Better to idle or better to drive on a cold engine

[dripley]

I idled mine like a gasser when I first bought it until i figued out it did not do alot of good. Driving it was the only way to warm it up. I first had to do alot of learning when I bought it. Did not know about all the forums.

[AABEAR]

There was a post about this and I wanted to really dive into it and see everyones opinions and stuff on the issue. So it is 0F out and you go out to your truck and fire it up. From the way most sound at 0F, you will surely wait 30 seconds before doing anything else. But after that, then what is best to do? Here is my theory. When you start the engine, the first thing to get warm is the piston. It is aluminum and in direct contact with the explosion above it. The next thing would be the exhaust valve though it's composition would resist it. Then I think the rest would be relatively uniform. The thing I see here is that the piston would be hot and therefore expand. The cylinder walls would have 0F coolant rushing past them and being steel they would not be heating up much at all. Therefore, I think this accelerates wear on the rings until the cylinder walls reach operating temperature. While idling, the engine is really not making much heat. I can idle mine for 10 minutes and be lucky to hit 80F from 0F. If I waited for 100F before I left, it would be idling a longgg time. Over the course of this duration, how much wear am I causing? On the other hand, what if I started driving after that 30 seconds, not hard, just putter out of the driveway and slowly get up to 55mph (I live on a highway). This would make it heat up faster, but would the shorter duration make up for the cylinder strokes? After all, it would be turning 1600RPM or something instead of idle speed.. Seems doing this would be more likely to polish the cylinder walls, ridding them of the crosshatch. My EGT's are also very high on a cold engine at 55mph, scratching 600F. A warm engine is barely over 400F. So it is producing more heat but is it worth the wear of whatever it is wearing that is making the engine so hard to turn which makes me give it more fuel and the EGT's show the load. I'll get some interesting calculations up in a bit. I believe driving is better on it, but I am not sure, that's why I am posting this...

Why not plug it in ?? You can put it on a timer 3 Hr will make it warm up some cheeper than fuel!! You might ask Commins what they think is best.

[cumminapart]

I got a timer late into last winter and have yet to actually use it As Mopar pointed out its been so warm this winter everywhere I think We Saw mid 50's last week for a day and supposed to be 50 again Wednesday Maybe we should all stop idling before global warming completely takes a hold Haha.... Completely kidding there --- I am here: http://maps.google.com/maps?ll=42.674964,-84.075705

[Mopar1973Man]

I got a timer late into last winter and have yet to actually use it

As Mopar pointed out its been so warm this winter everywhere I think

We Saw mid 50's last week for a day and supposed to be 50 again Wednesday

Maybe we should all stop idling before global warming completely takes a hold

Haha.... Completely kidding there

---

I am here: http://maps.google.com/maps?ll=42.674964,-84.075705

OMG!

Maybe USFS (US forest Service) could quit lighting control burns out here and filling the sky with orange haze from all the smoke.

I believe the planet is self healing in a lot of respects. Like everything has a balance and will renew everything to that balance. But flood or offset that balance it might take some time for it to over come the in-balance. (like a forest fire).

Now with all the horror stories of health impacts its the same way. I'm out in shops and dynos where the shop is flood with diesel soot. Yeah I know its not exactly healthy but geez... Just like working in a forest fire for over 25-30 day in thick smoke. I didn't drop dead nor did any of the other fire fighters.

Carbon foot print... Get real... Once again get after the US Forest circus...

Nice tree torch from Poe Cabin, Idaho Fire (US forest Circus set the fire!)

I better get off my soap box...

[Pondsy]

I generally prefer to start it, let it run for 30 seconds...turn on the high idler...run in and get my stuff together (about 1-2 minutes) and that's it. I get in, turn off the high idle feature and go...drive slow till I get to the highway and I have heat within a mile. Haven't been able to do that lately though...throttle was getting no response...truck just wouldn't move. Let it warm on high idle for about 10 minutes and it was fine...but then it wasn't...began having issue with the throttle (what I'll call dead peddle) and the research about VP failures was on. Hoping I can go back to my original warm ups once it's replaced...saves on fuel and the neighbors REALLY appreciate it on those 4 am starts!

[ISX]

I got a ton of information on this now. I'm still getting some information so give me another day.

