Overheating while idling

[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 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!

[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.