Some friends and I were talking about diesel engines and one was surprised to hear that diesel engines remain idling during cold weather with the recent price of fuel. When questioned we thought that the answer was due to several factors such as: 1. Diesel engines don’t have anti-freeze so they’d freeze up if not kept running and 2. Diesel engines in cold weather are hard to start due to cold oil in the sump. Can any of you confirm/deny the reasons stated above for keeping diesel engines idling in cold weather or add any others we may not know about. Thanks.
I believe that Diesel fuel has a higher freezing point then gas. #2 turns to jelly if left in superlow temperatures, so there’s actually a heater in the fuel tank or some such and by running the engine it doesn’t get a chance to gel up.
I may be full of it on that though.
The engine is left idleing because (1) they do not have anti-freeze, (2) the cost of fuel is cheap compaired to haveing a locomotive down for freeze up i.e. the engine block could crack and the whole engine has to be replace.
Rodney
The newest engines monitor their coolant temperature, the brake air pressure and such, and will start themselves should one of the variables fall below the prescribed minimum. They will then run until everything is back to the prescribed levels and shut themselves off. Warning lables on these engines warn that they may start unexpectedly, and there is also a buzzer that indicates the engine is about to come to life.
No, you’re very close. There are 3 main worries. One is the coolant freezing. Antifreeze isn’t generally practical in EMD and GE engines because of how likely water leaks are versus the damage caused when antifreeze gets in the lube oil.
The two other reasons are the fuel. Diesel fuel has two critical temps to worry about - the cloud point and the pour point. The cloud point is the temp where parafin (wax) in the fuel crystalizes. You can spec the cloud point to be lower in the winter, but it’ll cost you more for the fuel. The fuel will still flow, but the parafin crystals will clog the fuel filter.
The pour point is the temp the fuel turns to a gel and won’t flow at all. You can spec the pour point, too, but the lower you spec it, the more it costs you. The most common method refiners use to reduce the pour point is blending with #1 fuel oil (kerosene and/or jet fuel).
Even with the engines left idling, keeping the fuel system happy requires some technology. The engines all have fuel pumps that supply a steady flow to the engine with significant return to the tank, even when in notch 8. This flow is warmed by passing thru the injectors (high pressure pump on GEs) before going back to the tank. In very cold climates, this is not enough to keep the fuel in the tank above the cloud point, so most road use fuel preheater which are heat exchangers between the fuel suppy line (upstream of the filters) and the engine cooling system. UP also uses a “hot well” partition in the fuel tank to keep the fuel near the suction line warm. The fuel return l
I really do hate having to get out of my nice warm switcher to go around and start all the engines around our shop when it starts to get cold, but in turn i also hate having to put them back in the shop because trhey got too cold and dumped their water.
[quote user=“oltmannd”]
No, you’re very close. There are 3 main worries. One is the coolant freezing. Antifreeze isn’t generally practical in EMD and GE engines because of how likely water leaks are versus the damage caused when antifreeze gets in the lube oil.
The two other reasons are the fuel. Diesel fuel has two critical temps to worry about - the cloud point and the pour point. The cloud point is the temp where parafin (wax) in the fuel crystalizes. You can spec the cloud point to be lower in the winter, but it’ll cost you more for the fuel. The fuel will still flow, but the parafin crystals will clog the fuel filter.
The pour point is the temp the fuel turns to a gel and won’t flow at all. You can spec the pour point, too, but the lower you spec it, the more it costs you. The most common method refiners use to reduce the pour point is blending with #1 fuel oil (kerosene and/or jet fuel).
Even with the engines left idling, keeping the fuel system happy requires some technology. The engines all have fuel pumps that supply a steady flow to the engine with significant return to the tank, even when in notch 8. This flow is warmed by passing thru the injectors (high pressure pump on GEs) before going back to the tank. In very cold climates, this is not enough to keep the fuel in the tank above the cloud point, so most road use fuel preheater which are heat exchangers between the fuel suppy line (upstream of the filters) and the engine cooling system. UP also uses a “hot well” partition in the fuel tank to keep the fuel near the suction line warm.&
[quote user=“chefjavier”]
[quote user=“oltmannd”]
No, you’re very close. There are 3 main worries. One is the coolant freezing. Antifreeze isn’t generally practical in EMD and GE engines because of how likely water leaks are versus the damage caused when antifreeze gets in the lube oil.
