"Warming up an engine"
12-15-2003, 05:28 PM
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"Warming up an engine"
Ok guys, dispell this myth for me. Are you actually prolonging your engine life if you allow it to run for a feww minutes before you drive? Or are you just wasting fuel? I warm mine up but others tell me its a waste of gas and time. Whos right in your opinion, me for warming it up, or the others for not?
12-15-2003, 05:43 PM
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That is a very good question. 
They way I understand it, modern engines do not need to be preheated like older engines. Now don't get me wrong, you still would never want to start a cold engine and immediately run it really hard.
I think you are actually burning extra fuel and causing additional wear on the engine if you let it idle for more than a minute or so.
I think I remember a segment on Motor Week (PBS car show) a while back that addressed just this topic.
-S
They way I understand it, modern engines do not need to be preheated like older engines. Now don't get me wrong, you still would never want to start a cold engine and immediately run it really hard.
I think you are actually burning extra fuel and causing additional wear on the engine if you let it idle for more than a minute or so.
I think I remember a segment on Motor Week (PBS car show) a while back that addressed just this topic.
-S
12-15-2003, 05:46 PM
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As far as I know, it is best to let the rpms drop to idle speed (or near idle speed) and then it's okay to drive. Does that make sense? what do you guys think? I'm not sure if it applies to all motors, but i Know that the 3vze responds particulary well to this kind of boot-up 
12-15-2003, 07:09 PM
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I think I heard on Click and Clack to wait til your oil pressure gauge stops rising. and if you dont have a gauge wait about 10 seconds or so. By that time the oil should be sent to every nook and cranny in that engine.
12-15-2003, 08:32 PM
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From what I understand, it's worse for your engine to let it idle too long, warming it up or otherwise. You only need about 10 seconds (as per above) for the oil to be lubricating everything and 1 to 2 minutes is enough in extremely cold weather. Extensive warm-ups waste gas and lead to unnecessary carbon buildup.
12-15-2003, 08:38 PM
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yah, but if the motor is revving at 1500 rpms, it can't possibly be good to drive it at that time. why does it rev so high then when its cold?
isn't idling it when its COLD the same thing as driving really slow except there is no stress on the engine components?
I mean, i understand idling the motor when it is idling at idle speed, but when at fast idle, you might as well be driving except it gives the motor a chance to warm up without putting stress on it if you wait to drive it until it hits idle speed.
I personally believe, and it only makes sense, that it is safe to drive the motor normally when the idle speed comes down to what its supposed to be set to.
I mean perhaps you could baby it until it gets warm, but I don't have the patience for that, I like to hop in and go right away without worrying if the motor is ready to take a beating - the best way to do that it seems, is listen to the motor; watch it. when it is ready, it will lower rpms signifying that it's ready.
any counter arguments?
( i am all against idling when rpms are at idle speed, but if above that, that's what i'm arguing for).
isn't idling it when its COLD the same thing as driving really slow except there is no stress on the engine components?
I mean, i understand idling the motor when it is idling at idle speed, but when at fast idle, you might as well be driving except it gives the motor a chance to warm up without putting stress on it if you wait to drive it until it hits idle speed.
I personally believe, and it only makes sense, that it is safe to drive the motor normally when the idle speed comes down to what its supposed to be set to.
I mean perhaps you could baby it until it gets warm, but I don't have the patience for that, I like to hop in and go right away without worrying if the motor is ready to take a beating - the best way to do that it seems, is listen to the motor; watch it. when it is ready, it will lower rpms signifying that it's ready.
any counter arguments?
( i am all against idling when rpms are at idle speed, but if above that, that's what i'm arguing for).
Last edited by ByThaBay; 12-15-2003 at 08:42 PM.
12-15-2003, 08:49 PM
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I would never let my ol Lexus es300 warm up in the NC Mountains. By the time I walked outside to crank it up i was so friggin cold that I figured it would warm up faster if I drove it. This car would seem to be faster and more peppy before it warmed up (cold air theory)????? does that make sense, should it accelerate faster cold. My 1969 Mustang has an auto choke that is activated everytime it was started. It would register 1000 + until I reved it up, disengaging the auto choke thus dropping the rpms down.
