[Gearman]

You have gotten a lot of advice here, but I had better success using an electric heater that connects to the lower radiator hose close to the actual radiator itself over an actual block heater that fits into a freeze plug location. Being at the low point in the system the warm coolant will circulate naturally warming more of the coolant I think since as the warmer coolant rises the colder will flow down to the heater in a circulating motion. One important point, you do need to make sure that the t'stat in the vehicle is not a completely sealed type. Many t'stats today will have a small ball check in them to let air pass by during a fill but not all. In the past where the design did not include that vent, I drilled a 3/32 hole through the t'stat plate to allow a small amount of coolant to pass through. (do not make the hole any bigger than that or the system will not function right. This will not give you "instant" heat, but my experience is the vehicle will warm up much faster than with a block heater. And as recommended by another member I would put it on a time for about three - four hours before your normal commute time. Good luck

 

[Gearman]

I keep going back and thinking of a pumped coolant heater. If only that second bypass line was rubber, could add a check valve on the second bypass line, then run the heater in series with the first. This would pump heated coolant directly though the block with minimal heat loss to the radiator or anything else…

Keep in mind that as soon as you start up the vehicle with the engine side already a warmer the T'stat will open faster, and the colder coolant from the radiator will flow in perhaps giving you a warm then cold effect rather than a steady rising warm. This is also way I think the lower rad hose heater solution could be better as it is warming more of the coolant.