Comparing engine block heater power outputs

[strelnik]

Hello all,

I have two CUCV engines, 1986 vintage, in my two military surplus G30 box trucks. backed by THM 400 three-speeds.

During this winter, both block heaters have died.

Understandable, since I think they are original. They pop the breaker when I plug them in.

My friend put a 400W block heater in the one and it starts the vehicle with no problems in -4 degree weather.

My question: I have seen a 1000W version of the block heater. Is this a better version? Necessary or good to have?

A guy who's a little bit of a know-it-all (no, he IS a know-it-all) says to avoid the 1000W versions because they burn out soon. When I asked him " How soon is soon?" he didn't know.

Out of curiosity, has anyone ever put in TWO block heaters, one for each bank?

Just wondering.

Thanks!

 

[tobyS]

He may be right on the 1000w. Higher heat elements CAN burn out if the heat is not getting away. If your position in the block has a very large water passage, a bigger element will warm it faster. At 400w on 120v it is using just under 4 amps, at 1000 about 9a. Two of the smaller would supply 800w, so would draw about 7+, could be used (most circuits are 15a) together, but I would not recommend two of the 1000 without special accommodation of the electric supply.

If one set up with 2 of the thousand, it would warm very fast but may subject it to improper thermal stresses. 400 worked for you before, put in a second of that size if you like a more even and faster heat (where in MI you may need it).

Had a discussion with a man that makes them run in Sparta and we concluded an electric blower with heated intake air elements would make a difference (and provide some positive air intake pressure under normal operation).