Drivers who warm their car up on a cold morning

[Geordie Mike]

I don't buy that either - water is the coolant, so it has to be colder than the thing it is cooling (it's impossible for it to be hotter). Water also has one of the highest heat capacities going (hence it stays hot for ages) - oil will get up to temperature much faster than water (why its used in oil-filled radiators etc.). If your coolant is at 90 deg C, your engine (and your oil) is going to be hotter than that, not colder?

Mike

 

[silver75]

Love the way folk get lulled into these arguments with Andymac

Ive seen the guy argue for days about anything from Big Brother to the Pope

 

[AndyMac]

Mike, it's the other way round, which was my point. If you have an oil temp gauge you'll see it climbs a lot slower than the coolant temp, and gets hotter than the coolant when at full operating temp, around 100-105 degrees. So using the coolant temp to judge whether the engine is at operating temp is not totally accurate, you need to wait another 5-10 mins for the engine oil to catch up.
Silver - not my fault no ones up to the job! I just like a good debate.
If someone puts a good case together based on facts (and actually uses the queens english to do it) then I'll be the first to concede. If someone puts forward some daft opinion based on tabloid propaganda or just plain stupidity I feel it is incumbant on all of us to put them right, or at least make them look stupid.

 

[ChriS3]

I have a great button on my car's alarm fob. It's called remote start. I can sit in my kitchen drinking my morning coffee, push a button and know that the car will be semi-warm and half lubricated by the time I get to it.

I don't run the car cold. I have it serviced every 3000 miles and flushed regularly so I don't worry about soot build-up, and the engine will be rebuit soon so I'm not concerned about engine wear

 

[smitch]

If someone puts a good case together based on facts (and actually uses the queens english to do it).

I just love the subtle digs that instigate the replies.

 

[smitch]

semi-warm and half lubricated by the time I get to it.

Be good if birds had a button like that...........

 

[jcs356]

I have a great button on my car's alarm fob. It's called remote start. I can sit in my kitchen drinking my morning coffee, push a button and know that the car will be semi-warm and half lubricated by the time I get to it.

Better not leave it parked in gear then.

 

[smitch]

JCS356

Is your Speedster yellow???

 

[AndyMac]

Be good if birds had a button like that...........

They do, it's called shopping!

 

[smitch]

folk

Haven't used that word for ages, good vocab.

 

[benw123]

Mike, it's the other way round, which was my point. If you have an oil temp gauge you'll see it climbs a lot slower than the coolant temp, and gets hotter than the coolant when at full operating temp, around 100-105 degrees. So using the coolant temp to judge whether the engine is at operating temp is not totally accurate, you need to wait another 5-10 mins for the engine oil to catch up.

Something we agree on then Andy. Oil does indeed take much longer to warm up than coolant. My previous car was a Focus ST170 which had an oil temp gauge, and that wouldn't start moving along its scale until well after the coolant. Would only start using the full performance after then.

 

[Geordie Mike]

Fair enough then.

 

[benw123]

Does it not take exactly the same amount of fuel to reach a certain temperature (ignoring the differences in efficiency at differing operating points for the engine)? So it doesn't matter if you're idling or doing 70, it takes the same amount of fuel to reach x deg C, which involves burning y ccs of fuel, depositing z mg of soot either way?

Not quite. An engine working at higher revs or, in particular, under load, will generate more heat faster than one at idle. And because it generates more heat, it warms up more quickly, and this in turn means it will use less fuel because the engine operates in its cold cycle for a shorter period.

I can assure you that if you start your car from cold and let it idle for five minutes, it will probably only be as warm as starting and driving it for around two minutes. This isn't speculation either; when I used to do oil changes on old Fords I used to run, I'd drive up to the end of the road and back again (warmer oil drains more easily), and the engine would already be very hot to the touch.

 

[Geordie Mike]

Yes, but it uses more fuel in order to get up to that temperature faster does it not? Therefore producing more CO2 & soot faster, but possibly still (about) the same amount? I know it will heat up faster, but I'm wondering if it will use significantly less fuel in getting to that heat faster, in which case there is less soot/CO2/whatever. If it doesn't, then it doesn't matter how quickly you heat it up, you're going to get (about) the same amount of soot deposited until you are at the correct temperature.

 

[benw123]

Yes, but it uses more fuel in order to get up to that temperature faster does it not? Therefore producing more CO2 & soot faster, but possibly still (about) the same amount? I know it will heat up faster, but I'm wondering if it will use significantly less fuel in getting to that heat faster, in which case there is less soot/CO2/whatever. If it doesn't, then it doesn't matter how quickly you heat it up, you're going to get (about) the same amount of soot deposited until you are at the correct temperature.

I understand what you're saying, but from cold the fuel/air mixture is very rich and will remain like this for longer when idling, because the car takes longer to warm up. Drive off, and while you will indeed use more fuel than just idling, the extra work from the engine generates more heat to end the cold start procedure sooner and the mixture becomes leaner.

Remember, even if you've warmed the car up, you've still got to drive away and complete the same journey using a similar amount of fuel.

 

[Geordie Mike]

Yes, that's fine. What I'm getting back to is the soot deposition only.

