I don't even think about pluggin mine in until about -20C (that's -4F). When I start mine at lets say -15C (+5F), I let the grid heater run however it wants to then start it. it changes depending on the temp, but at that temp the grid heater will run about 2 minutes before it's ready to start. Then I let it run about 30 seconds then I drive it away. I'm pretty much idle out of the neighborhood (about 1/2 mile) then I gradually increase to 100km as I am drving out of town for the next mile getting onto the highway. Mostly what I watch is the boost gauge, I try to keep the boost down to about 10 to not work it too hard. I takes about 10 miles of driving it before the temp gauge starts to move and I start to get reall heat from the heater. The whole time the engine runs smooth. I knocks a bit harder for the first 15 secons or so but it smooths out right away. Most long time diesel owners around her tell me that's nothing. Pre duramax cheves sound like they are going to fly apart when they are cold (the noise is so bad you can't be near them) and it doesn't hurt them much.

I have tried a couple of things, if it's not too cold (like -15C) and I run it for 10-15 minutes first, it does not warm up but it does shorten the time it takes to warm up when driving. I can get heat within a mile if I do this.

However, the fact that idling the engine even when fully warm under no load in these temp conditions (like -15c) will drop the temp gauge back down on the pin in just a few minutes (like the time it takes to run through the drive through) makes me think idling is not good at all. Fuel doesn't burn properly when the engine is cooler and you get carbon packing around the rings; which if allow to build up (from doing this daily) and then later harden under temperature makes for nice almost diamond hard scratchers for messing up your cylinder walls.

My dad has run heavy trucks for 20+ years. Some models would drop carbon suit all over the place when warming up (real obvious example of not burning your fuel right). And he was always told by CAT mechanices to idle up however much you had to to keep the engine temp up, that meant up to 2000RPM if necessary (300 RPM from red on a 13l cat) if you had to. Anthing but normal operating temps was BAD BAD BAD. Now bigger trucks can idle to warm up because then can run up to 1500RPM or more but most of us don't do that. Plus a bigger truck runs compressors, massive oil pumps and some even turn the engine fan on to add some load.

I would not want to start mine below -20C without being plugged in (I think that would be too hard on it), but the manuel does say with the grid heater one should be able to start it down to -40C. You can tell when you start it if it's too cold and should have been plugged in, it runs and sputters like a pig, not that the miss firing is necessarily bad for it in itself, but that is builiding a lot of carbon then and that's the thing that is not good.

Long story short: you got to drive it to get it to warm up and idling = bad. Or at least REV it up - a lot.

I do use synthetic oil in the winter. Synthetic does poor like 10x better in the cold then mineral.

Oh ya, and the guy that said he when it's cold he runs out and starts it in his undies... if it was warm enough to do that here I wouldnt even be thinking about it. But thats all a matter of perspective from what we are used to and where we live. I think it's funny to hear though being from Alberta.

 

Mark,

My thought on the grid heater is just an opinion. But as far as bearings go, the speed is not relevant to the oil wedge. Many big bearings turn slower than the cranking speed of the Cummins. And when the engine fires the first few times the bearing load goes way up.

I don't want to start a war here but the oil pressure is not what keeps the bearings from contacting the journals. They only must have oil present to form the oil wedge. The pressure delivers the oil, rinses the contaminates out and cools the bearings. Also the excess oil flying out of the bearings is what lubes the cylinder walls. It seems more important to the cylinders to get the pressure up right away. Especially since the area above the piston is essentially open to the atmosphere where it can collect moisture and condense out combustion products. Considering the top of the cylinder, where only the top ring rides, and how that area gets exposed to the full power stroke fire, and how little oil is actually delivered there, I'm just amazed that engines don't wear faster than they do. I've never actually worn one out. The Cummins is the last one I should be able to wear out with it's heavy construction.

Wetspirit

 

Wetspirit,

Speed is relavant. I'm not as concerned about the oil pump building pressure as I am about the bearing being able to 'grab' the oil so it can build the wedge. The ability of the journal to grab the oil is a function of journal area, diameter, load, and oil viscosity & pourability.

I'm not agreeing or disagreeing with you about the validity of cranking slightly longer (i.e. cranking w/o letting the grid heaters do their thing) because I honestly don't know. You made some interesting comments that made me think about what happens when you crank a cold engine.

 

I live in Edmonton, and I go out to my truck all the time in shorts and most nothing else to start or get something from my truck. Even in winter. But then again, I spent six months in a place where it never went below 40 celsius. Thats ABOVE freezing. So, it doesn't bother me that much.

 

Man, I would not have to worry about starting the truck with those temps, because I'd be a frozen block of ice somewhere. Those of you that live in those areas, more power to you. I couldn't keep a job there since I'd never leave the house, and my heating bill would put me in the poor house.

