Block Heater Questions - Diesel Forum

1987IDI · 11-18-2009, 10:31 PM

When you guys plug your trucks in at night, how does your temp gauge read when you start it?

My block heater is the factory, and was never once used until the truck moved to ohio about 3 years ago. I used to leave it plugged in all night, and that would be enough that around 30F the fast idle is not needed to start.

I now have it on a timer to come on 3-4 hours before i leave, and the fast idle is kicking on some mornings, and its not getting as warm.

A friend with a 7.3 could have full heat as soon as he started his truck, with temps in the teens.

Is my block heater warn out??

M.L.S.C. · 11-19-2009, 03:54 AM

The block heater's main purpose is to keep the engine from getting too cold - glow plugs may not even be needed to fire off, and oil is nice and liquidy and not the molasses it turns into at 15F so the starter is having an easier time as well, and there is also much less wear on the bearings and other internal components of the engine. Having comfortably warm air out the vents for the driver ain't a priority, it's nice but it ain't the primary purpose of the block heater. That said, it may be that you have a 500W heater, and your buddy may have the big mean 1500W unit. IIRC mine is a 1000W, at 20F I only need to have the truck plugged in for 3 hours and she starts off in low idle, but the air from the vents is still pretty darn cold.

I'd say don't worry about it, keep her on the heater for 3-4 hours as that obviously woks decent, and your electric bill won't go too high either. If you're worried about the heat in the cab, let the truck idle for like 5 minutes after you fire it up, and have the blower running on full blast with the temperature lever set on max heat and the vent selection lever set on max A/C - this will keep the outside air door closed so only air inside the cab is run through the heater core, and the A/C evaporator core will take away all the moisture in the air - I know it sounds weird to run the A/C on full heat, but it works, and they are actually designed to work together like that.