warm up time?

[cylynia]

hey guy... does anyone know how long should a 92 S13 warm up before can drive? i'm staying in the north,, so the average temperature here is about 10 - 20 F.

o.... and also which of the polarity of the battery should i take off before i can perform any electical work? another word,,, is it a positive earth or negative earth?

[Mayhem_J30]

especially in those kind of average temps you are right to be concerned. Just let it warm up until the idle drops down below 1000rpm. (don't know what the warm idle speed is on your car) but below a grand seems to be close to normal for nissans. takes my car about 5-10 minutes depending on just how cold it is outside.What kind of oil are you using?

I always just d/c both sides of the battery when I do work.

[erich]

Always disconnect the negative terminal first. If you disconnect the positive side first and touch the tool the the body you get a nice spark show, a burn on your hand, and a spot welded wrench.

erich

[red240ne]

you really shouldn't just let your car sit there and warm up. it's actually better for it to put a load on it while warming up. drive really slowly for a mile or so, not going over 2000rpms. it helps your bearings grease up to put a load on it. Also, it's normally warmed up about 1 minute or 2 after the needle has rested in the middle.

edit: post number 666!!

[Anand]

I've heard both sides... it is good to warm up.. and it is not good to warm up... what do all of you think abotu it... which is right!?!?!?!

[Mayhem_J30]

you really shouldn't just let your car sit there and warm up. it's actually better for it to put a load on it while warming up. drive really slowly for a mile or so, not going over 2000rpms. it helps your bearings grease up to put a load on it. Also, it's normally warmed up about 1 minute or 2 after the needle has rested in the middle.

edit: post number 666!!

i disagree. do you really want to put a load on those unlubricated bearings you're talking about? nissan programmed the ECU to run rich until coolant is warmed for a reason. you're car knows when it's warmed up and that's when the idle drops below 1000. when the coolant reaches a warm temp it's accepted that your oil temp has reached a warm temp as well since the two are usually battling for equilibrium.to help battle that wear that is caused prior to warm up and during cold starting a good synthetic oil (MObil1/Valvoline Synpower) should be used.driving under 2000 is definately better then bouncing the tach off of the redline to make it warm up. but there is a better way, the way the motor was designed

minimal load is desired until oil and coolant are at operating temperature

[Mayhem_J30]

thought this deserved a bump to clear up any false info being passed around out there in the internet world

[slw240sx]

also what about getting everything up to operating temp, i was actually sitting in my car today trying to decide if i should let it idle a minute longer or just drive it cold, i was considering that metal has expansion properties, what might be happening if im not letting that metal fully expand before i toruge the hell out of it, or what if its not fully lubed up an im tearing up the sides of the cylinder walls with dry pistons... i think it better to have a block heater, get everything warm and settled then turn it on, and let it idle a min or two to get it used to temp, then drive gentle for another 10-15mins to be sure, but who has that kinda time, i jump in turn it on wait till tha chain stops rattling so much and drive off, hoping that today is not the day it blows up on me 1

[not_a_porsche]

i disagree. do you really want to put a load on those unlubricated bearings you're talking about?

All of the bearings or anything important inside the engine will have sufficient oil within seconds of starting your car. Idling for more than 30 seconds will cause carbon buildup as the engine will be running rich at idle.

Letting it idle for 2 minutes every day say for a years worth of cold weather starting will result in 730 minutes (12+ hours) of rich idling. Does that sound like a good idea?

Reducing it to 30 seconds will result in 182 minutes (3 hours).

The rule of thumb I have always heard is 30 seconds is all you need, there is no benefit after that.

[PalmerWMD]

There may be no lubrication benefit after 30sec to 1 min BUT:The hard parts in the engiune are designed to operate when fully expanded in wamred up running.

Just one example:

Your rings will be loose when cold and permit extra blowby.that means more combusiotn gases enter the oil.

That means more oil dilution where the rings meet the cylinder walls (!!=wear), as well as a higher acid load on the oil due to the hi amount sulfur compounds in most gasoline stocks sold in the USA.But when idling the combustion pressure is low enough u wont have too much blowby even with cold parts.Once u put aload on engine u will see some blow by and u will see a lot more of it when the engine parts are still cold.

MayhemJ30 is 100% correct.

Fred...

[not_a_porsche]

There may be no lubrication benefit after 30sec to 1 min BUT:The hard parts in the engiune are designed to operate when fully expanded in wamred up running.

Your rings will be loose when cold and permit extra blowby.that means more combusiotn gases enter the oil.

Those are burned off when the engine is warmed up, as is the water that accumulates from condensation.

This is speculation, but I imagine the pistons/rings are up to operating temperature within 60 seconds. As long as you keep the rpm's low during the first couple of miles it isn't much different than sitting there idling at 1750rpm's waiting.

[PalmerWMD]

There are quite a few of combusiton products that dont burn of so easily.

