Starting Diesels on Cold Mornings

Hi Folks,

I have a VW Golf TDI, with 2 glow plugs that are not quite right, so my little car is sometimes hard to start when it's below zero (F).

Last night we were expecting -10 -15F, so I tried the following (on the grid location):
> 15 watt CFL in an extension cord work light
> Piece of 1" foil-faced foam (about 3' x 4') left over from house construction
> Old ripped blanket and small plastic tarp (usually used to keep frost off the herb beds)

I parked the car outside, near the garage door on the barn with a little snow on the ground, which also reflects heat up. I'm sure inside the barn would work better and would greatly reduce the cooling from wind currents, but would require moving a lot of stuff to get the car in there! I slid the insulation under the car to reflect heat upwards to the engine, and then slid the light between the insulation and the rear of the engine -- it won't fit right under oil pan because there's not much ground clearance under there! Then I placed the doubled-over blanket over the engine (not hot from running), and covered that with the tarp, also folded in half. This tarp is silver on one side and green on the other, and I used it with the silver side toward the engine, and closed the hood to try to hold the heat in. I turned the light on around 10 PM, and left it until about 8 AM (energy consumed = 15 watts x 10 hrs = 150 watts)

Actual AM temp was about -12F, and the expected high temp today is only about -5F and breezy (BRRRR!). The car started reasonably well, but still acted like it was cold, which is a lot better than not starting at all. Be sure to remove the blanket and tarp first so they don't get caught in the belts and fan!

Tonight is expected to be a little colder, so I might switch to a 26watt CFL, or maybe even use a 20-40 watt incandescent, since they will produce more heat.

I'd like to consider other options that don't involve live flames, or flammable stuff like a pan of glowing coals. My dad used to have an old kerosene heater for his antique 1914 Model-T which would hang on the bottom of the engine somehow, but that's like a kerosene lamp in a tin box instead of a glass chimney, and I don't want to light the car and the barn on fire! Maybe a piece of soapstone heated on the woodstove like a foot warmer would work better, and would use no electricity at all... Hmmm... Ideas?

buy a block heater. they thread into the block and heat up your coolant. they're almost all 120 volts, so they plug right into any old outlet or extension cord. smallest I've seen was 750 watts, and the largest was 2500. I think the one I've got is 1500 watts. that's a lot more energy consumption than your 15-watt light bulb, but it will all be heat going to where it will help instead of a lot of it being light with most of the heat ending up where it won't do you any good.

an outlet timer allows you to start heating it up an hour or several before you typically leave without having to wake up early to plug it in or leave it plugged in all night.

another option that will help is an engine blanket. that would do the most good in conjunction with a block heater. they're typically purpose built products that have a bit of insulation and are faced with shiny mylar-ish stuff to reflect heat back toward the motor. they also help the motor warm up faster once it's started. if you're really ambitious, you could rig one up for under the motor, too.


one of the most effective and energy efficient option that I'm aware of (short of parking it in a garage) is also the most expensive. there are a couple of European companies that make diesel fired circulating coolant heaters. they burn a very small amount of diesel for heat and there's a small pump to circulate the coolant which very effectively warms up the whole block. unless you find a hell of a deal, expect to pay over $500 for a used unit.

Hey Tel,

Block heater is a good idea, and I used to have them on former car engines, so I know they work great. The idea of putting one on a timer is an excellent idea that takes some of the sting out of a high-wattage solution. Probably can't afford a block heater right now, and I figured we might discuss some other less energy intensive options, especially for off-grid or very low energy households..

Making room to park it in the barn does make a difference in cold starting, and removes the hassle of clearing snow and ice off, too! That I gotta do -- at least for my wife's car. We heat with wood, and soapstone bed warmers do show up at local auctions every now and then, and that could be a good $4 solution (along with an engine blanket of some sort).

Another good idea occurred to me this afternoon when I came across an electric heating pad that we have used for pulled muscles, etc... Have to put it on a kWh meter, but it probably draws something like 60 - 75 watts. I could figure out a way to push that right up against the oil pan (maybe wrapped in burlap so it doesn't get filthy, and I'm sure that would work (though my wife would not be amused). Today I picked up two 40- and two twin packs of 60-watt incandescent bulbs for a total of $3.65, in part because I need a 40 and a spare for a lamp in an insulated box that keeps the water pipes above freezing in our former house (my future woodworking shop), and wanted to try the 60-watt for the car. The 60's would probably do the diesel job pretty well when parked in the barn (out of the wind), with a reflector below and a reflective blanket wrapped around the top of the engine, especially since they put out almost 95% heat, and only about 5% light.

Thanks for the ideas... I'll keep trying very low-cost options until I can afford to install a block heater on a timer.

BTW: this morning's temp was -22 just outside the front door, and -26 down in the hollow at the end of the driveway, and having done nothing to warm up the TDI, I didn't even try it today... I just hate starting a diesel when it's that cold -- poor thing sounds like its in pain!

any wrecking/salvage/junk yards nearby? new block heaters can be had for under $30, so I would imagine snagging one from a salvage yard would be pretty darn cheap. that doesn't help the off-grid situation much, I guess, but energy is energy. it's going to take some minimum amount of energy to do the job, and a block heater is very effective at delivering that energy in the form and location it's needed.

you could substitute a mylar emergency blanket (or a couple) for the motor cover. you would want to be sure to pull it off before you started it up, though.

tel, a Big Thanks for letting us know about the diesel fired circulating coolant heaters...i had no idea they existed, now that i know to look for them i've even found a propane one..

expensive, but i think cheaper than buying enough battery and solar panel to run a block heater, even if it's just for an hour or two...

this could open the door again for me to start thinking about biodiesel or SVO, I had written it off because of the starting issue and was resigned to keeping a gasoline engine truck... thanks

(Ben, there are a bunch of old timer methods, but they are more than a little sketchy and it might be real false economy to go there so i'm not going to mention them. It sounds like you don't want to burn down the barn. A bit of ether / starting fluid can be your friend when used in moderation. Make sure you don't get stuck with a tank of summer fuel in your vehicle if there's an early cold snap...not sure when they switch over down where you live. I have heard of people draining their crankcase oil and heating it gently over the woodstove in the wall tent...desperate times, desperate measures. Warm batteries help too with a bit more cranking power...there are plug in battery warming pads here, but a lot of watts again...also in conjunction with the block heater, some people use a magnetic heater that sticks to the oil pan. I'm with tel, if you've got electricity a block heater shouldn't set you back too much and is going to do the job...brrrrrr)

As a farm kid, we had all kinds of tricks to warm old diesel tractors and trucks off-grid (parked in the field).

Heavy wool blankets over the hood will hold the heat overnight. Make sure to cover the wheel wells, grille, and the back edge of the hood next to the windshield. Preferrably all the way to the ground.

We used to light a small oil lamp under the "tent", but probably not a good idea under a VW. That is a barn burner idea, and not in a good way.

I have a friend that has an SVO conversion on his F250, not for veggie but to be able to run summer blend year-round. He puts straight #2 in the SVO tank and #1 + anti-gel additives in the diesel tank, no worries even in NoDak.

You would be better off with a small incandescent bulb instead of the CFL, you don't need a lot of watts--maybe 25 or 40--but it does a better job of heating.