A reader letter, from Mr P.Walsh, in response to my column on preparing for winter motoring in issue 383, creates the subject matter for this month ñ engine pre-heating. For decades (but alas, no longer) the noble British company of Kenlowe offered British motorists the facility of after-fit 3kW coolant heater units, with pumped coolant circulation, to be fitted into the engine cooling system. After around 2 to 3 hours plugged in, engine start-up would be easy, given a good battery, and the almost instant circulation of warm coolant greatly assisted clearing frozen and misted windscreens and other windows, and faster warm-up of the cabin heater. In today’s pollution conscious world, there would be significant reduction of cold engine emissions, and probably much reduced risk of problems with exhaust gas recirculation valves clogging up in cold weather motoring.

So how do they get on in the really hard winters of colder climates, like in Norway, Finland, Canada, Russia, and colder parts of the USA? Well, they often get what are called ìengine block heatersî that employ electric heating elements located in the upper part of the engine crankcase, or in the cylinder head, and such items are either standard fit equipment, or relatively affordable options. Not only does that approach allow you to pre-heat your car before you set off on a cold morning, using a power lead from your home or garage, but also when you’re out on the road, perhaps for a meal in the evening. Places like shops and restaurants provide on-street or parking lot plug-in power supplies, much like those on caravan sites, and are now used for charging electric cars and plug-in hybrids. This is so your car doesn’t freeze up totally, like it might when it’s really cold in sub-zero temperatures, and there’s a much-lessened danger of the coolant freezing and causing severe engine damage. The heat provided in critical areas also helps reduce engine wear by assisting fast oil circulation, helps avoid diesel fuel waxing and fuel system blockages, although in some severely cold countries, electric fuel filter heaters and electric pad heating of the oil sump may also be used.

But in the UK, the primary benefits, all-year round, could be the significant reductions in emissions, which are known to be high when the engine is first started up, and in continued running, in more severe conditions. Cold diesel engine NO_x emissions can be up to 30 per cent greater than those of a warm engine, and up to five times greater in petrol engines. University of California studies showed that the emissions during the first 30 seconds after a cold start could be as great as the total emissions from over 50 miles of motoring with a hot engine. The situation with diesel engines applies primarily to particulate emissions, when particulate filters are not warmed up to their fully effective working temperature, and similarly with SCR (Selective Catalyst Reduction) systems, although much work has gone into improving the heat-up of such units to help meet recent tighter emissions limits.

It almost goes without saying though that fuel consumption is also significantly greater with a cold engine. Apart from lower engine efficiency, lots of heat from the fuel is being used to heat up that vast bulk of metal that composes the engine and transmission. The U.S. Environmental Protection Agency estimates that a drop in ambient temperature from 24 to 7 degrees Celsius increases fuel consumption in urban commuting by 12 to 25 per cent. It seems a great pity then that manufacturers have not taken the opportunity to offer in the UK those pre-heater systems that are often standard, or are available as options, on the very same models and engines sold in colder climate countries. This is all not too helpful for British motorists, who can only source branded quality imported heating units (such as from DEFA in Norway) and have them fitted or, as with our reader, buy any one of a number of imported heater units advertised on eBay, and find a helpful independent garage, or fit it with your own DIY skills. Then you face the problems and risks of modifying a car that is still under manufacturer warranty, and maybe even insurance issues with a modified engine. A disappointing conclusion maybe, but considerable food for thought.

Victor Harman