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you would need to drain the coolant and cause a potential leak point

use this instead if your worried.

http://www.canadiantire.ca/en/pdp/polar-pad-engine-heater-125w-0300004p.html

Sorry about the delay treeguy.

Here is a picture of the end going into the engine. The red plastic is the positive terminal cover on the battery so this angle is looking downward standing on...