up, the consequences are corrosion and liner pitting.  Liner pitting is the natural result of the combustion process in wet linered engines.  It manifests itself as 2 vertical rows of pitting 180 degrees opposite from each other on the outside of the liner.  It occurs when vapor bubbles collapse due to the expansion of the liner.  SCA coats the liner and reduces or eliminates the pitting.

Is there the possibility of “too much of a good thing”?  Unfortunately, yes.  The SCA have to stay dissolved in the coolant and held in suspension.  If you get too much in the coolant, certain parts of the mixture will “drop out”.  They crystallize and float around in your cooling system.  They can lodge in water pump seals, causing them to leak, among other things.

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 my 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.  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 (an L6414) in our shop whose liners had literally rusted through and were leaking coolant into the oil pan.  In a dry linered engine, 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 L6414 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.

In the next Service Tip, we’ll discuss Supplemental Coolant Additives, what they are and how to use them.

On a recent trip down island, I was told by several customers that they haven’t changed oil in 2-3 years, because the engine does not run very much.  They quote a 500 hour oil change interval from the Operator’s Manual and point that they only put around 100 hours per year on the engine.  So why should they change the oil or perform any maintenance?  The simple answer is because it will save them money.

First of all, oil oxidizes.  Our Service Manager, Dan Durbin, says: “Oil molecules combine with oxygen molecules over time forming acids, varnish and sludge. This can cause bearings and internal metal parts to erode. The base oils alone cannot meet the current needs of today’s lighter, high output engines. A highly complex additive package is added to the oil to make it last longer and perform better. But the ability of the base oil and additive package deteriorates over time, becoming enemies of engine life. I had a jar of oil that came out of an engine oil pan that looked like thick molasses due to “extended” oil change intervals performed by the owner. I kept the jar to show people. As it sat on my desk it got thicker and thicker, until finally it was a thick goo that did not flow when I turned over the bottle.”

Condensation also builds up in an engine that doesn’t run, which results in water contamination in the oil.

Low running hours are a terrible thing for a diesel engine.  A diesel is happiest when it is running with 70% or more load on it.  Running the engine 24 hours/day, 7 days/week will result in the longest running hours from an engine.  Sitting around idle is one of the worst things that can happen to an engine.

That is why engine manufacturers always give a time period in the maintenance schedule, as well as running hours.  Typically oil changes are given as a certain number of hours or 12 months, whichever occurs first.

Another important maintenance item to not skip is flushing the cooling system.  Check our website,www.partsandpower.com for Service Tips on coolant quality.  This is one of the most insidious problems diesel engine owners face.  Poor coolant quality results in many diesel engine problems or failures in the Caribbean every year.  The only proper coolant is distilled water, or glycol mixed with distilled water.  Even then, the coolant should be flushed annually.

Why do we need glycol (anti freeze) in the Caribbean?  It never freezes.  The reason is to keep your coolant from reaching its boiling point and evaporating.  Water boils at 212F (100C).  New generation engines routinely run as high as 226F (107.7C).  They don’t alarm until 235F (112.7C) or 244F (117.7C).  Plain water would evaporate at those temperatures.  A 50/50 mixture of glycol and (distilled) water raises the boiling temp of your coolant to 225F (107C).  The same mixture with a 7 PSI (0.5kg.cm2) pressure cap is raised to 239F (115C).  So a glycol mixture and proper coolant system pressure is critical.  Remember never to exceed 50% glycol in your cooling system.

Other maintenance items that are recommended may not be as important to the overall life of the engine, but will result in better fuel consumption, lower soot and noxious exhaust fumes, and quieter running.  These include checking, calibrating and repairing (as necessary) the injectors.  Also included is adjusting the valves.  The injection pump itself has recommended service interval as well.  If your engine has a timing belt, changing that is critical.  Consult your operator’s manual for the items required by your engine manufacturer.

Doing these maintenance items can greatly extend the life of your diesel engine.  This not only saves you money, but also makes sure that diesel engine will be there when you need it.  The easiest way to extend the engine’s life is by running it.  If your diesel engine is in a boat, make sure that it is run once a week, ideally under load.  If the engine is in a standby generator, make sure the exercise timer is activated and set to run, under load, once/week.  Ideally run them for an hour.  This will heat up the oil, dry out the moisture and recoat all the metal surfaces with fresh oil.

Changing oil and coolant is very cheap compared to changing an engine.