Don’t go cool on Valentine’s!  Time to show your engine some love.

From Ivan DeSouza, Owner and Certified Mechanic, Xtreme Marine Antigua
From my experience, the one area that is often overlooked by boat owners is the discipline of doing a FULL check of your boat’s cooling system.
Coolants play a pivotal role in preserving the engine heat balance and protecting your engine components against corrosion.
Your coolant checks should take place before you even think of packing the beers in the cooler, or ordering Panini’s to go for your wake-boarding session :).  For some non-technical, or busy boat owners, the following steps may be a step too far.  In our TOP TIPS, we are simply communicating the protocols that should happen; even if you have us or your own mechanic undertake them.
Do the basics before you head out:

Check the coolant level, ALWAYS.

Look around the engine compartment for any leaks; coolant, oil etc.  If there are leaks, wipe them up so that you can see any new leaks as they appear.

As you know, 1,000 is the magic number when it comes to diesel engines. (unless your engine manufacturer tells you different – refer to your boat manual).  In this case, after 1,000 hours of operation, you should be removing the heat exchanger and overhauling it.  This means remove it from the engine, disassemble it and take out the core.  Clean inside thoroughly.  Use a mix of muriatic and water and really clean out the salt build up that comes from salt water and, of course, the salty air here in Antigua!
One area that is often overlooked, is to clean the fresh water side of the heat exchanger too.
NEVER mix coolant brands.  You should keep to the same brand to ensure that a chemical reaction does not take place.  Coolants are, in the main, considered to be compatible, however, mixing coolants of two different qualities results in a mixture of intermediate quality; mixing a great coolant with a less superior coolant will result in a coolant that does not deliver a good level of performance.
Without going deep into the science side, ​if you decide to mix brands, you could be causing a build-up of sludge.  Sludge is very difficult to clean and it can go all over your engine. ​(NOTE:  You need to have free flowing sea water going through the mixing elbow).
Coolant plays a critical role in sustaining engine heat balance by actually removing the heat.  Operating with low coolant can lead to problems because a coolant cannot protect surfaces that it does not make contact with.
We always advise a mix of 50:50 already mixed.  We want to ensure that you are not inadvertently raising the boiling point of coolant as it does help lubricate the inner engine parts, too.  Boiling means steam as opposed to keeping it in liquid form.  Steam is not good!
So how often should you show your coolant some love?  Again, coolant should be changed every 1,000 engine hours.
We’re not suggesting buying your boat roses for Valentine’s Day, but a little TLC goes a long way in boat maintenance.