Add news
March 2010
April 2010
May 2010June 2010July 2010
August 2010
September 2010October 2010
November 2010
December 2010
January 2011
February 2011March 2011April 2011May 2011June 2011July 2011August 2011September 2011October 2011November 2011December 2011January 2012February 2012March 2012April 2012May 2012June 2012July 2012August 2012September 2012October 2012November 2012December 2012January 2013February 2013March 2013April 2013May 2013June 2013July 2013August 2013September 2013October 2013November 2013December 2013January 2014February 2014March 2014April 2014May 2014June 2014July 2014August 2014September 2014October 2014November 2014December 2014January 2015February 2015March 2015April 2015May 2015June 2015July 2015August 2015September 2015October 2015November 2015December 2015January 2016February 2016March 2016April 2016May 2016June 2016July 2016August 2016September 2016October 2016November 2016December 2016January 2017February 2017March 2017April 2017May 2017June 2017July 2017August 2017September 2017October 2017November 2017December 2017January 2018February 2018March 2018April 2018May 2018June 2018July 2018August 2018September 2018October 2018November 2018December 2018January 2019February 2019March 2019April 2019May 2019June 2019July 2019August 2019September 2019October 2019November 2019December 2019January 2020February 2020March 2020April 2020May 2020June 2020July 2020August 2020September 2020October 2020November 2020December 2020January 2021February 2021
News Every Day |

Monthly Maintenance: Diesel Engine Coolant

Coolant was once always green but now comes in many colors.
Coolant was once always green but now comes in many colors. (Steve D’Antonio/)

Antifreeze is a critical component in any liquid-cooled internal combustion engine that relies on a closed cooling system. It should be referred to as “coolant” because it does much more than prevent freezing.

In a closed cooling system, excess heat created by the engine is absorbed by the coolant and transferred, via a heat exchanger, to seawater and pumped overboard with the exhaust gases. From the 1930s through the 1990s, nearly all coolant used in applications like this was the familiar green ethylene glycol (referred to as IAT, or inorganic acid technology), which provided corrosion protection and circulator-pump lubrication, offered freeze prevention down to about minus 30 degrees Fahrenheit when mixed at a 50-50 ratio with water, and elevated the boiling point about 15 degrees Fahrenheit above that of ordinary water. Pressurized cooling systems, such as those on all modern diesel engines, also raise the boiling point; at 15 psi, the boiling point of ordinary water is 250 degrees Fahrenheit.

Today things are different, mostly in the realm of choice; there is a range of coolants from which to choose, ­including organic acid ­technology (OAT), hybrid ­organic acid technology (HOAT) and ­nitrided organic acid technology (NOAT), along with some proprietary coolants designed for specific engines. These formulations afford engines greater corrosion protection and longer coolant life. Then there’s color: In addition to green, there is blue, pink, orange and red, and while those colors might be indicative of a particular chemistry, it’s no guarantee.

Always follow the coolant instructions provided by your engine’s manufacturer, and never add coolant without knowing what’s there already. In an emergency, you are better off adding water (preferably distilled, but anything will do in a crisis) than the incorrect coolant. The primary mission of coolant is to prevent freezing, but if that’s not an issue, water will work just fine short-term.

Coolant ­surrounds the outside of a heat exchanger’s “tube bundle”; if overheated, a film can be ­deposited on them, which can inhibit heat transfer.
Coolant ­surrounds the outside of a heat exchanger’s “tube bundle”; if overheated, a film can be ­deposited on them, which can inhibit heat transfer. (Steve D'Antonio/)

When changing ­coolant, whether to a similar or different chemistry, plan on flushing the system to remove sediment and all traces of old coolant. Remember, conventional ethylene glycol is poisonous, so don’t leave uncovered containers out where they can be accessed by pets or children, and always clean up spills (it evaporates very slowly), and dispose of old coolant properly.

If you’ve decided to replace your coolant, you should once again do so in accordance with engine-manufacturer guidelines, and in the absence of those, about every 1,000 hours or three years. Unless the manufacturer specifies one of the above-mentioned more-modern varieties, most sail auxiliaries and gensets can use conventional IAT; however, it should be formulated for diesel-engine use.

Diesel engines, particularly those that rely on a “wet” cylinder—wherein the outside wall of each engine-cylinder liner is in direct contact with the coolant—can experience a phenomenon known as cavitation erosion, sometimes called ringing. At each power stroke, the cylinder bulges slightly and then rapidly contracts, creating a void or cavitation bubble that implodes violently, and in doing so, removes some metal from the liner. This all occurs on a microscopic basis and takes time for damage to occur, but after enough time passes, it can lead to cylinder-­liner leakage and failure. This is rare on sailboat auxiliaries, but why risk it? By using a high-quality diesel-rated coolant (these include anti-cavitation additives), and changing it regularly, you will all but eliminate this possibility. Supplemental anti-cavitation additives are also available, and these can be added on an annual or hours-based model.

Since engine blocks are usually cast iron, coolant must include corrosion inhibitors (as well as cavitation inhibitors).
Since engine blocks are usually cast iron, coolant must include corrosion inhibitors (as well as cavitation inhibitors). (Steve D'Antonio/)

If you are using a concentrate (that is, a coolant that requires the addition of water as opposed to one preformulated), be sure to mix with distilled water only. Do not use tap or bottled water. Water that contains minerals can leave scale deposits within the cooling system, thereby impeding heat transfer. Unless otherwise instructed by the manufacturer, the mix ratio should be 50-50 for the best balance of corrosion, freeze and boil protection, as well as heat transfer (pure distilled water can transfer more heat than coolant, which is why it’s undesirable to increase the coolant-to-water ratio beyond 50 percent). Anything under a 30 percent ratio of coolant can allow biological growth to form within the cooling system, especially on engines that are used infrequently. So stick with the 50-50 ratio for the best results.

RELATED: Sailboat Diesel Engine Analysis

Finally, if you’ve never checked the coolant concentration in your engine, you should do so, especially before winter layup. If the coolant concentration is too low, it will freeze, which could cause significant and possibly irreparable damage to the engine. While the “floating balls” test tool works for ethylene glycol, a refractometer is more accurate, and it’s applicable to all coolant types.

Steve D’Antonio offers services for boat owners and buyers through Steve D’Antonio Marine Consulting.





Read also

Briggs: As Mud Hens return, Napoli sees 'light at the end of the tunnel'

Who was Billie Holiday and how did she die?

BMW's iconic kidney grille has gone through 13 major redesigns - tour all 88 years of its evolution




News, articles, comments, with a minute-by-minute update, now on Today24.pro



Today24.pro — latest news 24/7. You can add your news instantly now — here
News Every Day

Tragic Details About 'Macho Man' Randy Savage