[Punch_Master]

I've got an older (93) F250 with the non-powerstroke 7.3 diesel engine. I bought it last year, and my question is how long should I let the truck "warm up" on cold days before driving it? I don't mean super-cold, just 30 to 50 or so. I've been letting it run at fast idle for a minute or two, but wonder if this is necessary. It usually drops out of fast idle after a few minutes of driving. Thanks!

I've always been told that the longer you warmup any Diesel before you put a load on the engine the better off you are. Remember one thing, a normal Gasoline engine contains a total of 5 quarts of lubricant to get to operating temp. A diesel holds around 15 quarts or approximately three times as much oil to heatup.

 

[curverbowruss]

I am by trade a service tech. for Caterpillar in the earthmoving field mainly. The design features of the newer "Power Stroke are very different from what I will call a "direct Injected" engine. A diesel engine by design works at its' best under a load. The engine will work at its' optimum under a load and, at the manufactures engineered temp. parameters. The fuel is ignited by shear compression of the air fuel mixture unlike a gasoline engine in which uses a spark ignition. By applying light loads until the engine is at temp.(some engines at about 180 degrees and, many others at about 210 degrees) will allow for better fuel economy. If one notes in cold weather that the newer "Power Sroke" engines will all by themselves pick up engine speed all on their own--known as elevated idle--this is the electronics doing this to bring the engine up to temp.. The newer engines I call HEUI--This is Hydraulic over electronic unit injection where the engines use crankcase oil pumped under very high pressure through a common rail in a manifold and, also fuel is pumped through in a simular manor. The oil actually is the power to actuate the injector instead of rocker arms and, pushrods. The electronic signal to each injector is the duration in which a spill port remains closed forcing the fuel to have to exit via the injector tip. The on board computor does this in micro seconds. Also the on board computor is programed in such a way that if one injector becomes weak the computor in turn will adjust or, increase the duration to the other injectors so as to maintain what is called the target rpms. All of this happens without the operator even being aware of what is happening until badly worn components are not able to do their jobs any longer. These internal parts such as your high pressure oil pump and, injectors are working hard. This is why you will hear many tell you that oil type, quality and, oil change intervals are critical on these engines. On the off road engines I work on alot many of the issues I encounter are due to maintenance issues where oil changes are not done regular and, also poor quality fuel filtration. Over all for the amount of fuel burn't to obtain power and, motion is far more economical than a gas engine. However todays electronic diesel engines require a strict fuel and, oil cleanliness practice. The direct injected engines with a normal injection pump and, pencil injectors are far more tolerable. The only thing is however is that with todays low sulfer fuel in which was a lubricant in affect--there are other chemicals that are in place to provide lubricity for the internal workings of the injection pump. My advice is to allow the engine to get the oil working through the engine and, a little run time. Then drive off. Also prior to shutting the engine down for the turbo charger--allow a short idle period. By the way I know you asked a simple question and, I have posted a Readers Digest version with information you may not even care about--just thought I would throw in a little info.

 

[alldiesels]

I let mine warm up more than needed but 3-5 min is more than enough. Every obs(95-97) psd I work on gets a 6pos chip with a high idle setting that lets them warm up really fast.
robert