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Using Light Bulb to Keep Engine Warm

I have a 1978 GM 4x4 van with a 400 small block. In Denver we’re in a middle of a very cold (Polar Vortex) night that may get to 10 Below zero.
I have enough antifreeze to 10 below zero–nothing more and I’m a bit concerned. It’s about a foot too tall to get into the garage, so I’ve put a 60 watt bulb on a drop light under the hood about 6" from the engine block. Will this work, or do I need to get to the parts store for an engine warmer? I’ve also moved it up against the garage door. Any suggestions?

You need to get to the parts store. The light bulb will be useless.

Moving it up against the garage door was a good idea because if the radiator is protected from the wind it’ll take a lot longer for the engine to be drawn down by the wind to the ambient temperature. “Chill factor” is actually a way of representing the rate at which temperature dissipates, and facing the wind will chill an engine much faster than facing the garage.

I’ve heard of people successfully covering their engine with an electric blanket too, but that’s only a one-night emergency adaptation. If that electric blanket shorts, you could have a fire. I have to admit that I’d use one in an emergency as a temporary measure after my engine had cooled to the touch… including the exhaust manifold, which in my case encapsulates the cat converter.

If the antifreeze tests down to -10* it will not freeze and crack the block. Any significant blend of antifreeze will prevent cracking the block in fact. But if you start the engine with the coolant frozen like a slushy the engine will overheat due to the radiator being blocked. And if there is only a minimal of antifreeze in the mix a temperature that low would likely push out some freeze plugs. And a light bulb won’t make any difference unless the vehicle were parked inside and very little difference even then.

We rarely have extremely cold weather down here in Mississippi but when we do a great many people get caught unprepared. I have opened many radiator caps on overheated engines when the temperature dropped to zero and found green slush but have never seen any cracked blocks that resulted from the green ice. Once a radiator’s top tank was pushed off the core, though. With little or no antifreeze the damage can be catastrophic.

Agreed; a 60 watt bulb is near worthless and if you’re good to 10 below you should be fine anyway.

If a lamp is used you might consider a heat lamp. Those work very well and are pretty cheap.
Ideally, it should be placed on the ground underneath and facing the oil pan from a foot or so away. The heat should radiate upwards. Do NOT place a heat lamp inside the engine compartment.

Well, I still have the bulb right over the manifold and I went to the store and bought a magnetic engine warmer and attacthed that to the block. My garage is sandwiched in-between two residences like row homes and stays about 25-30 degrees above the outside, so it’s radiating some warmth as well. I’ve changed the engine out once when this van hit 274K miles. It was still running great at that mileage, but when trying to make it up the mountains, it was just too weak. However, at my age today, I don’t want to change out another engine. Getting too old for that.

THE SAME MOUNTAIN BIKE? At 59, I’m still a avid bike rider. We have some of the best trails in the country in Colorado. Even in the city (Denver) and the southern burbs offer great trails, even with a 20 yar-old mountain bike.

Thank you for all your help.


Sounds like you have a good head on your shoulders and are making good decisions. Yo’ll be fine.

Yeah, I was hardcore through my 40s, and loved every second of it, but medical problems have eliminated cycling as an option for me. It’s even getting difficult to walk, and a few months ago I lost the use of my legs completely. I’ve gained most of the function back, but walking is a strain even with a cane. I have degenerative disc disease and a bum ticker (two heart attacks). Hey, I wouldn’t trade a moment of it.

I now live vicariously through my son, who rides on the west coast. Lots of slick rock out there.

I’ve been lucky! 10 years ago I had a small spot of lung cancer found in it’s infant stages–about the size of a postage stamp. They removed the lobe and I’ve been great. However, this summer my primary doctor wanted a follow-up cat scan on my lungs and they found two small heat aneurysms. Fortunately, one is only 4cm and the other is 11cm. My first artheroscopic procedure is next month for the small one, then a month later for the larger one. It was just cases of being in the right place at the right time. Biking is my getaway from everything. I’m sorry I won’t find you on the trails anytime soon. But, I’ll remember your riding when I’m out there next time–of course, that won’t be this week–too cold!

I lived in Indianapolis , IN when I was young and my parents would send me out to start our car at 2 in the morning and let it run for 20 minutes during the winter so it would start in the morning. Child labor at its finest.

So why not buy a gallon of Prestone and be done with it?

It’s been below zero all day and Monday I put in about a gallon and a half, but it still only tested to 10 below 0. I’m just being cautious.

Hey Volvo! That was child labor (torture!). I’ll not be going out at 2:AM. I’ve done all I can do with it for this cold front.

William, I’d be honored. I’ll think of you out there.
Ride carefully… don’t hit any deer, like I almost did. I was on a great descent, tires barely touching the singletrack, he was spooked by something and running across the trail.

But that’s a different forum… :slight_smile:

That’s what I used to do during school in Sioux Falls. When it would get that cold out, I’d get up at 2 am and go start the 59 Pontiac and drive it around a little. Then back to bed. Otherwise it would never start in the morning. Agree the light bulb will not do much. The magnetic heater will heat the oil but don’t think it’ll do much for the anti-freeze. Really though in Minnesota, all that is usually used is a 50/50 mix, and that protects well below -20. Maybe it just hasn’t mixed enough and needs to be driven more.

In North Dakota we plugged them in at night. Apartments there come with assigned parking spots, each with a 115V socket on a post and a switch inside the apartment to turn the socket on & off. In the barracks, we ran long extension cords out the bottoms of our windows and stuffed the resulting slot in the window with towels.

Your vehicle should start without problems if your battery is in good condition and your oil is of the correct viscosity. Here in east central Indiana, I started my Ford Maverick which was sitting outdoors when the temperature was -24 degrees. The crankcase had 10W-40 oil. I had no engine heater. I have started my 1978 Oldsmobile Cutlass when it sat outdoors in temperatures as low as -22 degrees. I did not use any kind of auxiliary engine heater. Both of these cars had a carburetor and the Maverick had the old distributor point ignition.

Put a remote starter on it. Hit the button from your bed.

I would drain and replace the coolant with a 50/50 mix, which is good for -34F.

While I support and use a 50/50 mix, -10F really isn’t that terribly cold. As Triedaq said, if your engine is maintained and in good shape, your battery good, and your oil of the proper viscosity, you should have no problem in -10F.

My comments were really geared toward -40F and sometimes colder, with chill factors of -70F and below (which means that if you park facing the wind your engine will be at -40F post-haste). The temps you’re facing where you are are damn cold, no question, but really aren’t that extreme for the car. I do recommend that you let the engine warm up some before driving off, however, to get the defroster working and to give the fluids a chance to loosen up a bit.

Actually I feel a 60 watt bulb can do a decent job of protecting a motor from freezing, but the OP is in a tough situation. I use a 60 or 75 watt work light to keep my inboard motor protected if I haven’t had a chance to winterize it before a cold snap. Now the temps in my situation are more like low 20’s, nothing close to a -10. And the inboard motor casing is padded fiberglass and helps retain the heat. In the OP’s situation perhaps a good foil coated insulated blanket over the motor with a strategically placed 60 watt bulb would protect the motor. Most car and truck motor bays would allow too much air circulation to retain heat without some additional insulation.

Remember Robert Gift and his floodlight?