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.)

 

[RoyJackson]

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."

That "No Idling" thing is getting pretty common now...not sure if it's a good idea or just some of the EPA's idiocy.

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.)

Personally, if I'm going to be off the tractor for more then 5 minutes or so, I shut it down. Can't say I have a good reason to do this, but that's what I do.
BTW, I never idle the engine at less then 1500 RPM. Low speed idling isn't good for a diesel.

 

[20 20]

Most of the owners manuals I have read say 5min warm up period at a high idle 600-800rpms{gets the oil flowing}, then gradually work into a heavy load. I Also move hydraulics some before doing work especially on the excavators.

 

[k9american]

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.)

I'm not sure how this may apply to the small diesels, but Cummins says not to idle the 5.9 (as in the Dodge Ram) for more than 10 minutes max. That's from the horse's mouth at 1-800-DIESELS (Cummins). It has to do with decreased upper cylinder lubrication at idle RPM. The engineer I spoke with said 11-1200 and up idle is OK, hence the "fast idle kit" Jerry K mentions above.

I let the tractor - JD 4510 - warm up for about 5 minutes and cool down about the same. No loads until the gauge comes up. Pretty much what Roy said... except for the cigarette part. Quit 2 years ago (after 50 yrs) and would still really like to go out back and have a smoke RIGHT NOW. But I won't.

 

[oldballs]

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.

Maybe Roy figures that since there is smoke in the Deere's pipes, there ought to be smoke in his pipes.:laughing: Actually smoking is harmful to ones health. I smoked a cigarette in the 7th grade and never grew up over 5'4". (they say it'll stunt your growth):laughing: Seriously, the FEL and 3-pt just doesn't want to move until things get warmed up at little, even in the summer. But moving out to the work site in idle shouldn't hurt anything...I hope.

 

[RoyJackson]

Seriously, the FEL and 3-pt just doesn't want to move until things get warmed up at little, even in the summer. But moving out to the work site in idle shouldn't hurt anything...I hope.

No problem, as long as you don't put a load on the tractor (by "load", I mean any type of work other then moving the tractor...not just a load in the loader bucket).
As I'd written, keep your idle RPM up around 1500...easier on the bearings.

 

[Short Game]

A habit I developed has been to get into a "granny" gear and idle out of the tractor port. I guess it just makes me feel like I'm getting somewhere as the engine warms up. I would never have guessed that the idle, where it's set from the factory, could be detrimental. I spend hours at idle when I'm running my splitter. I don't need a 41 HP splitter. Now I wonder how many hours I'm taking off my engine's life. Is idling at 800 to 1000 RsPM that terrible with essentially no load?

And thanks to everyone for the interest in this question.

 

[bigbull338]

i always let my tractor warm up 2 or 3 mins,an cool down about the same depending on what we are doing.

 

[JDgreen227]

i always let my tractor warm up 2 or 3 mins,an cool down about the same depending on what we are doing.

I started a thread on cool-down somewhere here on TBN a month or so ago. BTW, the manual for my JD says to let it run at idle speed 1 minute after starting in warm weather and 5 minutes in cold weather.

 

[sweep]

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.

Roy, ......You place more importance and look out more for your tractors engine than your own body.

Ready to be flamed by the smokers...:thumbsup:

 

[JDgreen227]

A habit I developed has been to get into a "granny" gear and idle out of the tractor port. I guess it just makes me feel like I'm getting somewhere as the engine warms up. I would never have guessed that the idle, where it's set from the factory, could be detrimental. I spend hours at idle when I'm running my splitter. I don't need a 41 HP splitter. Now I wonder how many hours I'm taking off my engine's life. Is idling at 800 to 1000 RsPM that terrible with essentially no load?

And thanks to everyone for the interest in this question.

Agree with you that your method is a good one, I too drive out at idle speed and head toward my destination as the engine slowly warms up. We were probably all told a long time ago that idling was bad for a (gas) engine because the fuel not burnt would "wash down" and contaminate the oil. Not sure if the same is true for todays modern FI cars.

And, as for letting the engine idle while not actually moving, I tend to shut my tractor off if I am not going to have to move it elsewhere it within 2-3 minutes.

Another truth....if your engine is running and your vehicle is not moving, your effective fuel mileage is zero....but I figure a 2-3 minute idling period while I load the bucket with brush, angle the back blade, etc. is pretty minor.