Is it really bad for my 996TT to warm it up on the drive?

Solid black ice on the drive, 5am, minus 4. Car theft not a problem, gates, car blocked in and giant dustbin lid lock on steering wheel with seperate key in my sky rocket. Does it damage the engine left to idle as it warms up or is that an old wives tale? Ta

Without checking the handbook, I'm 99.9% sure it says that you should drive the car but keep the revs below 3,000 until warmed up

IMO leaving the car to warm up stationary should not damage the engine, unless your cooling system is buggered. Manufacturers have used the tack of driving straight off because they know that the engine is MEGA inefficient during the warm up cycle and they have to be seen as caring about mother earth, thanks to the current religious practice of beating our selves up simply because we exist. Fact of the matter is that most wear occurs during warm up & whilst driving off will ensure that the engine reaches temperature more quickly, this benefit could be quickly offset by asking the engine to work too hard before it is at operating temp. The loss of your car through theft would be more likely than the warm up damage you fear! The obstacles you have put in front of a determined thief would be merely a challenge for him!!!!

Re: Is it really bad for my 996TT to warm it up on the drive The reason given NOT to let your car warm up stationary is that the engine develops 'hot-spots' (areas that get much hotter than other areas of still cold metal nearby) - if the car is moving, the effect of air passing over/round the engine should help even these differences out. Clearly you don't want nearby areas of metal expanding at marked different rates. Gasket failure springs to mind. In case you are thinking 'so what about being stuck in a traffic jam?' - once warmed, the engine does not have adjacent areas with such a sharp temperature gradient. But it might all be bollocks.

Another reason (and this come from tuning EFI engines personally) is the mixtures you need to use when cold are a lot "wetter", fuel enriched. This tends to foul plugs, fill cats etc with a wetter unburnt mix. Engines that warm up at idle take far far longer to warm up than engines that are driven. The sooner you can warm it up the sooner the engine is running at good efficiency and hence burning off the cancerous pollutants. Don't forget your cats don't work until the engine it at full operating temp as they need to be super hot therefore all the chemicals they should burn off will be present in the exhaust until warmed up. So yes, it's a lot about catalytic converter care and efficiency than anything else.

Orangecurry:I must inform you that the 996 is water cooled, this is one of the reasons that the 996 was a vast improvement over the old fashioned 993 that anoraks rave on about. This means that air does not cool the engine directly, a water jacket takes the bi product of combustion (heat) away from the engine in a controlled uniform manner; whether the car is moving or not will not effect this at all. Don't forget, there is a thermostat which prevents the water circulating the engine from being cooled by the rads until it has reached a temperature such that the bi metallic strip in the thermostat opens and then allows the full cooling job of the rads to be done. I would also hint that the metals used within the internal combustion engine are good heat conductors - this means that hot spots are unlikely as the heat generated more locally (for example the exhaust valve) will dissipate down a temperature gradient - unless of course a build up of carbon (unlikely on modern 4 stroke engines) acts as a heat sink and creates the imagined hot spot. Jeff: if all works on the computer side the mixture should never be "wet", simply rich enough to aid combustion in the cold. As the engine warms so the computer will instruct the injectors to lean off. In any case the engine does not idle at tick over, and a 3 way cat reduces NO2 to N2 & O2, oxidises CO to CO2 & oxidises unburnt hydrocarbons to CO2 & water. It doesn't give a toss about cancer (although the unburnt hydrocarbons with the aromatic amides certainly don't need to be spread on your skin) and it reduces power. Whether a converter lasts longer in a car driven from cold might be an interesting project for somebody but I maintain that letting a car warm up on the drive would not unduly effect one's life - unless the car is nicked

I must inform you that I was talking about water-cooled engines in general when I made my comments. As it happens, it also holds for the oil-cooled 993 engine.

The comments I made were relayed to me many years ago, so as I have a few moments to spare, I thought I'd do a bit of trawling. Here's a slightly different angle on why it is bad:- Title - Engine parts the wrong size because the engine is at the wrong temperature. Next comes the bit when the engine is running but there are uneven temperatures in the engine causing uneven sizes. There are a few minutes when some bits are cold and other bits are hot, and you need to get out of this phase as quickly as possible. If you leave the engine running when stationary, it is going to warm up very slowly and you will stay in this phase for a long time. If you just drive off, then the engine does more work and you will warm everything up quicker. Leaving it to idle can also cause bore wash (not enough oil at the rings) and will glaze your bores. There is some wear in this phase - but it can get bad at high load or high revs. The water should warm up in 5 minutes, but the oil can take up to 15 or so. Manufacturers sometimes tell you to drive off immediately because of fuel economy, but I suspect that this is to avoid using the term "engine wear" in an owners manual.

here's some from someone who knows what he is talking about on a bike website. The best way to minimize all this contamination is to warm the engine as quickly as is reasonably possible. "Reasonably possible" includes placing a load on the engine by actually riding the bike. One or two horsepower are needed to idle an engine, but it takes 10 or so to go down the road. More horsepower develops more heat, hence, the heat from the 10 warms the motor faster, reducing corrosive oil and engine contamination. If you keep revs below half-way to redline and the throttle below one-half, you'll have no trouble with blow-by or overstressing cold and still loose parts. Long ago, before emissions standards and too many lawyers with time on their hands, General Motors learned that engines lasted longer if they were warmed by driving the car .

I usually give mine 2/3 mins standing still then drive off keeping the revs under 3k RPM until fully warmed-up...in the 993 this(warm-up) takes longer though at this time of year. :?:

As OC has stated, and having seen on this type of thread on many other forums (Mercs, Lexus etc) that to warm a car at idle only is worse than actually putting slight load on the engine whilst driving from cold. On a Merc forum, i was told the best way to treat a engine from cold is to let the car run from a minute or two, to get the oil round the engine, and then drive the car below 3k rpm until it reaches operating temp. Make sense to me, besides, im always in a rush to get to the train station in the morning! :roll:

My Lexus actually revs itself from cold immediately to a fast idle of about 2k for a half minute or so. I reckon start up, drive off, and drive gently until the oil has warmed through (perhaps a 997 owner with oil temp gauge instead of pointless battery condition gauge could tell us how long that takes...) as that way you're also warming through transmission oil.

... the thread question wasn't about which method of warming the engine was best but whether leaving the car warming on the drive would damage the engine, which I don't think it does...

Re: Is it really bad for my 996TT to warm it up on the drive Would seem that the correct way to warm the engine is to drive it from cold but if you occasionally want to warm the car up (rather than the engine) before you head off on a cold winter morning it's not going to damage the engine

I make every effort to keep revs below 2,000 until temperature gauge passes the 80 mark. This also means concentrating to minimise throttle loads & avoidance of too high a gear (same thing really) at low speeds. Is 3,000 a more sensible target which doesn't increase risk of damage? Peter