Idling... Why is it so bad?

Messages
121
Location
Indy
I know excessive idling is bad for an engine, especially in cold temps, and know that the issues are condensation and fuel wash on the cylinders. What I don't know is why idling is any worse than driving in cold temps. Faster warmups, OK I buy that but if so, is it just that the first 10 minutes of idling is bad, but once the engine warms up it's no different than driving, wear wise? Is an engine running at a constant 800 RPM wearing faster than one running between 1500 and 3000? I ask because of having a remote starter. Nice to have this time of year, but obviously results a quite a bit of idle time. Thanks...
 
Messages
2,794
Location
NM
The problem is not engine wear, it's the oil taking a beating. An idling engine shouldn't wear nearly as fast as one that's under load and higher RPMs. Rick
 
Messages
3,593
Location
Outside smalltown, IL
I don't buy this whole "idling is bad" thing. I think it's a problem from a bygone era. A modern fuel injected engine has little if any excess fuel to worry about, and as long as the engine has adequate oil flow to the top end and pressure to the bearings I don't see how it can hurt it to run with no load...
 
Messages
1,381
Location
Southeast Kentucky
I would think that the problem with excessive idling is that the odometer isn't giving you a true picture of how long the oil has been used. You can idle for a month and show zero miles. That's why big trucks and heavy equipment have a gage for total engine hours used and a maintenance interval for hours OR miles, whichever comes first..
 

Patman

Staff member
Messages
22,012
Location
Guelph, Ontario
quote:
Originally posted by mrhonda: Toronto people, are the cops still giving tickets if you idle for over 3 minutes? Or did they suspend that for the winter months? [Wink]
In extreme cold they won't ticket, but all other times they still do. I got 1% fuel in my oil last winter, even though I would only idle my engine for 1min at the most on the cold mornings. That's too much fuel for me, so this year I now plug in the block heater, and leave within 10sec of starting the engine.
 

Al

Messages
19,256
Location
Elizabethtown, Pa
Well more moisture will form bc the actual oil temps are much lower. There was an SAE paper (2000-01-1073) that gave oi sump temperatures on a V-8 Chevy engine at 275 F at 4 K rpm and WOT and only 225 F at 2K rpm and WOT . In both cases the coolant temp was around 200 F. So logically, at no load (idle conditions) the oil sump temperature (even with the 200 F coolant temp will probably be below 200 F. So probably there will be much more condensation (taking place in the oil pan). But having said that-I would think that getting the vehicle up to temperature with a drive, say at least 30 minutes would probably cause little additional iron or wear. That's just speculation though [Smile]
 
Messages
64
Location
Texas
quote:
Originally posted by Al: Well more moisture will form bc the actual oil temps are much lower. There was an SAE paper (2000-01-1073) that gave oi sump temperatures on a V-8 Chevy engine at 275 F at 4 K rpm and WOT and only 225 F at 2K rpm and WOT . In both cases the coolant temp was around 200 F. So logically, at no load (idle conditions) the oil sump temperature (even with the 200 F coolant temp will probably be below 200 F. So probably there will be much more condensation (taking place in the oil pan).
Something's weird here... by "275 F at 4 K rpm and WOT and only 225 F at 2K rpm and WOT" does that mean that the engine was loaded down such that the RPM's remained at 2k or 4k at wide open throttle? If that's the case, that condition simulates extreme towing or cruising at very high speed and not so much regular driving. I'm not too familiar with coolant vs oil temps, but coolant temps obviously go way up during idling as evidenced by overheating issues and/or switching on of electric fans at a preset temp. Since the function of coolant is to remove heat from the engine, when the coolant is hot at idle due to lack of airflow and pumping volume, does that not also translate into a hot engine and thus hot oil? Matt
 
Messages
141
Location
San Francisco, CA USA
quote:
Originally posted by harper: Aside from the oil issue, excessive idling does not do wonders for the catlytic converter. Also the cat does not operate at normal conditions so emmission is higher especially at colder temperatures. Cat converters are designed for better performance at higher temps not colder temperatures.
yah, but it's not that big of a deal. what's more important, your motor or the cat? [Smile]
 