Last edited by Hyperlite; 12-15-2003 at 08:53 PM.
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12-15-2003, 11:22 PM
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Sitting at idle doesn't push oil to the top end of the engine efficiently. A part of what produces the high idle in modern engines is the dashpot of the emissions control. It remains further open to allow the excess exhaust gasses back through the engine to be burned further. It's a nice idea, but exhaust doesn't really burn a second time all that well. As the engine warms up, the dashpot closes down as the fuel starts to burn more efficiently. By letting it sit and warm up you're not only stressing your engine by not lubing it efficiently but also pushing more exhaust into our already stressed atmostphere.
Where winter temperatures average 20 degrees or more, turn the key and drive off non-lunatic like. The easy driving for a mile or so both forces the oil to circulate, and thereby warm up faster, as well as avoid undue stress you'd incur on the internals by just racing off on a cold engine and pushing a blast of cold-thickened oil through the block and top end. Friction folks, even oil is subject to its effects, and by slowly circulating that oil throughout the engine sooner, you're going to warm it up faster. In being the quickest way your engine warms at those temperatures, it's also the kindest your gasoline engine will be to the environment.
Where winter temperatures are prone to run below 20 degrees for extended periods, invest in a freeze plug block heater or a glue-on oil pan heater and plug it in for an hour to three before you leave. I plug mine in when I get home and just leave it overnight. Costs about as much in electricity as a low watt light bulb and gets warm oil circulating through your engine from the minute your turn the key. The idle then kicks down about as fast as it does at 50 degrees, and your emissions go to their total warm up minimum by the time you leave the driveway. It also gets warm air blowing in the cab in no time.
Where winter temperatures average 20 degrees or more, turn the key and drive off non-lunatic like. The easy driving for a mile or so both forces the oil to circulate, and thereby warm up faster, as well as avoid undue stress you'd incur on the internals by just racing off on a cold engine and pushing a blast of cold-thickened oil through the block and top end. Friction folks, even oil is subject to its effects, and by slowly circulating that oil throughout the engine sooner, you're going to warm it up faster. In being the quickest way your engine warms at those temperatures, it's also the kindest your gasoline engine will be to the environment.
Where winter temperatures are prone to run below 20 degrees for extended periods, invest in a freeze plug block heater or a glue-on oil pan heater and plug it in for an hour to three before you leave. I plug mine in when I get home and just leave it overnight. Costs about as much in electricity as a low watt light bulb and gets warm oil circulating through your engine from the minute your turn the key. The idle then kicks down about as fast as it does at 50 degrees, and your emissions go to their total warm up minimum by the time you leave the driveway. It also gets warm air blowing in the cab in no time.
12-15-2003, 11:46 PM
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Hey that is pretty interesting stuff.
I noticed that if I just drive off, the engine immediately drops down to a lower idle speed when I put it in "D". I always thought it was the load of the tranny making the idle go down but maybe it's that whole emissions thing.
I don't have the patience to wait for the engine to warm up, maybe it's a good thing after all.
I noticed that if I just drive off, the engine immediately drops down to a lower idle speed when I put it in "D". I always thought it was the load of the tranny making the idle go down but maybe it's that whole emissions thing.
I don't have the patience to wait for the engine to warm up, maybe it's a good thing after all.
12-16-2003, 09:38 AM
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Exhaust gas recirculation (EGR) has nothing to do with cold start high idle.
The high idle speed at cold start has to do with an engines unwillingness to run when cold at the hot idle speed. It just stalls. As an engine warms up, it is better able to idle at lower rpms, and the idle is lowered according. This problem was much worse with carbureted engines that would suffer from gasoline dropout.
Exhaust gas recirculation does not take place when cold, or at idle. It also has nothing to do with reburning the fuel. It has to do with diluting the combustion temperature in the cylinder due to slowing down the burn rate. It reduces NOx emissions.
