Drain and Flush
Drain and Flush Cooling System
Q: I recently purchased a 1971 MGB. Iím looking to drain and flush the coolant system and I notice that the radiator has no drain plug. I assume this is the way they came? Can you fully drain the radiator by pulling off the lower radiator hose? Is there a better way to drain it, without removing the radiator? Do you know if anyone has designed a modification to the lower tank to accommodate a screw-in type drain plug?
Thanks for your help.
West End, North Carolina
A: Yep, this is the way they came. And other than the oversized aftermarket units, OEM style replacements would be the same. Thereís room underneath to put a drain in, and they used to sell a universal kit for that, but I have not seen it lately. Most cars these days are already equipped with one and/or have plastic cores that would not accommodate installing one. If this is something you feel you really need, Iíd mark the best spot and remove it to do so. Maybe even bring it to a shop that specializes in radiators. I have my car almost 25 years and never found not having one much of a hindrance.
On the '71, like my '73, the lower hose connection is bent up at the end a bit where it connects to the lower hose from the engine. In flushing the system, I drain it by removing the hose and usually just keep putting fresh water in until itís clear coming out. Otherwise, as you note, removing it entirely is the best way.
I hope that helps you. Let me know what you do and take pictures if itís something new.