Al

Messages
19,256
Location
Elizabethtown, Pa
quote:
Originally posted by txmatt: [QUOTE]Originally posted by Al: [qb] ]Something's weird here... by "275 F at 4 K rpm and WOT and only 225 F at 2K rpm and WOT" does that mean that the engine was loaded down such that the RPM's remained at 2k or 4k at wide open throttle? If that's the case, that condition simulates extreme towing or cruising at very high speed and not so much regular driving. I'm not too familiar with coolant vs oil temps, but coolant temps obviously go way up during idling as evidenced by overheating issues and/or switching on of electric fans at a preset temp. Since the function of coolant is to remove heat from the engine, when the coolant is hot at idle due to lack of airflow and pumping volume, does that not also translate into a hot engine and thus hot oil? Matt
Well they used a dynomometer. So essentially WOT is full load at the given RPM. The Wide Open Throttle at 4K rpm would represent close to twice the HP output as 2K WOT. That would account for the extrem conditions. For this engine the 4K WOT is about maxed out HP wise [Smile] Does that make sense???
 
Messages
3,667
Location
St. Charles County, Missouri
This was a question directed to Click and Clack on Car Talk several months ago. Their take was that it was no harder on a modern fuel-injected engine than driving very very slowly. On the otherhand, since the rest of the car isn't being warmed up, why do it?
 
Messages
1,357
Location
California, USA
Owners manual comments about extended idling '92 BMW They specifically recommend against idling the engine to warm it up to operating temperature. '94 Ford truck If operating conditions include extensive idling, change the oil and filter every 200 operating hours, rather than using mileage intervals.
 
I guess I've been doing this all wrong then. I've been letting my truck warm up for 2 minutes before driving. I thought that would let all the internals warm up first.....I just dont like the idea of beating on a cold engine. What is standard? Should you let your engine warm up at all? I am very confused. FWIW I had no fuel in my first UOA while doing the 2 min. procedure.
 
Messages
988
Location
Melb, Aus
From my Nisssan S15 handbook (2002 200sx turbo model. last of series) "Warm-Up Allow the engine to idle for at least 30 seconds after starting. Drive at moderate speed for a short distance first, especially in cold weather."
 
Messages
11,284
Location
Spring HIll
quote:
Originally posted by Jimbo: '94 Ford truck If operating conditions include extensive idling, change the oil and filter every 200 operating hours, rather than using mileage intervals.
Jimbo, are you sure it doesn't read 20 hours in the owner's manual? 200 hours of operation, say at 60mph, is 12,000 miles! That seems like very long OCI when excessive idling is added in this mix.
 
Messages
8,711
Location
Nothern USA
quote:
Originally posted by csandste: This was a question directed to Click and Clack on Car Talk several months ago. Their take was that it was no harder on a modern fuel-injected engine than driving very very slowly. On the otherhand, since the rest of the car isn't being warmed up, why do it?
It galls me that my tax money goes to support them, but better them, than much of the rest on NPR
 

driven2services

Administrator
Messages
0
quote:
Originally posted by ToyotaNSaturn:
quote:
Originally posted by Jimbo: '94 Ford truck If operating conditions include extensive idling, change the oil and filter every 200 operating hours, rather than using mileage intervals.
Jimbo, are you sure it doesn't read 20 hours in the owner's manual? 200 hours of operation, say at 60mph, is 12,000 miles! That seems like very long OCI when excessive idling is added in this mix.

It probably means 200 hours of idling - as in alot less RPMs than 60mph.
 
Messages
1,420
Location
Balto.
quote:
Originally posted by jsharp: I don't buy this whole "idling is bad" thing. I think it's a problem from a bygone era. A modern fuel injected engine has little if any excess fuel to worry about, and as long as the engine has adequate oil flow to the top end and pressure to the bearings I don't see how it can hurt it to run with no load...
Whether it is a new fuel injected or an old carburetor & choke engine, the principle is the same. Cold engines run rich. The sooner they get up to operating temperature the better - for the engine, for your gas milage, for the air. [Patriot]
 
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