We have a 2007 34' Mainship Pilot with a Yanmar 370. The coolant was changed when we bought the boat about 2 1/2 years and 200 hrs ago. I'm not sure when the AC was last flushed. Should I change the coolant this year when it gets winterized or is it good for another season or 2 or x number of hours? AC works great but had a lot of use this summer. I currently do not have access to all of my manuals. Would like to hear from people with your actual experience and recommendations. Thanks for your time!!
When to Change Coolant & Flush AC
- Thread starter sammy999
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OldDan1943
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Do you mean coolant for the main engine(s) and generator?
When it comes to the AC, keep the strainer clean.
When it comes to the AC, keep the strainer clean.
I just recently drained, flushed & refilled my Yan 6LYA in our 2008 34HT w/ 750 hrs. I'm sure the PO never changed it and we have not. I was pleasantly surprised when draining & flushing that coolant was very clean & clear. Largest concentration of sediment was in the o' flow container. I used Rotella ELC after doing some research.
If in doubt you can submit a sample to JG Lubrication services for testing. I have used them for oil sampling and coolant in our motohome.
With age of our boat I felt replacement was the prudent approach. My conclusion is that Yanmar recommendations are VERY conservative for avg recreational boater.
If in doubt you can submit a sample to JG Lubrication services for testing. I have used them for oil sampling and coolant in our motohome.
With age of our boat I felt replacement was the prudent approach. My conclusion is that Yanmar recommendations are VERY conservative for avg recreational boater.
catalinajack
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I don't know if it is relavant but how many vehicle owners EVER change their anti-freeze? Very few I suspect but yet vehicles seem to get along just fine. Water pumps do like fresher anti-freeze for the lubricant in the fluid but, even then, neglected water pumps last well over 100,000 miles, generally. Boat fresh-water cooling systems are closed so I don't see any difference. Still, I change anti-freeze every four or five years. Simple, inexpensive maintenance.
If talking about a diesel its not a good comparison to gassers. Talk to a diesel shop of builder like Freightliner and Google problems with "liners" on diesels. Many diesels have wet liners (coolant surrounds most of the liner) and w/o the correct corrosion inhibitors liners can be perforated by cavitation. Repair may be possible but a very major rebuild on a boat. Using the right AF for your engine / cooling systems can be very confusing and best to consult builders for recommendations.
I've just been through this with Yanmar on boat and Cummins in motorhome and info is far from straightforward. I even found different recommendations from Cummins & Freightliner but details not important here.
FF
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Weather the antifreeze needs to be refreshed depends mostly on the engine build.
An old style engine with cylinders that are bored in the block, or cylinders that are pressed into the block only need changes to drain junk and refresh their anti rust and water pump lube.
Newer engines that expose cylinder barrels to the coolant must have antifreeze refreshed on a regular basis.
The cylinder walls vibrate (think diesel knock) and the water in contact will create bubbles that can eat at the cylinder walls , over time a hole can be created.
Antifreeze for these engines contain SCA which is a slime that moves the bubbles off the cylinder wall.
These AF require monitoring with cards to have the amount of SCA correct.
To little , little protection, too much and the cylinder can be insulated from the coolant , so overheating is possible.
When changing AF a good 2 part cleaning solution and flush, flush, flush is part of the drill.
Change the AF filter at the same time, if one is installed..
An old style engine with cylinders that are bored in the block, or cylinders that are pressed into the block only need changes to drain junk and refresh their anti rust and water pump lube.
Newer engines that expose cylinder barrels to the coolant must have antifreeze refreshed on a regular basis.
The cylinder walls vibrate (think diesel knock) and the water in contact will create bubbles that can eat at the cylinder walls , over time a hole can be created.
Antifreeze for these engines contain SCA which is a slime that moves the bubbles off the cylinder wall.
These AF require monitoring with cards to have the amount of SCA correct.
To little , little protection, too much and the cylinder can be insulated from the coolant , so overheating is possible.
When changing AF a good 2 part cleaning solution and flush, flush, flush is part of the drill.
Change the AF filter at the same time, if one is installed..
Last edited:
firehoser75
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No you do not flush the coolant side of your engine's cooling system with Barnacle Buster. I would suggest that in most cases (where your coolant comes out looking clear and clean) that just flushing with fresh (distilled if you are fussy) water will do a decent job. When mixing the new antifreeze with water (50/50) use distilled water only. Some engines are very coolant tolerant (meaning they can use most coolants while others require very specific coolants). If your coolant side does need flushing (the coolant looks bad or much sediment) use a radiator flush like Prestone products or better yet one recommended by your engine manufacturer. Follow the product's directions.
I would suggest that for most pleasure boaters, taking apart the entire raw water side for a full off engine service including cleaning and pressure testing, and at the same time changing the coolant every 5 years is a good preventative service schedule. The service schedule can vary by engine and equipment (aftercoolers may need service more often) and manufacturer's recommendations should not be ignored.
I would suggest that for most pleasure boaters, taking apart the entire raw water side for a full off engine service including cleaning and pressure testing, and at the same time changing the coolant every 5 years is a good preventative service schedule. The service schedule can vary by engine and equipment (aftercoolers may need service more often) and manufacturer's recommendations should not be ignored.
ranger58sb
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The Yanmar manual should tell you when to change coolant, and whether to flush during the change. Instructions for our previous Cummins engines were specific, and of course they recommended Fleetguard anti-freeze and a Fleetguard anti-freeze flushing product. Yanmar may be similar...
ACs often need two kinds of attention. First is to just clean the strainers; I keep spare strainer baskets aboard in order to get the units back in service as quickly as possible on really hot days. You can probably develop a feel for how often they need attention, in your area. Second is periodic flushing with a product like Rydlyme or barnacle Buster.. and you may or may not need that where you are, may or may not need to do that very often, etc.
-Chris
FF
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Any big truck shop that sells antifreeze with SCA will always have the test kits as well as a good 2 part cleaner.
Marinas usually just have car cleaner and AF.
Yes, distilled water is required for the best job tho a rinse or 3 with tap water works fine.
Be sure to open all drain cocks to get all the crud out.
Marinas usually just have car cleaner and AF.
Yes, distilled water is required for the best job tho a rinse or 3 with tap water works fine.
Be sure to open all drain cocks to get all the crud out.
