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Discussion Starter #1
Gearing up for my annual maintenance on my Westerbeke 30Bthree.

One task I have not yet tackled is replacing/flushing the coolant - I have had the boat coming up to 4 years, and have not done this before. I have also noticed some rust in the expansion tank, which makes me think a good flushout would be a good idea. Any best practices?

I was thinking disconnecting the hoses to the heat exchanger would be a good place to start - I can find no obvious drain plug...
 

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Does your Westerbeke service manual actually suggest changing the coolant and at what interval? Also what type of coolant is recommended? Many new diesels require Extended/Long Life coolant such as Dexcool, very important. Changing your coolant might not be necessary.
 

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Even dexcool has a life of 5 years, so 4 years is close to due.

The best coolant to use is not dexcool, but one of the newer universal extended lifetime ones, like prestone extended. They are a hybrid of organic acid (dexcool) and older technology.

Use distilled water to dilute, or buy 50/50 coolant.
 

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I did a bit more research, and Prestone Extended is a organic-acid technology coolant (OAT). I would be more happy using a hybrid (HOAT) coolant, and the easiest one to find on the high street is Valvoline Xerex G-05.
 

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Discussion Starter #5
FYI, in researching this I came across this article from MaineSail. It outlines some of the steps required - seems a bit of a pain to remove the heat exchanger to replace the collant, but unless somebody has any easier suggestions I guess that'll be the path I follow:

If changing antifreeze, the best thing to do, especially if your engine had or has "Death-Cool" in it, is to thoroughly flush it out, clean it, and start fresh.

To do this on a Westerbeke;

1- Remove t-stat and replace cover housing using a spare gasket

2- Remove HX (might as well clean and have pressure tested)

3- Purge old AF out of engine with pump into 5 gal bucket.

4- Use an acid resistant pump and circulate Rydlyme through engine block to clean cooling passages

4- Flush Rydlyme with water then fill bucket with distilled water and circulate through engine

5- Drain off what you can of the distilled, replace HX, t-stat and add antifreeze. The "Globals" are good. Death-Cool (AKA Dex-Cool) does NOT like all the dissimilar metals in marine engines and can create Dex-Sludge.

Death-Cool Sludge:
http://www.pbase.com/mainecruising/image/108349271.jpg


6- Purge air and test AF concentration with AF tester..

Circulating Rydlyme:
http://www.pbase.com/mainecruising/image/122459307.jpg

Connection points:
http://www.pbase.com/mainecruising/image/122459310.jpg


For air purging I replace the cheap "pet ****" on top of the t-stat housing with a 1/4 turn ball valve. I then add a barb and some clear hose to it. Run the hose well higher than the highest point in the cooling system. Fill the hose with AF using a transmission funnel, open valve and start engine. As the t-stat opens and closes AF will gravity feed into engine and no air will be left in the system. Air=bad. Once the system is no longer taking AF out of the clear tube close the valve and drain the hose back into the AF container..

Air Purging Valve:
http://www.pbase.com/mainecruising/image/112297123.jpg
 

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Wow. Lots of work. Like I said confirm that it actually needs replacement. Fleetguard makes test strips that I purchased on Amazon, or I'm sure you could send it out for testing. I have my oil analyzed for under $20. Also I believe the Longlife coolants can be refreshed with a bottle of additive. Some of the auto dealers(Ford? Chrysler?)sell it for the diesel guys. I think the key with the Dexcool or the like is that it hasn't been contaminated with regular coolant. The test strips will show that. 'IF' your engine has Dexcool.
 
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