Overheating while idling

[mikefocke]

if, instead of sitting idling at 800-1200RPM, the engine and transmission were operated below 2500 RPM as you drive for the first few miles?

My Boxster now never goes out on cold days but when it did, it was a daily driver and took off slowly as soon as the seat belt was buckled which means maybe 15 seconds after start. The only time I ever idle to warm the cars I own are in snow, ice or fogged windows conditions where it is a matter of safety.

[Adam]

Originally Posted by Lil bastard

Wear occurs at startup - 85% in a 'normal' engine's lifetime. But not because the oil isn't warm, because all the floating parts - crank, cam aren't floating and because the other metal parts experience metal-to-metal contact until oil flows to float and/or coat or 'film' the other parts.
The question you pose isn't àperpot. It isn't a question between these things at all. You either experience normal startup wear alone,... or you add to it the effects of inefficient combustion on your catalytic convertor and the adverse effects of reduced flow of coolant and oil to the engine - the first is unavoidable (unless you have an electric pre-luber), but the second is totally voluntary.
Cheers!

I agree, I believe most of the wear occurs within a few seconds of startup and without a preluber system it is unavoidable. It can be minimized with a low viscosity multi-grade synthetic oil, but not eliminated. I personally let my cars warm up and idle for several minutes if it is sub freezing. The colder it is the longer I let it warm up and idle. Under a cold start in those conditions the car's ECU sets the idle higher, usually close to 2,000 rpm for awhile to get the oil pumping and engine warmed up faster I assume. This may be all wrong and pehaps I'm making things worse for my engine and exhaust system, but it makes the most sense to me so I do it, plus it's no fun getting into a freezing cold car. In regards to let it idle or not, in the end it probably doesn't matter much either way, people have their preferences and there is no clear right or wrong answer. I do think some of the push to drive off right away comes from the "green" camp who hates car emmissions thus can't bear to see a car idling away doing nothing but polluting the air. I believe this line of thinking has influenced the mainstream and "car people" alike.

Originally Posted by mikefocke

if, instead of sitting idling at 800-1200RPM, the engine and transmission were operated below 2500 RPM as you drive for the first few miles?
.

This sounds good in theory, but if you shift at 2,500 rpm then you are putting the engine in a very low rpm range essentially lugging the engine some which is a no no. The rpm difference between 1st and 2nd gear is about 2,000 rpm so shifting from 1st gear to 2nd gear at 2,500 rpm would drop the revs to aprox 500 rpm. Just playing the devil's advocate maybe, but it seems a lot of people are splitting hairs on this subject so I figured I'd throw that in there.

[stephen wilson]

I agree that you shouldn't let the RPM drop below 800-1000 while driving off, but you're not really lugging the engine as long as the throttle opening is very small. Lugging is created by a large throttle opening, with the resultant high cylinder pressures, at low RPM.
Steve

[Samson]

Originally Posted by Adam

This sounds good in theory, but if you shift at 2,500 rpm then you are putting the engine in a very low rpm range essentially lugging the engine some which is a no no. The rpm difference between 1st and 2nd gear is about 2,000 rpm so shifting from 1st gear to 2nd gear at 2,500 rpm would drop the revs to aprox 500 rpm.

If you're going easy on the throttle (as you should be during warm up), it is not lugging.

Shifting at 2,500/15 mph in 1st does not drop the revs to 500 rpm in 2nd. It drops them to around 1,500 in 2nd, and that's fine.

[Adam]

Originally Posted by Samson

If you're going easy on the throttle (as you should be during warm up), it is not lugging.

Shifting at 2,500/15 mph in 1st does not drop the revs to 500 rpm in 2nd. It drops them to around 1,500 in 2nd, and that's fine.

Originally Posted by stephen wilson

I agree that you shouldn't let the RPM drop below 800-1000 while driving off, but you're not really lugging the engine as long as the throttle opening is very small. Lugging is created by a large throttle opening, with the resultant high cylinder pressures, at low RPM.
Steve

After reading your guys' posts and thinking on the subject a bit I'm in agreement with both of you.

[Anim]

A few days ago my friend had his new second hand BMW 325 sat on his drive, he was set to head back to uni (engine running) when he heard the doors lock while he was saying his good bye's.

We spent around 20 mins trying to break into it as he didn't have a spare key, in the end we phoned an auto lock smith who said he could guarantee to get in it and be there fast.

The lock smith turns up and starts messing with the door lock, we notice that the temp gauge was rising towards the red.

The lock smith kept going back and forth to his van to try a different tool.

Then the smell started, like hot brakes.

We were saying "Break the window, turn it off" but the auto guy was like (ive nearly got it) them an alarm sounded, like a low pitch buzzing which was definitely a bad sign.

I shouted "break the window!" but he still didn't. He was running around the car hoping that the auto locksmith would win out.

Then there was a cough, a splutter then the car stopped and a huge amount of steam came out from under the hood.

10 seconds later the auto locksmith managed to open the door by using some kind of inflatable pillow in the door corner which allowed him to poke a stick into the car and hit the window release button.

We now know for a fact that the head gasket has gone which is a £400 fix and we don't know what else may have been damaged.

It was horrible watching his new car go from "oh ****************, the doors just locked" to a dead car.

I will never leave my keys in the car and shut the door now. No idea why his doors all locked too which is another mystery.

