Engine Coolant

[Island Time 1,235]

Today, one of my jobs was to look at a water heater that was not operating. Turns out it had a few issues, and is being replaced. While removing it, I took off the engine coolant  hoses, used to heat the water heater when the  engine is running. Rather than the nice clean coolant, green, yellow, or red, out came a thickened, black crap. I then had a discussion with my customer about coolant changes and  engine flushing. Never been done in 8 years, and 1/2 way around the world.

So, it made me think that a little jolt might be a good idea for some members here. When was the last time you flushed your engine coolant circuit? Many manufacturers require you to do this for warranty, and its not just for fun! Most coolants loose their inhibitor properties after a period. Some need changing every 2 years. 

So have a look in your header tank - where the coolant goes, and not just at the level - look at the color, if the engines cold, take off the top, look inside - is their sediment or anything settled on the bottom? If so, the system should be flushed before the coolant is changed. Its pretty easy. 

Go to your auto parts store, buy some coolant flush, follow the instructions on the bottle. Its basically like  this. Tip it in the header tank. Open any valves to water heaters, water based cabin heaters, or anything else the coolant passes thru.  Run the engine for  a few hours. Remove the lowest drain plug or bottom hose if there isn't one. Then use a hose and fill from the top, keep it going until  clean water only comes out the bottom. Let the water drain, put the bung/hose back on. If the header tank is discolored plastic, take it off and clean it or replace it. Remove the hoses to the water heater and any heat exchangers, flush with the hose. When water runs clear, drain and refit.  Refill with properly mixed coolant, as per coolant manufacturers recommendations, or engine manual. 

Next time you notice any discoloration of your coolant, change it! Discolored coolant is gritty, wears components, it's full off impurities and does not cool or protect your engine and ancillaries as it should.

Another job that should be part of your maintenance plan!

Happy Boating!!

[wheels 543]

The cheap Coolants need replacing yearly and there are a lot of cheapies out there.
If you want a quality coolant without paying through the nose, the Penrite range is extremely good, with their top end coolants having a 5, 7 and 8yr cycle life. However, when using coolants that can span that far, I suggest you get a test done every couple when getting toward the far end of it's life.
Coolants are the wrong word to call these additives. They do cool to an extent and they also safe guard against freezing, but the most important role is anti corrosion. They are Corrosion Inhibitors. I have seen engines that have had holes through cast iron blocks due to running with no inhibitor. The Nissan TD42 engine and Cummins engines are common for holes through blocks.
Any engine that has a Cast block and Ally Head MUST have an inhibitor added. That's simply a case of dissimilar metals in close contact causing corrosion.