I accept that

a) you will use more overall fuel if you have your car on for 10 minutes before you complete the exact same drive
b) the engine will warm up faster the more work is done in a given time

What I don't buy into is that there is a difference in the amount of fuel required in order to heat that engine up. It requires the same amount of energy to reach temperature x degrees while the engine is operating in it's cold range, so the deposition of soot on the spark plugs is independent of whether the engine is idling or mid-range. The only place the engine can get the energy to heat up from is the fuel. It takes the same amount of fuel either way. One of the original points was that you get more soot deposit by idling to get up to temperature than by driving away from cold.

It's like a 2 kW kettle or a 3 kW kettle - both will boil 2 litres of water using the same amount of energy. The 3 kW kettle with do it faster, but use more energy getting there. You still get billed the same though.

 

[AndyMac]

The supposed damage to the engine is dependent on so many other factors this idle/warm up issue is almost irrelevant.
Which car will be in better condition:
Low mileage car that does the school/shopping run every day, round trip 6 miles, no warm up.
Higher mileage car that does the frosty warm up on the drive then blatts down the motorway every day at 70mph.
I know which one I'd prefer. It amazes me that people (even on here) are put off by high mileage cars and would prefer an older vehicle with low mileage.
Low mileage yes, but mileage that's very hard on the engine.
I had to do the school run this morning (6 miles round trip, no warm up) and although the coolant reached 90 degrees, the oil was only just registering at 60 degrees when I got back home.
Do that every morning and your engine will wear quite badly, so all in all I'd say the frosty warm up on the drive is preferable and better for the engine even if your driving a short journey in rush hour.

 

[Beerzo]

I love it when you here someone trying to start their car specially on cold days and its ticking over then it bursts into life then they rev the tits out it for a second or two. Your like what the f**k are you doing!
#

 

[smitch]

The boys in our workshop do that.

They get in their cars at the end of the day, fire em up then rag the **** out of it down the road like they're at ******* Santa Pod.

And we call em engineers?!?!?!?!

 

[benw123]

What I don't buy into is that there is a difference in the amount of fuel required in order to heat that engine up. It requires the same amount of energy to reach temperature x degrees while the engine is operating in it's cold range, so the deposition of soot on the spark plugs is independent of whether the engine is idling or mid-range. The only place the engine can get the energy to heat up from is the fuel. It takes the same amount of fuel either way. One of the original points was that you get more soot deposit by idling to get up to temperature than by driving away from cold.

Soot is a separate issue to engine temperature. Soot on spark plugs is caused by a rich mixture. In older cars with carburettors, if they were incorrectly adjusted you could end up with sooty plugs after a few thousand miles (ever see that page in a Haynes manual with all the spark plug pictures?). However, in modern cars with ECUs and fuel injection, the only way this is going to happen is if the car is left idling for extended periods, particularly during the ECU's cold start procedure.

The mixture has to be rich to overcome the extra friction from cold and make the engine turn, because the throttle is closed at idle. However, when you drive away, you're opening the throttle all the time and the mixture will become leaner.

 

[Isoproturon]

Quite apart from the theft issue, leaving the car unattended with the engine running is an offence.

 

[tjm69]

Remember a mate doing it after a nightshift, 5-30am frosted over starts car shuts door....couple of seconds later car locks itself.
He'd got a clarion or toad alarm fitted and it was tempermentle thing that locked it to stop you being car-jacked.
by the time he'd got a lift home got spares got back to work the thing and run out of fuel.
god did we take the **** next night lol

 

[EssVier]

Nope I just press the remote in my car and drive out of garage and away to work.

YEEHAA! Just thought, this is the first year as being a home/garage owner, so no more icy starts!! That is until I cany be ***** to park it in the garage overnight!

Roll on winter!

 

[craigynett]

Nope I just press the remote in my car and drive out of garage and away to work.

Just like me

Well, provided I go out in the Evo that is. Not quite enough room in their for me Fiesta or my g/fs A3!! If it freezes over whilst at work I start the engine whilst the windows are getting warm water treatment. Air con & heated front & rear screens sort the inside of the windows I'm usually driving off within 30 secs of starting the engine.

If i'm going out in my Fiesta I start the engine, give outside of windows warm water treatment & sit in the car till the blowers have cleared inside of windows, which can be 5mins sometimes.

My g/f wipes the inside of her windows with a cloth. I NEVER do that. Can't do with all the smears etc. Especially when the sun comes out. Can't see ****** all cos of the smudges etc.

If I was too bothered about CO2 & fuel costs then I wouldn't have bought an Evo. I'd buy 1 of those crappy electric things!! But seeing as tho i'm not a tree hugger I happily live with the fact I get about 25mpg on a good day & on a fun day about 10mpg


Craig

 

[audi80sport]

i would love to have the option to warm my car up before setting off but its a alarm goes off...snooze...alarm...snooze...alarm...OH SH!T B@ll@cks F&£K run to car drive off while clearing the windscreen with a demister pad getting blinded by the sun lol completly different subject but who ever invented the snooze button? why do they put it on alarms? you set it to get you up at a specified time. you wouldnt have one on your fire alarm would you!!!???

 

[jojo]

Snooze button = 5 minutes extra sleep, a godsend to some, but yes, I agree that most of us abuse the thing too much haha.