There is not any danger of doing damage to the engine from a "blast of cold oil". Quite the contrary, there is a very real danger to an engine from lack of lubrication because cold thick oil doesn't flow well. This is the original reason for multi-weight oils, and the reason for not using an excessively thick oil in winter months.
An engine is safe to operate in a reasonable manner after a few seconds of operation, giving it a chance to stabilize. The older the engine, the more out of tune it is, the longer this time for stabilization might be.
This has nothing to do with the rest of the vehicle. A manual transmission that cannot be shifted until things are warmer is a good reason to let that particular vehicle warm up longer. Same with refrosting a windshield.
The high idle speed at cold start has to do with an engines unwillingness to run when cold at the hot idle speed. It just stalls. As an engine warms up, it is better able to idle at lower rpms, and the idle is lowered according. This problem was much worse with carbureted engines that would suffer from gasoline dropout.
Exhaust gas recirculation does not take place when cold, or at idle. It also has nothing to do with reburning the fuel. It has to do with diluting the combustion temperature in the cylinder due to slowing down the burn rate. It reduces NOx emissions.
There is not any danger of doing damage to the engine from a "blast of cold oil". Quite the contrary, there is a very real danger to an engine from lack of lubrication because cold thick oil doesn't flow well. This is the original reason for multi-weight oils, and the reason for not using an excessively thick oil in winter months.
An engine is safe to operate in a reasonable manner after a few seconds of operation, giving it a chance to stabilize. The older the engine, the more out of tune it is, the longer this time for stabilization might be.
This has nothing to do with the rest of the vehicle. A manual transmission that cannot be shifted until things are warmer is a good reason to let that particular vehicle warm up longer. Same with refrosting a windshield.
12-16-2003, 09:47 AM
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wow, you hit the nail right one the head. That's exactly how I feel. Indeed, my shifts are a lot smoother if i let the truck warm up a few mins before driving off.
12-16-2003, 10:08 AM
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Hm. Better science; thanks.
Would you agree though with how I intended the cold blast of oil bit - that warm oil flows and lubes better? I didn't really imply "damage" would immediately follow being raced off the line cold, but rather that in the long run it reduces wear on the engine to drive more moderately ("a mile or so") til the oil can get to a decent temperature to flow more freely.
Would you agree though with how I intended the cold blast of oil bit - that warm oil flows and lubes better? I didn't really imply "damage" would immediately follow being raced off the line cold, but rather that in the long run it reduces wear on the engine to drive more moderately ("a mile or so") til the oil can get to a decent temperature to flow more freely.
12-16-2003, 11:48 AM
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Originally posted by WileEToyote
I got mine at the stealership. The part is pretty cheap; it's the install that gouges ya.
I got mine at the stealership. The part is pretty cheap; it's the install that gouges ya.
12-16-2003, 12:23 PM
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Originally posted by WileEToyote...it's the install that gouges ya.
Really? How hard was it? Do you have pics & a writeup?
You need to remove one of the freeze plugs from the block. All the info I could find led me to believe this meant drilling and tapping it, so I left it to someone who could be held more accountable if it got screwed up.
The "Alaska Pad" glue on heaters just take a goodly sized gob of adhesive slathered on the oil pan, then feed the plug out through the grill. You can pick those up at any parts store...at least you can in the way north here.
12-16-2003, 02:46 PM
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Sounds like something better left to the pros. As for the oil pan heater, I'll look around here or order one from JC Whitney.
12-16-2003, 03:15 PM
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i got this off some auto insurance site...
Vehicle Warm Up
When starting a vehicle in cold weather allow the engine to idle for a few seconds before driving off to insure proper oil flow and lubrication. Do not allow engine to idle for a prolonged period after start up in cold weather. This practice wastes fuel and does not warm up drive train components. After starts, drive easily for several miles to ensure proper vehicle warm up.
Vehicle Warm Up
When starting a vehicle in cold weather allow the engine to idle for a few seconds before driving off to insure proper oil flow and lubrication. Do not allow engine to idle for a prolonged period after start up in cold weather. This practice wastes fuel and does not warm up drive train components. After starts, drive easily for several miles to ensure proper vehicle warm up.
