What should you do when you plug in the block heater at night but can’t plug it in again for another twelve hours during the day? Does this affect how the engine starts in the morning?
Just start it like normal. If you really need the block heater, then something might be off. Maybe you need new glow plugs, a better starter, or batteries. Unless it’s super cold, like -20°F, it should be fine without the heater.
I use a timer to have mine heat up for a couple of hours before I need it. Sure, technically you can start it anytime, but I like making it easier on my truck. These old trucks can be a little picky in the cold!
Just because it’s an old 7.3 doesn’t mean it should struggle to run. Get new glow plugs and a good glow plug relay, and you’ll be good. I started my 7.3 in Utah winters down to 0°F without plugging it in. It takes a bit longer to start, but it works.
Turn the key to get the ‘Wait To Start’ light to go off, then do it a few more times before trying to start the truck. I did this last winter at -10°F (forgot to plug it in) and it worked great.
Niko said:
Turn the key to get the ‘Wait To Start’ light to go off, then do it a few more times before trying to start the truck. I did this last winter at -10°F (forgot to plug it in) and it worked great.
You don’t actually need to do that. The glow plugs stay on after the ‘Wait To Start’ light goes out (up to 120 seconds). You can check by looking at the voltmeter; it’ll stay in the low 11’s while the glow plugs are on and go up once they stop. In cold weather, I let the glow plugs run for 30-60 seconds max, then crank it. Here are some tips that help my 7.3 start in the cold:
- New Motorcraft glow plugs
- New under-valve cover wiring harnesses
- Denso gear reduction starter
- Fresh batteries
- 200A glow plug relay (White Rodgers)
- 5w40 synthetic motor oil
If you absolutely need to plug it in, you could run a small generator before starting, or use a battery power supply that can run 1000W for hours. If you have power, plug it in to make things easier.
Luckily, I can plug it in at work…
I’m in Iowa, and mine starts at 20 below. It’s a little grumpy, but it starts. Use 5w40 synthetic if it’s usually below 32°F.
If it’s a really cold day, I try to take it for a cruise during lunch or run it at high idle for a while to keep things going. I once got stranded because of a bad relay, so now I always carry a spare. Treating the diesel at each fill-up helps too since I think the fuel lines are most affected by the cold.
Let it run for about 10 minutes. If it needs to warm up, it’ll go into high idle.
I find it easy to start if the day is warmer than the night, and I start it during lunch.
I feel like this question hasn’t really been answered yet. I’m curious to know what solutions people have for this.
How cold does it get where you live? A good set of glow plugs, batteries, GPR (I loved my stancor on my 02), and CK-4 rated 10w30 or 5w40 oil helps a lot for starting a HEUI in the cold. I’ve never had to plug mine in, even in the cold of SE Massachusetts.
Hi! I start it at lunch, or take a 10-minute smoke break every couple of hours. If it’s under 10°F, I do smoke breaks; above 15°F, I just eat lunch in the truck. If it’s above 30°F, I rely on glow plugs.
I’ve got the block heater on an RF switch and key fob, so mornings are easy. I also have a battery tender under the hood. My friend has 120v air heaters wired in too.
The biggest issue with my 120v system is the plug on the side, not the pullout direction of the truck. If I forget to unplug, it pulls the cord out smoothly.
Like the others said, replace your under-valve cover harness, glow plugs, and glow plug relays. Run 5w-40 oil and use stiction eliminator (Hotshot’s Secret or Archoil) and you’ll be fine.