[oil pan 4]

I swapped out the 3500 for a 2400w heater.
And tested it.
I powered up my 220v coolant heater and it works perfectly.
It sizzles as its working and heats the coolant 12'F as is circulates.

One of the tests I did was leaving a single 600w block heater on and then using the coolant heater with the coolant pump on. With the coolant circulating and the 220v heater on the temperature of the block appeared to go down a little.
I was using the passanger side block heater, and the temperature sender is on the drivers side.
I believe this was due to more evenly heating the block.

I am going to do another test today, seeing how long it takes to go from around freezing to 20'C the minimum recommended cranking temperature according to MAN diesel.

Starting temperature was -2'C (28'F) at 0900.
I would say the initial results are encouraging, already +1'C in 5 minutes that's an increase of 3 degrees C in 5 minutes.

5 minutes later, 13'C. Or increase of 16'C in 10 minutes

5 minutes after that, it reached the desired 22'C (68'F).

-2'C to 22'C in 15 minutes with out running the engine, not bad. Oh and this is with out the engine running, since I have an electric coolant pump.

Final test will conclude with a 20 minute measurement, because I am can.
Reading was 27'C after 20 minutes.
That's fast enough, for now....

I used both my 220 volt extension cords for this test to get power to the suburban. The 40 amp continuous 4/12ga with 10ga neutral and 30amp my 3/10ga cord, to reach 40 some feet.