Starting a cold diesel engine on half throttle?

[JohnDB]

Hi all

Question 1 of 2:

Do you think it's acceptable to start a cold diesel engine on half throttle? Its what the operator's manual recommends:

(This tractor is about 40 years old, 6 cylinder 2.6 litre IDI engine)

As soon as the engine fires I back off the throttle, but I still worry that it's not good for the engine. So instead I usually start it at idle setting, and with ambient temperature around 20 dec C / 68 deg F I need to preheat for about 20 seconds for an immediate start.

The operators manual recommends using glow plug under the heading "Starting the engine in cold weather", recommending 40 seconds of preheat, and 60 seconds of preheat if the temperature is below -15 deg C / 5 deg F. In both of those situations the manual also says to start on half throttle.

Question 2:

Will a different type of glow plug (assuming I can get one to fit my tractor) enable me to start the engine with the throttle at idle, with significantly less pre-heat time?

The NGK website refers to different types of plugs, with times to 800-900 deg C ranging from 25 seconds (probably my existing type of glow plug) to 4 seconds for a 2 coil self regulating plug.

(My current glow plugs are NGK marked "7812 Y-105-I 10.5V" and could be original. The numbers have been superseded, no info about it on the NGK web site. The WSM describes the OEM plugs as metal sheathed coil type factory spec is 1.0 to 1.2 Ohms, replace a plug if resistance is zero or infinitely large. Actual resistance for each one is 1.7 to 1.9 Ohms, so electrically I assume my plugs are OK.)

Thanks for reading this far, looking forward to your thoughts.

John

 

[GeoHorn]

Back in the early “60s… it was common for automakers to recommend starting the engines by pressing the accelerator-pedal to the floor. They failed to mention to release that pedal before turning the key to the ”start” position. (pressing the pedal to the floor set the new-fangled automatic-choke properly for a cold-start…but they didn’t mention that was the reason.)

I suspect your tractor manual is making a similar error.… (not regarding a choke…but regarding movement of the throttle lever would likely un-seat/re-seat an injector-pump/governor mechanism.)

If it were mine and me…. I’d do as you seem to prefer…start it at “idle” and let ‘er warm up a bit before putting it to work.… Especially if that technique works well consistently.

 

[GreensvilleJay]

My gut says this is to get the engine to START and RUN, in a short order of time. Common sense says to reduce RPM...that's 'written between the lines' of the manual....

Anyone that operates their machines on a regular basis KNOWs how they like to be started and run. I've got a well worn mid70s diesel forklift,it took me 3 years to figure out the perfect, never fail, starting proceedure, any day, any season and it ain't in the book !

 

[RalphVa]

We ran with diesel cars for 40 years and now with diesel tractors since 2004 and diesel generator since 2012. In cold weather, ALWAYS put the throttle up about 1/2 way. Let up on throttle once it starts to a slightly fast idle or at idle. All Benzes and JDs shuddered upon starting and took a while to even out, but the Kubota B, Isuzu and VW TDI start evenly. Both the Isuzu and TDI have absolutely no diesel clatter or shake on starting cold. Very slight on the Kubota.

Think it's harder on the engine if you start, shudder and stop a few times rather than just start and run at higher throttle setting. Certainly harder on the starter.

 

[GeoHorn]

My gut says this is to get the engine to START and RUN, in a short order of time. Common sense says to reduce RPM...that's 'written between the lines' of the manual....

Anyone that operates their machines on a regular basis KNOWs how they like to be started and run. I've got a well worn mid70s diesel forklift,it took me 3 years to figure out the perfect, never fail, starting proceedure, any day, any season and it ain't in the book !

Mid 70s is before they taught forklifts how to READ.

 

[Botamon]

My 60 year old John Deere 2020 diesel has always started just fine with the throttle set at its lowest position (idle). Especially with how thick the crankcase oil is in cold weather, I would never cold start it at anything but an idle.

 

[RalphVa]

My 60 year old John Deere 2020 diesel has always started just fine with the throttle set at its lowest position (idle). Especially with how thick the crankcase oil is in cold weather, I would never cold start it at anything but an idle.

Change out to a 0w or 5w or 10w30 instead of 15w40 goo. It will crank 60-80% faster.