Anim

[Steve Tinker]

If your friend had rammed some rags up the exhaust tail pipe, the back pressure would have stalled the engine. But I know what you mean - you tend to panic when things spiral downwards.....

We had a rather strange (err unusual) guy working for our company 3 or 4 years ago. He drove a small Suzuki 4 wheel drive thingie to / from work. He was always carrying things - things like like raincoats, lunch boxes, news papers, plastic bags, etc.
He left the Suzuki as usual and went into the office to start the day - when he re-appeared 8 hours later to go home, he found that he had forgotten to switch off the engine The poor car had been sat idling in the parking lot from 0700 hrs to 1600 hrs. He just shrugged his shoulder and drove home....
Mind you, he was the kind of guy who believed that the car was serviced each time you filled up with fuel!! And you don't need to change modern oils either!!
As I said, he was a little strange.

[Anim]

Its interesting you should mention the rags, we tried that for a few minutes but nothing happened so he stopped. Maybe we should have persevered with it.

[Lil bastard]

I don't understand how that could happen to your friend because according to several here, it's not harmful to let the car sit and idle, unless of course they're incorrect.

Cheers!

[landrovered]

Man what a horrible thing that would have been to go through! I suppose I would have tried to pinch off the fuel line somewhere but would have probably ended up catching the whole thing on fire. It is funny that the cars that no one cares about can idle for eight hours without an issue and the nice ones self destruct. It is the way of the world I guess.

[Lobo1186]

Originally Posted by Lil bastard

I don't understand how that could happen to your friend because according to several here, it's not harmful to let the car sit and idle, unless of course they're incorrect.

Cheers!

so one car out of thousands which sit idle every day... and this is concrete evidence that idling is bad?

coming from NE ive left cars idling along with pretty much everybody I know for extended periods of time with no issue. I even left (by mistake) my car on all day while I went skiing... car still runs fine to this day.

[Anim]

Originally Posted by Lil bastard

I don't understand how that could happen to your friend because according to several here, it's not harmful to let the car sit and idle, unless of course they're incorrect.

Cheers!

I guess some cars can and others can't. You would have thought that a BMW would have some kind of over heating cut-off.

[Samson]

Originally Posted by Lobo1186

so one car out of thousands which sit idle every day... and this is concrete evidence that idling is bad?

coming from NE ive left cars idling along with pretty much everybody I know for extended periods of time with no issue. I even left (by mistake) my car on all day while I went skiing... car still runs fine to this day.

It's not that it's necessarily bad, it's just completely unnecessary, wasteful, and illegal in a lot of places.

The cars that overheat likely have cooling system issues that would have popped up somewhere down the line anyway. Any car with a properly functioning cooling system should have no problem keeping the car in spec at idle for a long period of time.

Really sucks about the BMW, but then again, they aren't exactly known for their quality cooling systems. Just the opposite, in fact... they have crap cooling systems that have a tendency to fail.

[Lobo1186]

Originally Posted by Samson

It's not that it's necessarily bad, it's just completely unnecessary, wasteful, and illegal in a lot of places...Any car with a properly functioning cooling system should have no problem keeping the car in spec at idle for a long period of time.

i guess that is my point right there... it isnt necessarily bad and a properly maintained car is fine. unecessary? have you had to get into a car in -30 degree weather? and illegal... never heard that but i dont doubt it.

[Samson]

-30? No, but -10 or so. In that case, I give it 20-30 seconds, and off I go. Warms up much faster that way. As for warming the interior, that's why they invented coats and gloves (and heated seats). In that kind of weather, the heat is warm within 3 or 4 minutes of driving.

That and people who live in places where -30 is commonplace typically have block heaters.

As far as it being illegal is concerned, it's not a law in too many places around here, but it damn well should be. Do you let your car idle at train crossings or in a stopped traffic jam? That's another waste. I prefer my gas to be wasted in the form of tire burning fun.

[Anim]

It is illegal in the UK it seems. Just googled it.

Edit: If on the public highway.

[landrovered]

The UK has a law against EVERYTHING!

But my car is not sitting still it is rotating with the earth at 24,000 miles per hour!

[Anim]

Originally Posted by landrovered

The UK has a law against EVERYTHING!

I know, thats why we all sneak about at night. Its to risky to be caught doing anything in the day.

[Lil bastard]

Originally Posted by Anim

I know, thats why we all sneak about at night. Its to risky to be caught doing anything in the day.

@ Anim,

Yea... must always be on the lookout for that proverbial Sheriff of Nottingham! LOL

Cheers!

[Lobo1186]

Originally Posted by Samson

-30? No, but -10 or so. In that case, I give it 20-30 seconds, and off I go. Warms up much faster that way. As for warming the interior, that's why they invented coats and gloves (and heated seats). In that kind of weather, the heat is warm within 3 or 4 minutes of driving.

That and people who live in places where -30 is commonplace typically have block heaters.

As far as it being illegal is concerned, it's not a law in too many places around here, but it damn well should be. Do you let your car idle at train crossings or in a stopped traffic jam? That's another waste. I prefer my gas to be wasted in the form of tire burning fun.

never had a block heater... car always started up let it sit while i put my gloves and hat on and away I went. personally i like tire burning fun and well idling doesnt bother me at all i guess i just make up for all the people trying to save the planet.