Coolant Dam or not?

[Rawze]

The coolant dam device does not work so well for it. Once you break the line, you will have 2(TWO) open ends in the coolant system (the hose and the fitting it went to) and any vacuum you have pulled will be canceled by this. One will suck in air and the other will pour out coolant at a high rate anyways, especially while your unscrewing it. Holding your thumb over one of them helps but then you need to block the lines off with plugs while your doing so.

been there and done that. lol.

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It is far easier to just simply drain about 5 or so gallons into a bucket.

When you want to put the coolant back into it and you have it all back together, pull a medium-hard vacuum (using a vacuum pump or coolant service kit) on the coolant system to get the air pockets out, then let the vacuum suck the coolant back in. That is the proper way to prevent engine damage.