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.

[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.

[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.

[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.

[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.