 

Mark,

I don't know what you mean by "grab the oil". The bearings already have oil in them at startup, they are not dry. Any rotation instantly builds an oil wedge and separates the bearing from the journal. When I say speed is not relevant I mean any speed associated with an engine, ie. cranking, running etc. A good example of a low speed oil wedge is a ship propeller shaft that may be turning at only 50 RPM or less. That shaft only has oil "present" but doesn't have oil pressure. It's support bearings are completely dependent on forming an oil wedge at very low speed, as is its thrust bearing that pushes the whole ship. Another is a train car axle bearing. Speeds of zero to 70 MPH with a very heavy load, and dependent on an oil wedge. Old farm engines are another example. Some worked all day at speeds as low as 100 to 300 RPM with no oil pump and only grease cups on the main and rod bearings. At least they had the thicker grease, but they only got a little bit once in a while. Piston rings must also ride on an oil wedge. They must scrape most of the oil off the wall to prevent consumption, but not so much that they gall. The oil wedge saves them. It's remarkable to me how little oil must be present to separate surfaces and prevent wear.



Wetspirit

 

HOW IS THE DEL VAC 1 WORKIN FOR YOU ??? I JUST BOUGHT IT FOR MY '05' 3500 DUALLY 4WD HAVE NOT PUT IT IN YET

 

Wetspirit,
What I mean by 'grab' the oil is that the rotating journal must 'grab' so that the oil wedge builds, and not just shear the oil withould building the wedge.

The bearings do not have oil in them at startup. Any non-pressurized journal bearing has metal-to-metal contact as soon as it falls below some minimum speed. The oil wedge does not get established instantly. How quickly it gets established is very strongly a function of rotational speed.

Speed is always relavent. I can design a bearing-oil system to be ring oil lubricated (or some other non-pressurized oil delivery system) that operates at very slow speeds, such as your referance to a 50 RPM ship propeller. Even these have a minimum speed that must be maintained to prevent metal-to-metal contact. At the same time some bearing-oil systems have operational parameters that result in designs that have minimum speeds (minimum oil wedge formation speed) that are much higher (can approach 1000 RPM). High speed motors and centrifugal compressors would be an example of this.

Again, it is not possible to maintain an oil wedge at zero speed. If the bearing is operating below its minimum oil wedge speed, it is doing so at the expense of having metal-to-metal contact. Some bearings, such as bushings operate with metal-to-metal contact by design. I don't think that the bearing in our engines are designed for that type of service.


As I stated before, I'm not saying that what you are doing does not result in less bearing/engine wear. It an interesting thought, and one that will cause me to 'study' the situation a little more. However, make no mistake, the bearings & oil are designed as a system to operate under a certain set of parameters. Perfect parameters can not always be maintained. Starting is one such time. So the effort is to determine how best to minimize damage/wear while operating in less than perfect conditions.

 

Your thermometer is broken . Our average lows in this area are not 20-25 below zero. You are right about being -40 though. It has happened 3 times in the last century. 2 times were before the Cummins was in use in the Dodge Ram.

This is good info for the people that live in areas where it is consistently below zero though. There are things we can all do to minimize the impact cold starts.

 

Well I live 18 miles south of the IA/MN state line and last winter we hit -30 below zero for 2 weeks and yet this year we have only been down to -15 below. But you being in Omaha you hardly ever see cold wether as you live in the Banana belt where it never gets cold

 

[QUOTE=Mark Hodowanec;1331351]Wetspirit,
What I mean by 'grab' the oil is that the rotating journal must 'grab' so that the oil wedge builds, and not just shear the oil withould building the wedge.

The bearings do not have oil in them at startup. Any non-pressurized journal bearing has metal-to-metal contact as soon as it falls below some minimum speed. The oil wedge does not get established instantly. How quickly it gets established is very strongly a function of rotational speed.

Mark,

Bearings do definately have oil in them at startup. Of course they do. Where did it go? Some will slowly drip out over time and less will be in the bearing after a period, but there is always oil there unless someone has used solvent to remove it and then re-assembled the engine, or it has been a very long time since it was run. And the presence of oil is what protects the bearings at startup. You mention no oil wedge at zero speed. Well of course that's true. No speed, no wedge. And no wear because nothing is moving. Again, "grab" the oil is a odd term. As you know, journal bearings in the Cummins are pressure fed. At startup the residual oil from the last run protects the bearing long enough to get the oil pressure up to ensure a constant supply. Automotive bearings do not run without oil and are not designed to run withut oil. If they do they are destroyed very quickly. It's the pressence of oil not the oil pressure that counts. The oil pressure only delivers the oil, flushes out the contaminates out and cools. The oil wedge is a phenomenon that occurs when oil is present between any two sliding surfaces, and happens as soon as there is movement. Gear teeth, journals, cam lobes, rings, turbo shafts, etc. all survive because of the oil wedge. And they don't just run for a while till the speed and conditions are right, it's as soon as they begin to slide in the presence of oil.
Your original comment was that cranking speed may not be high enough to form the wedge. It definately is. Of course it may not prevent metal to metal contact if the bearing is damaged or severely worn, but we'd better hope it does in a normal engine.

Wetspirit

 

I don't think so....

 

Why do you say that becasue I forgot to add that the temps were not official temps but what was shown by our Weather Channel/La Crosse Technology weather station probes here at my house. So being mine reported –18 below zero last night at my house and –18.6 below at my Uncles house about 3 miles north east of me, should I not believe either one because the closest airport Mason City only reported -17 below zero at 2:53 AM? Also I was not using temps with wind chill but if I was to add in wind chill for last night based on the temp at my house (from 8 mph wind that was recorded at the airport) we were at –35 below zero based on the Wind chill Calculator from the NWS.

Edit: I see made a mistake of I using the word average in the one post so I was wrong to use that word.