Sulfur compounds (puts acid load on oil, once TBN additives in the oil are used up, those acids attack the bearings) and water come to mind.SOme who do a lot of short trips may have 5-10% water in their oil for the reasons mentioend above.

Also I believe it driving cold is different from rpm in warm-up, because there is very little load placed during warm-up unlike driving cuz of that pressures under the piston are higher and much more blowby occurs even in engines that are fairly tight otherwise.

Fred...

[SlowFiveOh]

more engine wear occurs at idle than at crusing speed. the force of the rods on the crankshaft journals is greater at slower speeds, but when everything is moving at a faster speed and the centrifical force takes over and actually eases the load on the bearings. as long as you let it run for about 20-30 seconds before you take off to let the engine build oil pressure youre ok. just dont flog it for the first couple miles.

think of it this way - you can hit something 1 time every second, or you can hit it 10 times a second. if you hit it 10 times a second it is more like a vibration instead of an actual impact.

as for the car running rich until it warms up and nissan putting that in the computer for a reason - well yeah, all manufacturers do that. the car needs more fuel when it is cold to run than when it is warm - 1. the converter needs to warm up faster to start working to reduce emissions 2. the extra fuel is needed for combustion since the cylinder temp. is low and does not aid in combustion at all at start up.

as far as the blowby, a motor in good health, that wont really be an issue, even for a tired motor it would be minimal and blowby at startup would be the least of your problems. unless you hear piston slap when the motor is cold i wouldnt worry about it at all. if your compression is good - your ring seal is OK.

[PalmerWMD]

yes the force on bearings is higher at lower rpms, but <idle> low rpms place very little load.Its different from engine lugging under load.

Fred...

[SlowFiveOh]

letting the engine idle when it is warm is even worse because the viscosity of the oil is thinner and clearances are greater once everything has expanded.

letting the engine idle may be easier on your fuel system but not the internal bearings. id rather spend 20 minutes replacing the fuel pump than rebuilding my motor.

[C-Kwik]

more engine wear occurs at idle than at crusing speed. the force of the rods on the crankshaft journals is greater at slower speeds, but when everything is moving at a faster speed and the centrifical force takes over and actually eases the load on the bearings. as long as you let it run for about 20-30 seconds before you take off to let the engine build oil pressure youre ok. just dont flog it for the first couple miles.

think of it this way - you can hit something 1 time every second, or you can hit it 10 times a second. if you hit it 10 times a second it is more like a vibration instead of an actual impact.

as for the car running rich until it warms up and nissan putting that in the computer for a reason - well yeah, all manufacturers do that. the car needs more fuel when it is cold to run than when it is warm - 1. the converter needs to warm up faster to start working to reduce emissions 2. the extra fuel is needed for combustion since the cylinder temp. is low and does not aid in combustion at all at start up.

as far as the blowby, a motor in good health, that wont really be an issue, even for a tired motor it would be minimal and blowby at startup would be the least of your problems. unless you hear piston slap when the motor is cold i wouldnt worry about it at all. if your compression is good - your ring seal is OK.

The rod bearings will typically see it's highest load from the inertial load of the piston and rod. And the inertial load is higher when engine speeds are higher. 10 impacts per second is 10 impacts per second. The inertial load will determine the severity of the impact. With say 10 impacts per second vs one impact per second, then I would assume the engine is spinning 10 times faster and would have 10 times the inertial load.

As far as warming up, you have to also consider oil viscosity. Is the cold oil actually lubricating the parts well? Under higher inertial loads, do you want to trust that the thicker oil is doing a great job? Consider the fact that the motor was engineered to run in a certain temperature range. And consider that the original post asked about in ambient temperatures of 10-20 degrees F. That's below the freezing point of water. I would let it idle. If not to save the engine, to get the heater up to speed so you don't freeze to death inside the car.

[SlowFiveOh]

The rod bearings will typically see it's highest load from the inertial load of the piston and rod. And the inertial load is higher when engine speeds are higher. 10 impacts per second is 10 impacts per second. The inertial load will determine the severity of the impact. With say 10 impacts per second vs one impact per second, then I would assume the engine is spinning 10 times faster and would have 10 times the inertial load.

As far as warming up, you have to also consider oil viscosity. Is the cold oil actually lubricating the parts well? Under higher inertial loads, do you want to trust that the thicker oil is doing a great job? Consider the fact that the motor was engineered to run in a certain temperature range. And consider that the original post asked about in ambient temperatures of 10-20 degrees F. That's below the freezing point of water. I would let it idle. If not to save the engine, to get the heater up to speed so you don't freeze to death inside the car.

wrong, but eh, 3 years of tech school and ASE certification, what do I know :rolleyes

[chrispy]

i usually just warm up my car just because there is ice on my windshield

[C-Kwik]

wrong, but eh, 3 years of tech school and ASE certification, what do I know :rolleyes

So wouyld you like to elaborate, or should we consider you all knowing because you went to tech school for 3 years?

