Wednesday, February 8, 2023


Engine heater failure: What we learned when the temps dropped

We were trying to outrun the weather. Bitterly cold weather was giving chase to our RV as we tried to escape the winter cold of Missouri. We’d made plans ahead of time but hadn’t counted on the cold weather coming quite so quickly. Our first stop on our 1,000+ mile trip south was in northern Mississippi. In a normal year, Mississippi temperatures would have been gentler on our diesel pickup truck. This year, the campground manager told us nighttime lows were forecast to be 19 degrees F. They’d had snow the day before we arrived. Yikes!

No problem! We have an engine heater…

Nineteen degrees meant our diesel truck would need assistance if we wanted to continue to travel the following morning. So, Hubby dutifully plugged in the engine heater, and we hunkered down for the night, dreaming of warmer, sunnier days to come.

Non-functioning outlet

The next morning, the truck would not start. It just wouldn’t! Upon further inspection, we discovered that the electrical outlet into which the engine heater had been attached was not functioning. It was a faulty outlet. It was also, as forecast, 19 degrees. There was no way the truck would start until the heater had time to do its job. We used an alternative outlet (that worked) but had to delay our start by more than two hours. As any RVer knows, a two-hour delay means the difference between parking and setting up in the daytime light or fumbling around an unfamiliar campground after dark.

Lessons learned?

What did we learn? First, it’s good to be prepared. It was a really good thing we had installed the engine heater on our diesel truck. However, when checking the weather forecasts, we’d only looked to see if winter storms were forecast for the areas we planned to travel. We hadn’t checked for temperatures. From now on we will. Also, when using vitally important equipment, we will check that the electrical outlet(s) are operational. It would have taken just a minute to test the outlet before trusting it to operate our engine heater. We assumed the outlet worked. We won’t make that mistake again!



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Dick Hime
1 year ago

Seems to me (I’m a retired ASE Master Auto Tech) that if you have a glow plug system on your diesel engine that it may not be functioning properly – or – you may not be using it correctly. Granted, it takes a diesel engine much longer to reach operating temperature after starting at that temperature but it still should start easily if: 1) the glow plugs were working, 2) you didn’t have water (or ice) in the fuel line, and, 3) you had sufficient battery capacity to BOTH cycle the glow plugs AND crank the engine at normal cranking speed. An engine heater (or tank heater as they are called) should not be a necessity for starting a healthy diesel engine at 19F.

Stan W.
1 year ago

Also,try in those circumstances, turn key on, wait for glow plug light to go out, shut key off. Repeat this steps 2 more times. then try starting the truck. Also make sure your truck batteries are in good condition. Sometimes if voltage is below a certain voltage (i.e. 12.4 volts) the glow plugs will not come.

Thomas D
1 year ago

Did you try starting the engine or did you assume it wouldn’t start . My chev duramax starts regularly in that temperature. Turn on key, wait until glow plug lights go off, start engine. No biggy.

Bob M
1 year ago

You can also buy a circuit polarity checker at Home Depot, Lowes or hardware chain. Than if theres power when you plug it in It’ll light up.

1 year ago

We went through minus-25 Celsius (minus-13 Fahrenheit) for a few days around Christmas. Diesel truck and gas car started just fine. Neither were plugged in. Both were parked without shelter on the side of the street. What did happen is a stone chip became a two-foot long crack in the truck windshield.

Being Canadian, I am more likely to plug in a battery warmer than a block heater – not yet, hasn’t been cold enough.

My concern this winter was that the coolant in the car only tested as good to minus-30 C. As a rule I like to see it good to minus-40 C (-40 C and -40 F are the same).

The thaw has started and the snow is sliding off the roof. Sounds like freight trains. Another one came down a little while ago and the walk needed shovelling. It’s Spring!

Tommy Molnar
1 year ago

I used to plug in my old diesel pickup during the winter so I could get to work in the morning. I knew it was working because it would dim the lights in the garage when I first plugged it in. 🙂

Neal Davis
1 year ago

Great advice! I always presume too much and your story reminds me to not do it. Thank you!

1 year ago

19 degrees overnight in Montana is close to summer nights. I’ve had a F-350 since 2010 and never have used the engine heater. The lowest for me was -34 and the truck fired right up; no garage with the wind blowing.

1 year ago

Any modern diesel will start at 19 degrees, must have been an older one without the glow plugs working.

1 year ago
Reply to  Neil

Ram doesn’t use glow plugs, they have heaters in the intake manifold. Either they have bad (weak) batteries or more likely the fuel gelled. Mine has started at those temps, once even without the heaters working

Seann Fox
1 year ago

When you plug in your block heater take a moment and listen. In less than a minute you should hear a sizzle as it heats the coolant. Some people just plug in a light to see if the outlet works however that will not let you know that the block heater is actually working. Listening for the sizzle does

1 year ago
Reply to  Seann Fox

Good to know. Thanks!

1 year ago

I used to plug my Toyota with engine block heater during New Hampshire Winters. Started every time, first time. Now, the Sun in Alabama does all the work.

Gayle V.
1 year ago

I keep an extention cord for plugging in my truck that has an LED light on the plug so I know the outlet is working when plug it in.
Secondly, my truck doesn’t need to be plugged in until the temps get down to about -10F degrees, (according to the owners manual). I’ve only ever plugged it in once, we were in Minnesota last February, it got down to -32F degrees.

1 year ago
Reply to  Gayle V.

Brrr! That’s really cold!

1 year ago
Reply to  Gayle V.

Do the same extension cord with lighted plug sockets then you know you have a live circuit.

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