I,m with you I can tell by the wait to start light, some times the breaker will be tripped in the house and I wont notice but can tell in the morning by how much longer the light stays on.

My gauge has never read anything plugged in I have a real gauge in there now and it also has never moved till running down the road.

 

My water temperature goes starts at 100 degrees and I've never seen it move while having it plugged in. Even if it's plugged in for days I don't think it will get that hot.

 

I have an inline coolant heater that was given to me last winter but still haven't put in this style of heater may make the gauge move because it circulates the coolant while heating.

 

I wanted to let everyone know that my old block heater was not working. I tested the new block heater element before Mike (mcdavidson) installed it. The new element read 16 Ohms. The old element read 14.3 Ohms. I took another reading at the truck plug end. It now reads 15.5 Ohms at the truck plug. The old block heater element was definitely the problem.

A big Thank You to Mike for swapping that out for me.

I have the block heater plugged in on a timer set for four hours of "On" time. This is enough to move the needle from "Cold" to just under the "N" on the stock temp gauge.

I also have three glow plugs on the right bank reading infinity. I didn't bother checking the left bank. My back was acting up from the cold and having to lean over the engine. I didn't feel up to removing the intake hoses to make room to check the left bank. I think it's time to replace the GPs, anyway.

I highly recommend everyone test the block heater element. If it's reading 14.x Ohms, I bet it's not working.

If your block heater is plugged in for a few hours and your stock temp gauge is not reading higher than "Cold", I think your glow plugs are working well enough that the block heater is not needed.