Overheating while idling

[ayacucho]

2006 boxster. I was warming up the car in driveway for about 20 minutes as it hadn't been driven in about a week. When I got back in to put in garage the red warning light came on and the the temp needle went all the way to the left. Could the car overheat that way. Temp here about 30F.

[landrovered]

If the electric fans don't turn on then yes it will overheat at idle.

[Lil bastard]

Don't do that!

Idling for extended periods is very bad for the engine!

Your coolant and oil pumps (and consequently your coolant and oil flow) are RPM dependent.

Even if the fans are working properly, you're not providing enough flow to properly cool and lubricate the engine.

Prolonged idling is also very bad for the cats - expensive items to replace.

Cheers!

[landrovered]

I idle my cars until the temp gauge starts to move. Cold oil in a revving engine is far worse than in an idling one.

[Oaktown 986]

Originally Posted by landrovered

I idle my cars until the temp gauge starts to move. Cold oil in a revving engine is far worse than in an idling one.

agreed, but 20 minutes? that's a bit long...

[landrovered]

I don't think 20 minutes is too long, I mean, don't you think that Porsche would make sure that its cars could operate at idle without hurting themselves, it would be very poor engineering if that was not the case.

I think the problem is leaving it unattended.

I do not let my cars idle without watching the temp gauge because I have had too many Land Rovers whose clutch fans have failed. Just experience I guess. When we go offroad, I leave my truck running all day, but I keep an eye on it.

And how are you supposed to navigate city traffic without idling for long periods while stuck in traffic jams. It just makes no sense that you should not idle a modern EFI engine.

[yimmy149]

Whether or not you should warm up your car, it sounds like the original poster was just letting it idle and then putting it back in his garage.

Don't do that; you just load the oil up with nasty combustion by-products, and then leave them there to etch away the insides of your engine.

Buy a battery maintainer, only start the car if you are going to drive it for more than 30 minutes.

-james

[Samson]

Originally Posted by landrovered

I idle my cars until the temp gauge starts to move. Cold oil in a revving engine is far worse than in an idling one.

That's not really they best use of time or gas, plus in some cases leads to carbon buildup and/or cat problems. Just get in, start it up, and drive easily until it's warm. The engine, oil, and other stuff like the transmission that also need to warm up gets up to temp much much faster this way, not to mention the interior heat.

If you're really worried about it, give it 30 seconds and then go.

Also, just because the coolant temp needle is at ~180 or whatever you consider "warm" doesn't necessarily mean that the oil is anywhere near operating temp. I'm not sure on the Boxster, as I don't have an oil temp gauge, but my old VR6 would take about twice as long to warm the oil as it would the coolant. The Boxster has almost twice the oil capacity, so I'd assume it takes even longer.

[landrovered]

I used to subscribe to the 30 second thing until I read this.

http://www.ferrarichat.com/forum/faq.php?faq=haas_articles

It is a fantastic body of knowledge.

[70Sixter]

First WELCOME to ayacucho!

I would agree that long idle time is not advisable, but don't think the engine should overheat unless there is a problem.

Not sure how well modern cars handle rich idle control, but my -6 would get the cylinders washed down with excess gas if I did that long start up idle.

Check coolant level. Check for cracked plastic container as that is frequent problem. Wet carpet?

The check the radiators for blockage from leaves or street junk. Clean if needed. Remove front bumper cover to get at them easily.

Then check to see if the fans are operating. You can hear them running.

If that doesn't clear the problem and it over heats again, I'd take it to a good mechanic.

I have a rule that I run my car until it reaches operating temperature and then drive home for even an otherwise quick trip into town.

[Samson]

That looks like a good read, but unfortunately I don't have time to read the whole thing right now. I'll have to give it a complete look later.

I did give it a skim (a thorough skimming, but skimming nonetheless), and I still disagree with the warm up idea. Warm up before going WFO or even a bit heavy on the throttle, sure. It's not like idling your car in the garage or driveway for any length of time beyond the time it takes to get situated, put on your seat belt etc, is a practical way to get your oil circulating properly. On truly cold days, ok, give the oil a bit to move around, but beyond that, I don't agree.

[ayacucho]

Thanks for the help, I won't do that again. I waited an hour and a half and restarted the car and the warning light is still blinking. Manual says blinking light means low coolant. Coolant is full, no leaks. Not sure now, may have to bring to dealer to check. Once again thanks to all for the help.

[Lil bastard]

Originally Posted by landrovered

I idle my cars until the temp gauge starts to move. Cold oil in a revving engine is far worse than in an idling one.

The whole point to idling a car for about 30 seconds after startup is to allow the oil galleries to pressurize and float the crank. This is why the DME operates in Open Loop for 30 seconds, it then switches to Closed Loop operation to facilitate driving and controlling emissions. After the slight warm-up, you want the engine revving higher so that oil is flowed to the top of the engine and lubes and cools the head, cams and valves. The oil pump is not at maximum pressure or flow at idle, nor is the coolant pump.

Most of the caution about driving at low throttle until things warm is related to the transmission which does not produce heat from combustion as an engine does, but only warms from the friction created from it's internals by operating in gear.

Also, cold starts, and cold starts in cold climates, is exactly why multi-grade oils were produced and these work quite well. Excessive warm-up and idling is a thing of the past.

