Diesel Warm-Up -- How Long -- Why?

[Short Game]

How long should we be warming up our small diesel engines?

Why do you say so?

I've known people who have had widely varying opinions on this. I don't know what's best, but I would like to.

 

[Willl]

Diesel fuel flash points vary between 126F to 204F, depending on which graph you read.

Our diesel engines generate about 400 psi cylinder pressure.

And using this chart on air/pressure temp, I've come to this scientific conclusion.

If I'm not cold; no preheat. If I'm cold; 10 sec preheat. If my B's are cold; 20 sec preheat.

 

[wedge40]

So if you're wearing thermal underwear it's only a couple of minutes?

Wedge

 

[JDgreen227]

How long should we be warming up our small diesel engines?

Why do you say so?

I've known people who have had widely varying opinions on this. I don't know what's best, but I would like to.

In spring, summer, and fall, I start my Deere 4210 and let it idle in the barn for 2 or 3 minutes, then raise the rpm's to 1400-1500 and drive toward my mowing area, when the temp gage starts to move into the lower third of the scale (about 5 min) I engage the mower pto and raise the rpm to 2200. In cold weather, I give it a 5 minute warm up before backing out to move snow. I like to see the temp gage in the lower third before moving snow.

Interesting thread, very good subject matter ! :thumbsup:

 

[Swiftriver]

When I bought my first diesel powered toy, an old JCB backhoe, an old timer told me to make sure I let it warm up before I put a load on it or I would score the cylinder walls.
I agree. Definitely good subject matter. Is what I was told true?

 

[MFRED]

Let it warm up & let it cool down too. Don't be afraid to expand the practice to non-diesel pieces too. Helps everything heat & cool at the same rate. Your pistons, where the heat will start, are going to heat faster than the connecting rod/crank, oil and such.

You warm yourself up before a workout, you should do the same with equipment.

Gotta love it when people start a machine dead cold & put it to the floor.

 

[JerryK]

One note about warming a diesel up. Most modern diesels do not create much 'heat' at low idle. Us Cummins owners install a 'fast idle' kit that idles at around 1200 RPM. [ some enable a three cylinder idle, but that is another story ]. I 'fast idle' idle my tractors for a few minutes, then take them for a low speed cruise [say 1600RPM or so, non-motor lugging] for awhile to actually load the motor some to help it heat up. Ditto on the above post about cool down...

 

[RoyJackson]

I'll idle the Deere at 1500 RPM for about 5 minutes (long enough to smoke a cigaret), then go to work...
No load on the tractor until it's at normal operating temperature though.
Same thing I've done for the last 10-11 years.

 

[houstonscott]

I was in Coast Guard for thirty years and operated diesel engines in small boats. We always kept engines heated for search and rescue. All the parts in an engine are designed to run at a certain temp. They are designed to change shape as they heat up to the shape/size they are to be when making power. So avoiding high rpm's until engine comes up to temp is important for long life of any engine. A cool engine is not in the tolerances yet for full power, and they are designed to change size and shape as they heat. It will do it but you increase wear and shorten life of engine and parts.

HS

 

[DAY]

Sub-question on this topic:
Traditionally, diesels were 'never' shut down; I remember truck stops that sounded like a family of snoring giants.
But I recently saw a sign at the Uline distribution center that says "no diesel idling."

How long do you/should you let it idle, while you tend to other chores? (I assume it was considered "bad" for the engine to stop and start it often.)