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

   / Diesel Warm-Up -- How Long -- Why? #51  
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.

Let it heat up till the idle drops to normal. Most newer tractors will idle fast when cold till they reach operating temp. If I have been working the tractor hard I give it 5 minutes low idle before shutdown. May even raise the hood on a hot summer day.
 
   / Diesel Warm-Up -- How Long -- Why? #52  
Great thread! I've wondered what is best on this too.

It's interesting. I have a Kubota M7040. It's the first diesel tractor I've owned. I have to work the thing pretty hard to get the engine to the point where it's too hot to touch. Not that that's an indication of anything important, just thought these things would get hotter faster, like a gas engine.

The manual for mine indicates what most people have indicated, when cold let it warm up. If really cold (ex. 0 degrees), let it warm up 20-30 minutes. Problem with that is, if I'm running the machine at that temp, it's because it just snowed out and I'm up at 5am trying to clear the driveway so I can get to work. It still let it warm up though, 10 minutes or so. And the 7 foot blade I use to move snow doesn't even make the engine work, so I'm not worried.
 
   / Diesel Warm-Up -- How Long -- Why? #55  
yeah that does seem long. even in winter when i was hauling a tractor out of a few states north, I only warmed her long enough to get a coffee and danish and drain the lizard at the service plaza we pulled over at for the night.
 
   / Diesel Warm-Up -- How Long -- Why? #56  
Some places the Diesel will never warm up at idle.:thumbsup:
 
   / Diesel Warm-Up -- How Long -- Why? #57  
Equally important is a 5 minute cool-down on turbo diesels particularly direct injected (DI) turbo diesels for a 2 reasons.
First & most obvious is to cool the turbo to prevent the residual oil from sitting in the center section (bearing housing) and burning thus turning to thick tar that can block lubrication passages and build up as varnish on bearing surfaces.
Second direct injected diesels have the injectors injecting fuel (fire) directly onto or into the piston bowl. These engines typically have piston cooling nozzles cooling the underside of the piston removing excessive heat as long as the engine is running.
Shutting a DI diesel down immediately (which no-one here would intentionally do) after a prolonged hi power run can cause severe piston scoring for the following reason.
Immediately upon what we called a hot shutdown (engine stall) the internal engine temperatures start to rise causing piston to cylinder clearance to diminish because the coolant & oil flow no longer can remove the heat resulting in excessive and uneven heat buildup causing (aluminum) pistons to grow becoming tight in the cylinder. This situation will create a piston/cylinder score if the engine is turned over before the temperature stabilizes and engine cools.
If the engine can be promptly re-started within seconds (great) otherwise a 30 minute cool-down should be observed to prevent damage.
These first hand observations were with Cummins VTA-903 V8 engines rated at 500&600hp installed in test cells for testing of transmissions installed in the US Armies Bradley Fighting Vehicle System.
We had several failures until we implemented this procedure.
Tim
 
   / Diesel Warm-Up -- How Long -- Why? #58  
Wow. Totally miss read OPs original question. My bad.
 
   / Diesel Warm-Up -- How Long -- Why? #60  
Some places the Diesel will never warm up at idle.:thumbsup:

even with an idle up solenoid working?

soundguy
 

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