So far as Porsche engineering is concerned, your faith in it doesn't make it so. These are the same folks that brought you IMS and RMS issues (what are they on their 4th or 5th gen. fix?).

People believe what they want, I mean there's still a Flat Earth Society... but that doesn't make it so.

Cheers!

[landrovered]

Thank you for the advice.

Did you read the article that I linked to? The good Doctor makes it abundantly clear that the problem as he sees it is cold starts. If he is mistaken then I certainly would like to know about it.

You read and you read and you talk to folks and then you make policies regarding what you do and how. That is what I have done.

Hydraulic lifters like oil and they like warm oil. I realize that our German boxers are not V8s and am willing to change my policy if evidence is produced to the contrary of what is the basis for warming my engines.

Give me some data.

[Lil bastard]

Originally Posted by landrovered

Thank you for the advice.

Did you read the article that I linked to? The good Doctor makes it abundantly clear that the problem as he sees it is cold starts. If he is mistaken then I certainly would like to know about it.

You read and you read and you talk to folks and then you make policies regarding what you do and how. That is what I have done.

Hydraulic lifters like oil and they like warm oil. I realize that our German boxers are not V8s and am willing to change my policy if evidence is produced to the contrary of what is the basis for warming my engines.

Give me some data.

I don't want to get into a long dragged out discussion on this. Academically, some arguements look good on the face of it.

But one thing the 'good Doctor' is discounting are the millions of cars operated each day, including those in freezing climates, where most drivers pay little if any attention to warming from a cold start. And most of their engines operate well to the extent of their design life. And, for those which aren't, there are too many variables involved such as driving style, abuse, avoided or poor maintenance to point specifically to poor startup procedures alone. His 'theories' just aren't born out in real life.

If it were such a problem, the roads would be littered with cars with blown engines and this is just not the case. There is proof all around you.

Cheers!

[landrovered]

I think it is a case of "if the poison doesn't kill you the cancer will".

Wear occurs before the motor is warmed up at startup. We agree on that.

Cold oil is more viscous, I think we can agree on that.

The question is:

Which is worse for your engine, insufficient lubrication due to increased viscocity of cold oil, or the effects of inefficient combustion on your oil and catalytic convertor.

The lack of cars on the side of the road is not sufficient for me to change my views on this. The lack of evidence is not evidence to the contrary.

I have two cars that I have owned since new with over 200k miles on them on original engines.

[Samson]

Originally Posted by Lil bastard

After the slight warm-up, you want the engine revving higher so that oil is flowed to the top of the engine and lubes and cools the head, cams and valves. The oil pump is not at maximum pressure or flow at idle, nor is the coolant pump.

Exactly. The FerrariChat post mentions that after a certain pressure, thicker/colder fluid (oil) doesn't flow any more, which may well be true (I'm not big into fluid dynamics, sorry), but what is that point? I'd guess it would be above idle somewhere. Combine that with the other important stuff that needs to warm up, and we arrive back at the original conclusion to not let your car sit and "warm up".

And wait a second. The world isn't flat? Consider my mind blown.

[landrovered]

At the end of the day we may be arguing about 2-3 minutes difference between your 30 seconds and my warm up.

The thing I learned from the article is that pressure does not always equate to lubrication.

[Samson]

Originally Posted by landrovered

I have two cars that I have owned since new with over 200k miles on them on original engines.

It's not that it's going to necessarily hurt your car, but that it's just not needed with modern cars.

Anyway, hope the OP figures out the overheating/low coolant warning problem. Good luck.

[Lil bastard]

Originally Posted by landrovered

I think it is a case of "if the poison doesn't kill you the cancer will".

Wear occurs before the motor is warmed up at startup. We agree on that.

Cold oil is more viscous, I think we can agree on that.

The question is:

Which is worse for your engine, insufficient lubrication due to increased viscocity of cold oil, or the effects of inefficient combustion on your oil and catalytic convertor.

The lack of cars on the side of the road is not sufficient for me to change my views on this. The lack of evidence is not evidence to the contrary.

I have two cars that I have owned since new with over 200k miles on them on original engines.

I'm not sure we do agree at all.

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. It is quite literally akin to bearing starvation for a few seconds on each cold start. Bearing starvation on a track can destroy a bearing in just one turn, so you can imagine the cumulative effect this can have over time - it has nothing to do with the temperature/viscosity of the oil, only the absence of it.

And while cold oil may be more viscous, the question is more viscous than what? That same oil a few hundred degrees warmer? How much lack of viscosity is necessary for the oil to flow? What is the W on multi-grade oil mean? - That is the viscosity (or resistance to flow) of the oil at a certain temp - for a W0 rated oil, that temperature is: - 22°F and it's resistance is 3250cP. Compare that to a 25W oil which is 6000cP @ +23°F and you see what a tremendous difference it makes to use a multi-grade oil. And, in a multi-grade, this is the base oil - the addition of polymers means that the oil 'thickens' (in terms of resistance) as it's temp rises, not the other way round.

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.

If you have cars with 200k on the original engines - congratulations! You fall into the group of about 75% of all people with cars built after 1994 - 200k is now the norm for modern engines which have been well maintained. That is not unusual at all these days.

Cheers!