Deere 2720 Smoke issue at startup

[jsb2b]

I vote for checking voltage to each glow plug and if OK, bench testing the glow plugs. They don't last forever.

 

[Deere Dude]

I vote for checking voltage to each glow plug and if OK, bench testing the glow plugs. They don't last forever.

I have a X740 and at 650 hours it had symptoms like the OPs 2720. It was 2 glow plugs. Easy to test.

 

[Dwellonroof]

I would work it very hard for a while then see if it cleared up.

 

[Dwellonroof]

The 2720 doesn’t have glow plugs but an intake heater.

 

[Jims1025R]

I had this with my brand new 1025R. I accidentally found the solution for my tractor, plug in the block heater. When it is warmed up before start, it does not smoke at all.

 

[John0829]

Question is what is the ambient air temp when it does this?

 

[Deere Dude]

The 2720 doesn’t have glow plugs but an intake heater

Parts search shows 3. The OP will have to confirm.

https://partscatalog.deere.com/jdrc/navigation/equipment/67836/srch/GLOW%20PLUG

 

[Tx Jim]

Item 34 appears to be glow plug & described as so.

 

[Rob REECE]

Hi everyone,

Before I go and pull the head off of this thing I wanted to see if there were any other ideas. My 2720 is absolutely belching out smoke at cold start and kinda rumbles a bit, almost like it's not running on all cyls - it smells like unburnt diesel. It does clear up once up to operating temp and the tractor seems to run just fine with plenty of power. My first thought was stuck injector. I pulled the injectors, they didn't look great, at least to my untrained eye, so I replaced them. No effect.

Then I checked the valves - they are all within spec and no oil is getting by the valve seats. It "Smells" literally like a fuel issue, but I'm not sure what else it could be? I was thinking of pulling the head to check for scoring, like if there was a bad ring where oil was getting by, but it doesn't smell like burning oil to me - it smells like fuel. Any thoughts would be appreciated.

Contact a John Deere dealer. If it is a diesel it sounds like it is normal for them to smoke and run rough at startup.

 

[Bentrim]

Diesels are a compression ignition engine. When starting if the fuel does not burn completely you will get white smoke, really unburned diesel fuel. This is due to the "cold" combustion chamber. This can be caused mostly by the design of the combustion chamber, and the type of injection. Usually direct injected engines start faster with less smoke, those that use pre-combustion chambers (indirect injection) are harder to start and will smoke more than direct injection. Indirect injection engines are quieter and are easier on parts than direct injection engines as they are noisier and need stronger parts.
The best way to eliminate smoke is to preheat the glow plugs (if equipped) be sure the manifold heater is used correctly (if equipped) or even us a block heater to preheat the engine.
As an engine ages the injectors usually lose set pressure and the nozzle wears or gets dirt in it so you took care of that when you replace the injectors. Unless the injection pump is not timed properly it will usually have no effect on starting or smoke. If timing is off it may have starting issues and just not run right. Also as the pump wear it may not make enough pressure to start the engine but may run OK if it is started.
If you feel you have an issue with the engine -- Listen to it -- When trying to start it listen very carefully as it turns over -- Does it turn over even or does it sound like one cylinder is "easy"? Also when it starts does it seem that all cylinders are creating the smoke or does it "puff" as just one cylinder is off? if these issues appear you need to repair the "compression" as you have a weak cylinder or two. Loosening a high pressure line at the injector will also help diagnose a problem, just like pulling a plug wire on a gasser.
Most of the engines used in compact tractors and other small equipment are of the indirect injection, they can be made lighter, and are quieter than direct injection. So I suspect this issue cannot be eliminated in this tractor. By the way the rumbling you speak of is the fuel burning slowly and incompletely, of course as the combustion chambers warm up the smoke and noise disappears.
I have been working on diesels for over 50 years and have seen some that would not start at over 95 degrees without glow plugs, some that when started looked like it was a smoke machine for about 15 minutes and some that would start with no help at 25 degrees, that one smoked but it started with no assist (no heating, no ether) But be aware these common rail systems are a beast of their own. They use extremely high pressure to inject the fuel and can do so in many timed injections. Also due to the high pressure they atomize the fuel better for cold starting.