M7040 glowplugs

[tom4018]

I have a 2008 M7040, this morning in the upper 20's glow plugs ran 5 or 6 seconds guessing. I run the Rotella 5W-40, started doing that in a Ford I had before and saw better cranking speed in cold weather. Parts manual shows several relays in the dash panel.

 

[wmonroe]

You know there is a hole there...and I've poked around in that hole trying to find a screw head...nothing. Because if the steering wheel you cannot see into that hole. So...how far into that hole is the screw...and can you see the screw head?

On mine the screw head is easily visible, it is a hard area to see and I usually use a stubby screwdriver to get the screw out, but I haven't had trouble getting on the screw. Maybe request a parts diagram from messicks and see if there is a fastner you are missing.

 

[whis]

Big difference in 6 degrees and 20. glow plugs might not be working, but it won't make motor spin faster or slower

 

[jcummins]

Well I called the local dealer, and asked how to get the dash off. He said there is a nut you access on the outside of the firewall. I said, no...I looked, he said look again. Come to find out, there was a small rectangle of mylar tape type stuff stuck on the firewall...same color as firewall, not noticeable. I had to destroy it to get to the nut....then realized the hood has to come off. Just no way to get to it.

With the hood off, I could also get to that 'Charge glow plug' as Kubota calls it on the outside of the firewall...it tested good. I pulled the relays, they are good. Also with the hood off, I could also get to the electrical connect to the glow plugs on top of the motor. Using a test light I found the relays got power at the detent position of the key between the ON and START position. The charge glow plug got power at the START position, also the glow plug connection on top of the motor got power at the START position? I do not understand why no power to at least the charge glow plug at the detent position on the key.

NOW this morning it was 7 degrees and I hoped the insulated barn would be below 32...it was right at 32 degrees. Turned key to ON position, the glow plug light came on for about half a second??.. so those who posted the glow plugs don't come on until 32 degrees are right. The dealer said yesterday that was NOT true, so much for what the dealer knows.

The glow plugs work, but some nagging questions:
WHY 32 degrees when every diesel I've ever had, the glow plugs come on at a much higher temperature? Those that mention this do you have some documentation I could read on it?
WHY does the glow plugs come on so very briefly at 32 degrees when every other diesel the glow plugs cycle for several seconds?
WHY do the glow plugs come on with the key in the ON position this morning, because when I tested when the relay turns on and found it got power at the detent position which is between the ON and START position.
WHY does Kubota's documentation from the WSM manual, shown below, showing the glow plug relay but nothing... nada... about the Charge glow plug as Kubota calls it, which is between the relay and the glow plugs?

 

[jcummins]

BTW my last post wasn't clear on this, but from my testing, it appears the glow plugs come on at any temperature....at the point the engine cranks. No glow plug light coming on.

 

[Tx Jim]

In my M7040 operators manual on page 14 it states:Suppose that the engine coolant temp.is not high enough yet. The glow plug ind.(4) also comes on when the key is turned to on to preheat the engine and goes off automatically when preheat is completed. Illumination time of indicator varies according to the coolant temp. On page 15 it states:If ambient temp is below 0 C(32F) and the engine is very cold activate glow plugs.

 

[jcummins]

In my M7040 operators manual on page 14 it states:Suppose that the engine coolant temp.is not high enough yet. The glow plug ind.(4) also comes on when the key is turned to on to preheat the engine and goes off automatically when preheat is completed. Illumination time of indicator varies according to the coolant temp. On page 15 it states:If ambient temp is below 0 C(32F) and the engine is very cold activate glow plugs.

Thanks TxJim....I actually missed that in the manual. But still...what's magical about 32 degrees when other diesel glow plugs work very different....my ZD326 being one of them. Whether the plugs are working....my testing confirms they are, ....but I'd still like answers to the WHY it works the way it does.

 

[Tx Jim]

I suppose because the engine is direct fuel injected and the engineers thought GP's weren't necessary until at/or below freezing temps. I use my M7040 to feed/load rd bales and I know it starts very easy without the aid of GP's at just above freezing. I have no electricity in tractor shed so this is without the aid of the coolant heater. I've had experience with 2010 D with "INDIRECT fuel injection" and they were hard starters at 60 degrees with GP's activated.

 

[jcummins]

TxJim what oil do you have in your 7040?

 

[Tx Jim]

15W-40 but I live in Texas where most of the time it doesn't get below freezing.