The two other reasons are the fuel. Diesel fuel has two critical temps to worry about - the cloud point and the pour point. The cloud point is the temp where parafin (wax) in the fuel crystalizes. You can spec the cloud point to be lower in the winter, but it’ll cost you more for the fuel. The fuel will still flow, but the parafin crystals will clog the fuel filter.
The pour point is the temp the fuel turns to a gel and won’t flow at all. You can spec the pour point, too, but the lower you spec it, the more it costs you. The most common method refiners use to reduce the pour point is blending with #1 fuel oil (kerosene and/or jet fuel).
Even with the engines left idling, keeping the fuel system happy requires some technology. The engines all have fuel pumps that supply a steady flow to the engine with significant return to the tank, even when in notch 8. This flow is warmed by passing thru the injectors (high pressure pump on GEs) before going back to the tank. In very cold climates, this is not enough to keep the fuel in the tank above the cloud point, so most road use fuel preheater which are heat exchangers between the fuel suppy line (upstream of the filters) and the engine cooling system. UP also uses a “hot well” partition in the fuel tank to keep the fuel nea
Let us not forget the most important reason, to keep the cabs warm, so the toliets don’t freeze. [:)]
Nick
That can get ugly !!! Especially if they have the Microphor toilets!
Conrail used to put antifreeze in the toilets!
Frozen toilets aren’t too messy. It’s when they start to thaw…[:O]
Can you say EEEEEWWWWW!
I remember anti-freezing the toilets. My current employer doesn’t. Randy can probably answer this better, But I’m pretty sure antifreeze doesn’t work with the Microphoe units.
Nick
My current employer had other toilet issues…[
]
Those Micorphot toilets are like little sewage treatment plants on wheels. I think you’re right about antifreeze - it’d kill the little digester beasties.
The microphors had immersion heaters to keep the water from freezing in the freshwater tank . The reliability of the heaters was dubious , when they froze they naturally expanded… expanded into the electrical cabinet , cab, cab heater pipes etc. They were most difficult to remove from older GE’s as they were jammed between the rear cab wall and the main electrical cabinet wall… oh and they are made of stainless steel … forget about cutting them out !
There is still anti freeze in the crappers , just not glycol , still hurts when it splashes on your parts.
At one time is was said that the worst thing you could to do a diesel engine was to start it. So, the wisdom was, once you get it started, never turn it off…with one or two exceptions, such as critical maintenance. The reasoning was that rebuilding/replacing a damaged diesel was much more costly in the long run than letting it idle for hours. The internal parts would take a beating much like a gas engine does on start-up before tolerances are improved by the right temps and before lube can coat all the appropriate surfaces.
Has the technology changed sufficiently that this is no longer an issue?
There is also the matter of the air brake system in the cab. If the air freezes up the brakes will do goofy things, or not work at all. There are a number of check valves beneath the floor that can get jammed with even small pieces of ice on the lines. If the moisture traps (spitter valves) on the main res don’t work so good, or the crew shuts them off, the ice in the lines gets worse.
I know this is a family forum, but a (cough, cough) ceramic privy (cough, cough) is considered the height of engineering overdesign, and some males of the human species with overactive imaginations use that metaphor to describe some females of the human species such as a certain Mr. Lionel Ritchie who had a hit song about a fired-clay structure.
But stainless steel. Forget about brick! Something that dulls cutting tools and only softens when exposed to a torch. Is the GE locomotive stainless-steel commode going to provide a new metaphor?
My understanding is that modern diesel engines have an electric lube oil pump. The pump is supposed to be run a few seconds before cranking the engine making sure that the bearings are properly lubricated. In addition to reducing wear, this also reduces the torque needed to start the engine.
Okay, that makes sense. The pressurization of the main lube system prior to start-up would reduce wear considerably. Thanks, erikem.