Changing the coolant

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william vanwagoner
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Joined: Wed Nov 02, 2005 8:59 pm
Location: Destiny #229 Long Beach CA

Changing the coolant

Post by william vanwagoner »

Has anyone changed (flushed) the coolant in the C350? If so, any hints. I am getting ready to do this for the first time, and any help would be appreciated. On my previous boat, a Catalina 30, changing the coolant was quite a chore due to the need to evacuate the air out of the system while keeping the engine from overheating. Has anyone experienced similar problems during coolant changes on the 350, and if so, how did you deal with them?

Thanks,
Bill, #229
KenKrawford
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Post by KenKrawford »

Bill,
I haven't changed the coolant on my 350 but did have problems with air in the cooling system of my C34. I finally solved the problem by motoring (not idling in neutral) with the radiator cap off. Don't ask me why, but that finally solved the air/overheating problem.
Ken Krawford
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C350 # 351
Lake Lanier, GA
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TBOT422
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Joined: Sun Jun 26, 2011 5:36 pm
Location: Clearwater, FL

Re: Changing the coolant

Post by TBOT422 »

Any suggestions on getting air out of the coolant system?

I recently had to replace a leaking hose and the zinc in the heat exchanger and replaced the coolant in the process. Since that time, the coolant recovery tank level does not seem to vary significantly from cold to hot. The engine does not overheat, but the recovery tank level does not change as much as it used to. The level seems to only change about 1/4" or less from cold to hot, and I think it used to be much more. I am assuming I still have air in the system somewhere allowing the coolant to expand into the air cavity rather than the reserve tank. I've opened the petcock at the thermostat while the engine was running and also opened the petcock drain on the heat exchanger (engine not running) as per the manual, but they did not seem to have much affect. When the engine is cold, I open the raditor cap and the manifold is full to the brim (above the surface where the cap seats).

I read that there is another petcock on the hot water tank (not even real sure where that is).

I still have the clear tube going from the recovery tank to the manifold, and it has about a 4" to 6" section which is air rather than coolant. Running the enine at idle until it reaches operating temperature of 170 degrees does not create enough coolant expansion to move this bubble all the way to the recovery tank.

Am I correct that once the engine reaches operating temperature of 170 degrees, there won't be any more expansion of the coolant?

Since the engine is not overheating, there is clearly enough coolant in the system to function, but I don't think the recovery tank is functioning properly.

Any suggestions?

Thanks
Gary
The Best of Times (#422)
Gary & Janet
The Best of Times (Hull #422)
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