Preheating glow plugs on a John Deere 4100

[JFahey]

I bought a model 4100 deere that is pretty hard to start. I am not sure how to preheat the glow plugs on this tractor. I tried pushing in on the key, but it will not budge. Cranks for about 15 or 20 seconds in 60 70 degree weather before it fires up and smokes like crazy for a little bit. After it has been running it fires right up. Any help is greatly appreciated.

 

[WranglerX]

Maybe a clue at this link...

41 Glow Plug CONTROLLER

Dale

 

[Roadworthy]

In the Operator Manual, under Starting the Engine, Item 12 it appears the glow plugs should heat automatically for three seconds. You turn on the key, wait three seconds, you'll hear a click, then start the engine. The key does not push in and glow plugs are automatic, just wait three seconds before hitting starter - oh, and turn the fuel on: Operating

 

[kennyd]

Pull up the PTO switch or place the range selector in H or L, the turn the key to START, for 3-5 seconds if the safeties are active then the starter will not crank but the glow plugs will light (if they are good). On the 4110 model (I owned one for 12 years) the glow plugs where active ONLY when the key was in the start position while cranking, the 4100 was the model just before the 4110.

But, you should check the plugs with an ohm meter to ensure they are still good.

 

[Roadworthy]

Depending on the type of plug an ohmmeter may not tell you whether they are good. It is not uncommon for the element to short to ground when the plug fails. In this case it may read good even though it is not. Most ohmmeters are not precise enough to differentiate between the low resistance of a good glow plug and the even lower resistance of a shorted element. Many glow plugs do not run on twelve volts. They depend on the controller to deliver a lower voltage or a series dropping resistor to drop the voltage.