Best way to refill anti freeze loop

[Rick]

Looking for a better mouse trap on replacing my antifreeze. I recently got around to removing the heat exchanger core for service. I used my oil boy to remove the antifreeze from the loop which runs to my water heater which is under the front v berth (good 20' to the heater and back).

Now, how to put new stuff in? Filliing the holding (heat exchanger) tank and burping the system seems like it is gonna be tough because of a cold engine and closed thermostat and fact that the refill is hard to get too because of companionway and its on top of engine.

Anyone have any ideas? One I did have would be to again disconnect one of the lines running to the water heater run and use a drill pump with a hose place in anti freeze jug. That could help bleed the long loop.

Then?

Cheers

Boat is a 95 Hunter 336 with 3GM30F

 

[navigator97]

What I have done in the past, and will do again in the coming weeks, is to drain the heat exchanger thru the pet cocks and vinyl hoses attached. Then I disconnect the hoses from the engine to the water at the engine end (both) keeping them "up" until I can put a pail under one and lower that one. I then use the dinghy air pump and pump air into the other hose that is still "up" and let the air blow out the rest the coolant into the pail. The Yanmar 2gm20F and the heater hoses and heater coil hold about 1.3 Gallons.

 

[All U Get]

I just changed out the hot water tank and had to drain the lines of antifreeze. The PO had installed shutoff valves on the supply and return lines at the engine which made the draining a snap. The next step was having Maine Sail install a "T" with an additional valve that we would use to fill and burp the antifreeze. He added a short length of 1/2 inch tubing with a funnel that was held higher than the engine allowing it to fill the system. To keep the burping from splattering when we ran the engine, he held a towel over the funnel. We started the engine and as it warmed MS cracked the valve several times to release the expanding warm antifreeze into the tube. This was dumped into a bucket and repeated several times until we reached running temp. The valve was closed, the tubing and hose barb were removed, and a plug was tightened to the "T". :dance:
I remember my father running the car without a radiator cap until he could get it fixed, this was a spin on that same idea. I'll get a picture when we're back on the boat.
All U Get

 

[All U Get]

Hi Rick,
Here's the picture.
All U Get

 

[jibes138]

I just pulled and cleaned my heat exchange so had to refill my anti freeze. I kept overheating and once it starts to overheat it goes up fast so you need to shut it down immediately if you have the problem. I burped all the lines and pulled the thermostat to fill the section from the pump to the thermostat, etc. What finally worked was actually easy, I pulled the top hose off the hot water heater and replaced it with a short length of hose. Holding that hose above the height of the anti freeze tank I filled the hose until anti freeze came out the top of the tank, this made sure the whole loop was filled and seemed to get all the air out. You lose a bit when you put the hot water heater hose back on but it didn't seem to hurt. Temp is now rock steady at 160 degrees (universal M25) even with 80 degree raw water. You should also have a valve on top of the thermostat housing to blled any air out of that housing if it is like mine.

 

[Stu Jackson]

Dave's right.

Here's how to BURP a Universal

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

 

[Bob 04 H260]

I intend to change the coolant in my 3GM30E Yanmar this fall when we get back to the boat so I am following all these suggestions as this will be my first time doing it.

I noticed we have a "T" in the hot water tank loop with a cap on it. From what I am reading here it would be used to bleed air out of the system ? Would I just add a length of hose to this to allow air out or also use a funnel on the hose to add additional coolant as well ? Could my oil extraction pump be attached to this "T" and used to draw coolant through the hot water tank loop ?

Any tips appreciated !

thanks, Bob

 

[jibes138]

air extraction

Since the system is a pressurized closed system what you want is all the hoses, heat exchanger, water heat, and engine passages to be filled to start with. One problem with it filling is water doesn't really flow until the thermostat opens and then the thermostat is hit with cold coolant and closes right away, so in the meantime the engine overheats. The self priming ability of the water pump doesn't seem too good either. So I would use that T - fitting maybe with a funnel to fill it until full, but adding a length of hose to get it up high will help coolant flow into higher parts of the system. When you first fill your system air will rise to the highest point and get trapped, so you want as much out to start with as you can. Once your engine is running and not overheating and flowing coolant you want to run it at some high RPM to get a lot of flow for a little while to drive any more trapped air out.