[ISX]

After much research, I have the results. The winner is, starting for 30 seconds and driving off. The basic answer is that load = wear and tear. When you get in and start it and go (after 30 seconds or so, since this was a 0F startup..), it might be up around 550-600F at 55mph but that isn't exactly an indicator of load. If you have a scan gauge on a 24V, you can see percentage of load. I'm guessing the load of a cold engine at 55mph is maybe 5-10%. Though there is a load which is some wear, you are on your way to the destination as well as warming up the engine, so it is the best of both worlds. A cold engine having tighter tolerances wears more, so warming it up while driving saves you on fuel and gives the engine a slight load to get it warming up faster. Idling is the second best. It isn't warming up because there isn't a load, but there isn't the wear of a load either. It is just kinda bumping along wasting time, but gets hot eventually, after a half hour or something, it really generates no heat but the only real wear is from the tight tolerances of the engine. It is a waste of time to let it just sit there and idle. It will warm up eventually but yeah, from a wear and efficiency of your time and fuel aspect, it isn't #1..Idling with the exhaust brake is 3rd worst. It puts a load on the engine causing wear, but does so twice, during the power stroke since it has to fuel harder because of the resistance of the E brake on other cylinders, and the exhaust stroke because of the resistance of the exhaust. I'll explain this later. It does heat the engine up faster than idling, but you still are sitting there, wasting time and money, going nowhere. High idle exhaust brake is worse yet, heats up slightly faster but with higher load factors meaning more wear. 4th worst is 3 cylinder high idle. From Mike's EGT and Load tables, it shows an incredible load on the engine. However this is only on 3 cylinders, wearing them out more than the other 3, potentially causing differences in compression between those 3 and the other 3 cylinders. It is the same load as just driving off, maybe more even. The difference is that you are wearing 3 cylinders more than the other 3, and you still have to drive to your destination, causing even more wear. Last but not least, 3 cyl idle and exhaust brake. You have a LOT more load than driving off and the exhaust brake loads the cylinders twice. This causes even more uneven wear between the powered 3 and the dead 3. The 3 dead cylinders are also staying colder longer. So, WHY you might ask. The answer is side loading. In a perfect world, the piston would have a connecting rod that was perfectly straight and delivered power as such. Being on earth, we have a connecting rod that follows the radius of the crankshaft. This means that the only "perfect" times are when the piston is at absolute TDC or BDC. At all other times, the pistons are at an angle to a connecting rod. If you ever hold a connecting rod with the piston above it, it will fall to one side or the other depending on the angle. The same thing happens in the engine. The combustion event causes the piston to fall to one side or another, but the rings resist. This causes one side to wear more than the other sides. Pistons are made ovular on new engines to counter this. The bore is a perfect circle but the piston has to break in and since wear is going to happen during this period, they make them ovular so that the side load of the piston will wear them back down to a perfect circle. Any load on the engine adds to the side load or "wear" of the piston rings. This is why more load = more wear. An exhaust brake adds a load to the exhaust stroke which is the opposite angle of the power stroke so it would wear the other side of the piston. Now, this isn't really something to worry about. Caj has a load on his engine the entire time and apparently it didn't wear out enough to stop driving it after a million miles lol. Though he is also in a warm climate so who knows. I have no information on how much wear each thing would cause, but that is the order it would be in for this thread. It was based on wear and just common sense, as in if your not warming it up, then whats the point. I'm all ears to any and all opinions, facts, counterattacks on me lol. I researched this a lot but that doesn't mean everything is perfectly accurate, but it is to my knowledge so far.

[Mopar1973Man]

Hmmm. Now my shot at you ISX... Ok so how about CajFlynn idling for several hours sleeping in the cab with the heater going no exhaust brake?But I got to disagree with the wear factor of high idle function and exhaust brake. The coolant temperature is rising at a fairly rapid pace so within about 3-5 minutes its already like 100-120*F in coolant temp so the oil temperature has to be following close behind as well so the wear factor can't be worse with exhaust brake and high idle. The fact the metal are warming up very fast and the tight tolerances are loosening up rapidily compared to just idling at 250*F at 0*F outside morning... So without the high idle and exhaust brake you could virtually hang at below 100*F of coolant temp for more than 20-30 minutes.But as for MPG and efficency its best to start and get rolling. Just using high idle function and exhaust brake can flow some serious fuel over a short period of time I've measured upwards of 6-10 GPH just using the high idle function with exhaust brake so this fuel is now lost and there is no miles to account for it. So to agree with ISX from the MPG efficency stand point its best to start, idle for about 30-60 seconds and get rolling. But as for the wear stand point I'm going to have to disagree... at least from my point of view... (Discussion turn over ot the next person that post)

[cumminapart]

"The bore is a perfect circle but the piston has to break in and since wear is going to happen during this period, they make them ovular so that the side load of the piston will wear them back down to a perfect circle."In my understanding this isn't necessarily true."Cam ground" pistons are somewhat oval with the dimensions parallel to the pin being somewhat longer than the distance across the pin. This is of course when measuring at roomTemp.The reason being is that the added mass and different material of the pin means less expansion. By using cam ground pistons once operating temps are reached the piston will be round.Another thing is tapered cylinders. The top of the cylinder is a smaller diameter. This makes sense because the top is going to see more heat therefore expanding more. Tapering the cylinder allows for it to be straight at operational temperatures.This is a bigger issue with air cooled engines however because they see hotter temps and typically less evenCooling.Sent from my iPhone using Tapatalk

[anoldbiker]

Have you also consider that during the winter months, fuel has lower energy per the same quantity then in it has in the summer months, and this can be a factor in initial heat gains from start up ?

