Engine Antifreeze

[stevec22206]

Is there a step by step procedure for draining and replacing the antifreeze on the closed system of the M18 diesel with a hot water heater on board? I've seen some reference to the potential for air pockets if not bled correctly.

Steve

 

[Stu Jackson]

Engine Overheating 101 - How to Burp Your Engine (Reply #6) http://c34.org/bbs/index.php/topic,4518.msg26462.html#msg26462

This is more for assuring that you've gotten rid of the air bubble in the spring when you restart, which seems to be part of your question.

If your heater is higher than your engine, should be easy to drain. But why would you remove the coolant? You don't want the walls of inside of the engine dry or it'll rust out.

 

[Ralph Johnstone]

I've seen some reference to the potential for air pockets if not bled correctly.

Steve

I like to keep an accounting of what comes out, I try to put back in.

I drain into a calibrated container (big clear plastic juice container with lines drawn on it) and then mix up the same volume of new antifreeze. If I'm just a few ounces short of jamming all the new stuff back in, I don't worry about it. I'll top it up after the next outing. If much more, I closely monitor it and make sure I top it up after running hot for an hour or so. Either way, all air pockets will disappear after running hot for an hour. If they don't, then your engine will have a history of always running hot. And a future of always running hot. But I digress .

Having a water temp gauge is also a big help if you have trouble with large air pockets on start up.

Also, our water heater is lower than the engine so removing that portion of the antifreeze would be a major pain. I find it much easier to just change the antifreeze every two years to ensure that most of the antifreeze is being replaced on a regular basis.

 

[stevec22206]

We've owned the boat for going four years and I haven't changed the coolant. Don't know if the previous owner addressed it either. Am going to test it tomorrow and was wondering if it should be changed and how to go about it. Noticed on the Universal Motors spec sheet that there is a bleed valve and block drain valve. Having checked the link provided by Stu I think I'll follow those directions if need be. Getting ready to lay the boat up for the winter and want to be certain it will be protected.

Steve

 

[harv]

Just a few hints- the block drain valve is located on the starboard side of the engine. The drain valve "may" be reversed- OPEN IS CLOSED, CLOSED IS OPEN. Don't ask me how come, only some Catalina employee long gone may know.
Attach a hose to the drain valve hose leading to a container.
Some people take out the thermostat to make the engine come up quickly to normal heat value quickly.
The theory is that most bubbles will come up to the highest point- so run the engine at idle with the coolant cover off. Run engine unitl it reaches normal temp and top off. Run at that normal temp and if the engine dosen't overheat, you are good.

Others find that the engine will start to overheat. Run up the RPM to 2000 or so for a few seconds, which will circulate the bubbles, and shut down until cool (thirty minutes). You may have to do this few times.

Note that the M-18 dosen't have an overflow bottle but it probably has hose attached near the cover. Stick it into a glass bottle.

 

[harv]

Opps.- On that run up of RPM operation, you may have to put on the coolant cover. Depends on how fast it starts to overheat.
One of our extended family boats is a 85 Cat 27.

 

[weinie]

I had trouble "priming" the system until, I disconnected the hot water heater hose and replaced it with a short piece of hose. I then filled the engine with AF and burped it. Then I removed the short hose, connected the "lower" end of the hot water heater, and using a funnel, filled the other hot water heater hose with AF. I then reconnected to the engine it and reburped the engine.

 

[stevec22206]

Thank you for all the information. I will save this for future reference. I laid the boat up today for the winter. I checked the antifreeze with a tester before winterizing the engine. The result, the antifreeze tested good and the color still looks like it just came out of the jug. So, I'll rest easier knowing it's protected for another winter. I may change it in the spring prior to splashing. Nice to have the experience of others to guide me through it.

A side note: not a pleasant day putting her up and under cover. 4 months til splash. Winter sucks!

Steve