Glow plugs taking longer to come on?

[guidedfishing]

I have a L4400 HST. When I turn the key to initiate the glow plugs sometimes they come on in a few secs, sometimes as long as 10 sec's before I see the panel light up and hear it engage. I thought it was the glow plug relay and replaced that but did not change they amount of delay. The amount of time definitely seems to vary, but overall it has been getting longer and longer when they used to initiate as soon as I turned the key.

The Battery is full charged. Before I start replacing the starter relay or the OPC timer switch wondering if someone could give me some way to confirm what I may be dealing with.

Thanks

 

[North Idaho Wolfman]

Have you tested the glow plugs?

 

[BruceP]

The amount of time definitely seems to vary, but overall it has been getting longer and longer when they used to initiate as soon as I turned the key.

TOTALLY NORMAL!! (I am assuming your engine STARTS OK... just the glow-time changes)

When you say "glow plugs come on"... you are misunderstanding what is happening....
When you turn the key, the glowplugs come on IMMEDIATELY... then the indicator comes on AFTER the glowplugs are up to temperature.

The ambient temperature controls the glow-time.
colder=more glow time

Lets not forget that the PURPOSE of the glowplugs is to preheat the engine so it starts in cold ambient temperatures.

 

[guidedfishing]

TOTALLY NORMAL!! (I am assuming your engine STARTS OK... just the glow-time changes)

When you say "glow plugs come on"... you are misunderstanding what is happening....
When you turn the key, the glowplugs come on IMMEDIATELY... then the indicator comes on AFTER the glowplugs are up to temperature.

The ambient temperature controls the glow-time.
colder=more glow time

Lets not forget that the PURPOSE of the glowplugs is to preheat the engine so it starts in cold ambient temperatures.

Yes engine starts fine, that makes total sense. but it is my understanding with the L4400, that when I turn the key left and the light indicates the glow plugs have turned on. Its a 2009 and regardless of the ambient temperature they come on immediately until recently they are taking longer to turn on, once on I give them a count of 10, then turn the key the opposite direction to kick the starter over, and it kicks right off.

What I am saying is happening, is when I turn the key to the left to start the glow plugs signified by the light coming on that it is taking much longer for the relay to kick the glow plugs on. Once the glow plugs come on I give it a 10 count and turn key the other way and it starts right up.

I hope that makes some sense. What I believe is happening is the glow plugs are taking considerable time before they even kick in.

 

[guidedfishing]

Have you tested the glow plugs?

I have not, can I do that with a multi meter?

 

[North Idaho Wolfman]

I have not, can I do that with a multi meter?

Yep disconnect any lead or buss connected to them, and measure the resistance, should be 1.5 to 2.5 ohm or anything close, more resistance or Infinite, then it's got a bad glow plug, save some future abuse replace all of them at the same time!

 

[BruceP]

I hope that makes some sense. What I believe is happening is the glow plugs are taking considerable time before they even kick in.

Perhaps you are correct. I am not familiar with EVERY Kubota glowplug system. The two I am aware of are:

1. Some machines allow the USER to 'manually' control the GPs (and count off the seconds) then start engine.
2. Other machines simply 'glow' them based on ambient temp.... then turn on dash-light to tell operator to crank engine.

From your description, your machine is type #1 above.

 

[Mark_BX25D]

From your description, your machine is type #1 above.

Or, possibly, he's got #2 and has misunderstood the operation?

 

[number two]

Perhaps the ignition switch is failing.
Not providing power to the glow plugs-hence no glow plug light on the dash.
Good Luck!

 

[guidedfishing]

Yep disconnect any lead or buss connected to them, and measure the resistance, should be 1.5 to 2.5 ohm or anything close, more resistance or Infinite, then it's got a bad glow plug, save some future abuse replace all of them at the same time!

Awesome, will do. thanks

 

[guidedfishing]

Perhaps the ignition switch is failing.
Not providing power to the glow plugs-hence no glow plug light on the dash.
Good Luck!

Thank you, I will check that out as well.

 

[guidedfishing]

Or, possibly, he's got #2 and has misunderstood the operation?

definitely number 1, its a manual process, and once triggered the dash light comes on immediately while I give it a 10 count. At least it did, before they trigger and I can hear the audible click when it does takes as long as 10 seconds before they turn on.

 

[ve9aa]

Don't be fooled by a light.

In my line of work, we "confirm the customers complaint" (or otherwise we sometimes get led down a rabbithole.!...the worst one is "it always used to do that" (only to find out later than such-n-such model or software version doesn't even HAVE that!)

First, you could measure to see if/when/for how long, voltage is reaching your glowplug bus bar.

Set your multimeter up to measure volts.
Put alligator ends on your meter leads.
Black goes to hard parts on the engine or chassis with an alligator clip.
Red lead goes to one of the glow plugs (doesn't matter which one...they're in parallel on most tractors)
Do all your "key" things as normal and watch the meter.
Does voltage reach the glowplugs when you want or expect it to?
If yes, you may have a wonky/corroded/loose lightbulb socket or something else in the nanny system (I don't know your tractor)

If you suspect the tractor is not starting well (ie: it's cold and normal glowing (whatever normal means to you) is not producing an easily started tractor THEN you'd want to start measuring resistance of glow plugs....eventually unhooking them and Ohmming out each one (they're in parallel, so the initial resistance check will really only tell you if AT LEAST one is good, not if ALL are good.

Please report back

 

[guidedfishing]

Don't be fooled by a light.

In my line of work, we "confirm the customers complaint" (or otherwise we sometimes get led down a rabbithole.!...the worst one is "it always used to do that" (only to find out later than such-n-such model or software version doesn't even HAVE that!)

First, you could measure to see if/when/for how long, voltage is reaching your glowplug bus bar.

Set your multimeter up to measure volts.
Put alligator ends on your meter leads.
Black goes to hard parts on the engine or chassis with an alligator clip.
Red lead goes to one of the glow plugs (doesn't matter which one...they're in parallel on most tractors)
Do all your "key" things as normal and watch the meter.
Does voltage reach the glowplugs when you want or expect it to?
If yes, you may have a wonky/corroded/loose lightbulb socket or something else in the nanny system (I don't know your tractor)

If you suspect the tractor is not starting well (ie: it's cold and normal glowing (whatever normal means to you) is not producing an easily started tractor THEN you'd want to start measuring resistance of glow plugs....eventually unhooking them and Ohmming out each one (they're in parallel, so the initial resistance check will really only tell you if AT LEAST one is good, not if ALL are good.

Please report back

Will do, once the glow plugs kick in, and I hold them on for a 10 count it starts right up. So the starting is not the issue, and I assume the glow plugs are working (but plan to check them) since it starts burns clean after I cycle them.

Its getting glow plugs to turn on, or my presumption that they are not turning on right away when I try and cycle them. Sounds like I have some work to do to track it down. Hopefully this weekend I can get some heat in the pole shed and do some checks.

I blindly changed the glow plug relay, and realize now I need to better isolate the issue instead of just randomly replacing parts.

Appreciate the input, now to chase it down with the volt/ohn meter.