[Mopar1973Man]

Have you also consider that during the winter months, fuel has lower energy per the same quantity then in it has in the summer months, and this can be a factor in initial heat gains from start up ?

Like the fact the cetane is a huge facotr in that...

Dark green - summer fuels

Light green - winter fuels

This why I keep telling people don't use a anti-gel or cetane boost unless you really need too. Because in both cases all it does is reduced the power output (BTU's) and reduce MPG's

[flagmanruss]

I seldom get to zero here... thankfully. I am a fan of plugging it in if I know I'm going to use it on an especially cold morning... but the temp does not register on the guage on start up so still a pretty cold engine. I start her up... watch the oil pressure until it stops climbing. I'll put it in Reverse & back out into the driveway. Put it in park, fasten the seatbelt (easier to turn around to see without belt). Start off, drive easy... it's 5 minutes of local roads to the state highway, frequently I'll begin to show engine temp about then... I'm not stressing anything, just loafing along but at least I'm getting some miles for the fuel. I don't normally tow in cold weather but I have (more with the C30 454) in which case I warmed up until the temperature guage started to move before moving.

[dripley]

A good while back I ran Kleen diesel Cetane booster and what ever else it claim(+mpg was one). I never saw any differance in any thing good ar bad. I think i ran it for maybe 6 months or less and quit. I did not seem to deliver anything. I also did not know much of anything at the time about how this diesel works. I do now thanks to this site.

[cumminapart]

but the temp does not register on the guage on start up so still a pretty cold engine. .

Which gauge?I'm assuming you mean the water temp gauge The temp of the oil is what should be higher I believe Someone correct me if I'm wrong because I'm not completely sure.. Does it actually heat the block? Even if it does it'll only heat the coolant inside the block Sent from my iPhone using Tapatalk

[ISX]

I gotta research this stuff more. I am researching at lunch time and the few hours I have after work lately, worked like 18 days straight now, not that it really matters because I know a lot of you work for much longer durations, but I like my time off so I can learn more stuff lol. I have yet to see actual proof of anything, only theories. I reiterated all the theories into one right up. Mike doesn't have actual proof either. It just kills me that I don't have equipment to test everything I want. My dream in life would be to have each version of cummins (VE, P7100, VP44, CR) all in a row acting as generators. They would all have the same ECM and/or PCM as was in our trucks, this way everything is equal. I know a CR generator would probably be tuned different. Then I would have a load that I could vary, be it a grid of heating coils or something that would supply the power grid to pay me back for testing (I like that idea). Then I could really see the effects. A lot of the trouble with trucks is setting up something. The engine is in a truck for one, I have made my truck as easy as possible to work with but it still has it's limits. The engine also doesn't have a reputable load. A generator with a known resistance heating coil would always be the same load, so all engines would have an equal load and testing for comparisons would be very accurate. I could also test different products and whatnot with an engine dyno. It would be a full blown engine testing setup.. But until then, I can only assume.

[dripley]

Which gauge?I'm assuming you mean the water temp gauge The temp of the oil is what should be higher I believe Someone correct me if I'm wrong because I'm not completely sure.. Does it actually heat the block? Even if it does it'll only heat the coolant inside the block Sent from my iPhone using Tapatalk

the heater is in the water in the block. it will warm the block and I would think anything that is in it, water and the oil. The oil in the pan would be a differant story. I would think it would still be cold.

[ccrider]

According to my pulse monitor from quadzilla the engine load with high idle (not 3 cylinder) puts less load on. Who knows if their load guage acctually works right Just idling when I first start up it is at 22% load with grid heater cycling and all that, with high idle it seems to only idle at around 10% load. Taking off after a minute of idling or so trucks at about 25-30% load. Dosent seem right to me but i dont really know. Just started reading this topic, very interesting. I live in northern michigan and have just started letting it warm up for a minute and then going to where I have to go nice and easy

[Baconbitsforu]

strange. with my edge the load is 0-2 at idle and 11 in gear with brake on