"10 years of experience is not the same as the same year of experience 10 times."

[SlowFiveOh]

never said i was all knowing, but goign through 3 years of auto tech (not high school vocational) ive learned a lot, and thats just the way it is. you can go on thinking that there is less stress on the bearings at idle for all i care.

im just sharing what i know, im not going to fight about it or anything.

ill go through my text books from school and see if i can find anything on it and i will type it word for word if i can find anything in them.

[KFL]

never said i was all knowing, but goign through 3 years of auto tech (not high school vocational) ive learned a lot, and thats just the way it is. you can go on thinking that there is less stress on the bearings at idle for all i care.

im just sharing what i know, im not going to fight about it or anything.

ill go through my text books from school and see if i can find anything on it and i will type it word for word if i can find anything in them.

I have to agree that idling for a long period of time is bad just drive slowly until normal operating temp is reached.My auto instructors most Master Techs/ASE Certified yadda yadda 10-30+years in the field have said the same thing.

[SlowFiveOh]

I have to agree that idling for a long period of time is bad just drive slowly until normal operating temp is reached.My auto instructors most Master Techs/ASE Certified yadda yadda 10-30+years in the field have said the same thing.

thank you

[red240ne]

thank you

Yes, i agree, that's why i started this argument. My Autotech teacher is god when it comes to cars, so I always take every thing he says very seriously.

[groundhogday1976]

The owner's manual says 30 seconds of warmup for a reason. I don't know the reasons behind it or any of the physics stuff you guys are arguing about, but if the factory says 30 seconds is sufficient, they did so for a reason. I let my car warm up longer than that right now, but that's just because it's too damn cold. You can bet when it gets warm enough I'll be idling 30 seconds, driving like granny for a couple of miles, and then drive normally.

[turboweege]

its actually pretty lubed up after 30 seconds and from some books ive read on extending the life of a car its better to warm for 30 seconds then keep rpms under 3k until the engine is at op temps. this also lets the transmission warm up with the engine rather than taking off in a warm engine with an unlubed cold transmission. just a thought. luigi

[Mayhem_J30]

its actually pretty lubed up after 30 seconds and from some books ive read on extending the life of a car its better to warm for 30 seconds then keep rpms under 3k until the engine is at op temps. this also lets the transmission warm up with the engine rather than taking off in a warm engine with an unlubed cold transmission. just a thought. luigi

even though i do the full several minute warm up i still do the granny drivin for the first mile or two. mainly the ATF doesn't seem to warm up like the motor fluids do and creates abrupt shifting. there doesn't seem to me to be a work around for this. maybe m/t's are different but the a/t are cold unless they get used. any ideas?

good posts btw guys!

cylynia,did this answer your concerns or just create more..LOL. obviously this is still a debate no ones agrees on.

[turboweege]

well, there are transmission and block heaters.....

[C-Kwik]

I have to agree that idling for a long period of time is bad just drive slowly until normal operating temp is reached.My auto instructors most Master Techs/ASE Certified yadda yadda 10-30+years in the field have said the same thing.

Ok, but can anyone explain exactly why. I'm not the type of person who accepts these types of answers. It's not personal, but I won't swear by anyone else's knowledge unless they can explain to some reasonable extent why it is true.

I've met many mechanics who are ASE certified, and know how to fix a problem, but have not technical understanding of why things work the way they do. ASE certification is nothing more than a piece of paper. One can learn as much or more as any ASE certified person on their own. Making an argument and backing it up with a piece of paper that says you passed a test says nothing. Making an argument and showing why the argument is true has much more credibility. I'm just waiting for the credibility...

[red240ne]

Well yea, he said he had textbooks, so why not bring those into the argument? That might solve a few questions.

[sil80drifter]

Those are burned off when the engine is warmed up, as is the water that accumulates from condensation.

What are burned off? The gas in the oil? How? Since when? I don't have piston oil squirters on my SOHC. But DOHC doesn't really burn oil either...nor does it burn the gas in the oil.

This is speculation, but I imagine the pistons/rings are up to operating temperature within 60 seconds. As long as you keep the rpm's low during the first couple of miles it isn't much different than sitting there idling at 1750rpm's waiting.

What car are you in when you idle at 1750 RPM? Not a 240SX I'm sure. The highest our cold idle goes is about 1250 (if not 1200), and usually drops to 1000 and then back to normal idling of 750 + - 50RPM.

Warming up is not just about lubrication. It's also about metal expansion. And when you have a cast iron block and an aluminum head, they expand at different rates, the head faster than the block. So when you drive around with a cold car, you are damaging either, if not both. Not much, but enough to make ur engine need a rebuild around 150k. Warm up, at least 5 mins in the winter. Bestly, as logn as it take for your temp. arrow to reach the middle. There is a statistic that 70% of engine damage occurs because most people fail to warm their cars up. Serious engine damage, not a broken hose or leaky exhaust.

sil80