Glow Plug Switch Question????
Post Fiend
Joined: Dec 2010
Posts: 10,121
Likes: 3
From: Orrville, Ohio
My understanding of the PCM function is that it already does this. 140 degree engine oil temperature and above (PCM doesn't pay any attention to coolant temperature) it won't run the GP's.
Thread Starter
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Fleet Mechanic
Joined: Oct 2006
Posts: 1,386
Likes: 1
From: Spokane, WA
I wouldn't rule out the possibility. This is why, if you're gonna do a workaround, probably the most useful one would be a regular SPST toggle switch (not a momentary) in _series_ in the wire going from the relay to the PCM. Leave it in the ON position, the plugs cycle as they would normally, the PCM will turn them off long before they overheat or carbon up or whatever. But for those runaround-town trips, when you're starting an already warm engine, you can flip the switch OFF. Flip it back ON when you get to your final destination, so that next time, when you start cold, it'll cycle as usual.
Hmm, this gets me thinkin', I wonder if any of the chip guys could program their chips to control the GP ground like the Super Duties, so that if the oil temp is more than, say, 150F, don't turn on the GPs at all. Hmm, puzzle puzzle.....
Hmm, this gets me thinkin', I wonder if any of the chip guys could program their chips to control the GP ground like the Super Duties, so that if the oil temp is more than, say, 150F, don't turn on the GPs at all. Hmm, puzzle puzzle.....
Postmaster
Joined: Sep 2007
Posts: 4,195
Likes: 6
From: Medford Oregon
Fleet Owner
Joined: Aug 2004
Posts: 20,418
Likes: 197
From: AZ
If I forget to flip the switch off after the normal cycle of the glow plugs and if my motor (oil) is warm on the next start my GP will not run.
Arctic, mine is not set up control the time they are on. If my switch is on, the GP's run normal. If its off, they don't run at all.
Like Madpogue said, I try to flip the switch back on after the last run of the day so the next day they will run normal. I have forgotten to do this and it won't start the next day. If my wife takes the truck, I leave it on for obvious reasons, LOL.
Arctic, mine is not set up control the time they are on. If my switch is on, the GP's run normal. If its off, they don't run at all.
Like Madpogue said, I try to flip the switch back on after the last run of the day so the next day they will run normal. I have forgotten to do this and it won't start the next day. If my wife takes the truck, I leave it on for obvious reasons, LOL.
FOREIGN GURU
Joined: Jul 2006
Posts: 7,655
Likes: 7
From: Celaya, Gto. MX
I wouldn't rule out the possibility. This is why, if you're gonna do a workaround, probably the most useful one would be a regular SPST toggle switch (not a momentary) in _series_ in the wire going from the relay to the PCM. Leave it in the ON position, the plugs cycle as they would normally, the PCM will turn them off long before they overheat or carbon up or whatever. But for those runaround-town trips, when you're starting an already warm engine, you can flip the switch OFF. Flip it back ON when you get to your final destination, so that next time, when you start cold, it'll cycle as usual.
Hmm, this gets me thinkin', I wonder if any of the chip guys could program their chips to control the GP ground like the Super Duties, so that if the oil temp is more than, say, 150F, don't turn on the GPs at all. Hmm, puzzle puzzle.....
Hmm, this gets me thinkin', I wonder if any of the chip guys could program their chips to control the GP ground like the Super Duties, so that if the oil temp is more than, say, 150F, don't turn on the GPs at all. Hmm, puzzle puzzle.....
If I forget to flip the switch off after the normal cycle of the glow plugs and if my motor (oil) is warm on the next start my GP will not run.
Arctic, mine is not set up control the time they are on. If my switch is on, the GP's run normal. If its off, they don't run at all.
Like Madpogue said, I try to flip the switch back on after the last run of the day so the next day they will run normal. I have forgotten to do this and it won't start the next day. If my wife takes the truck, I leave it on for obvious reasons, LOL.
Arctic, mine is not set up control the time they are on. If my switch is on, the GP's run normal. If its off, they don't run at all.
Like Madpogue said, I try to flip the switch back on after the last run of the day so the next day they will run normal. I have forgotten to do this and it won't start the next day. If my wife takes the truck, I leave it on for obvious reasons, LOL.
But again my question for madpogue and Hussler, is there any REAL problem in the GPs or engine IF you NEVER flip the switch ON?
Lead Driver
Joined: Oct 2003
Posts: 8,476
Likes: 37
From: Madison, WI
If the engine is just warm enough to start, but no hotter, it'll be a little less efficient (and will pollute a bit more) without the added heat from the GPs. That's the reason the PCM keeps them on after start.
FOREIGN GURU
Joined: Jul 2006
Posts: 7,655
Likes: 7
From: Celaya, Gto. MX
Lead Driver
Joined: Oct 2003
Posts: 8,476
Likes: 37
From: Madison, WI
Hm, that I can't say for sure. But I can't imagine anyplace where it NEVER gets cold enough that you'd want to run the GPs at least once in a while.
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FOREIGN GURU
Joined: Jul 2006
Posts: 7,655
Likes: 7
From: Celaya, Gto. MX
IDK.
Laughing Gas
Joined: Feb 2014
Posts: 774
Likes: 25
From: Reno, Nevada
I know this thread is several years old but I just installed a manual GPR bypass momentary contract switch and thought I'd add my two cents to the discussion. My switch is completely manual and the PCM is no longer in the circuit except to light up the Wait to Start light.
On cold mornings I use the same start procedure as my excavator, which has a manual glow plug switch. First I crank the engine over a couple of revolutions with no glow plugs on to get some fuel oil in the combustion chambers. Then, without cranking the starter, I hold the GPR switch on while the WTS light it is lit, or maybe a little longer, depending on how cold it is.
Then I crank the starter with the glow plugs off. I think this lets the starter crank a bit faster without having to feed the glow plugs at the same time, and the glow plugs are still very hot. If it's idling rough when it starts I hold the glow plug switch on for a few moments 'til it smooths out.
Seems to be working very well. It fired up immediately yesterday morning with no block heater at 17 F. I know that isn't very cold for some of you guys.
Bob
On cold mornings I use the same start procedure as my excavator, which has a manual glow plug switch. First I crank the engine over a couple of revolutions with no glow plugs on to get some fuel oil in the combustion chambers. Then, without cranking the starter, I hold the GPR switch on while the WTS light it is lit, or maybe a little longer, depending on how cold it is.
Then I crank the starter with the glow plugs off. I think this lets the starter crank a bit faster without having to feed the glow plugs at the same time, and the glow plugs are still very hot. If it's idling rough when it starts I hold the glow plug switch on for a few moments 'til it smooths out.
Seems to be working very well. It fired up immediately yesterday morning with no block heater at 17 F. I know that isn't very cold for some of you guys.
Bob
Cargo Master
Joined: Jul 2006
Posts: 2,756
Likes: 38
From: Nampa, ID
Interesting older thread. I like the comments about the GPs and GPR's operating cycle. Gives me something to think about for the next GPR replacement. I'm still running the OEM replacement, but have considered the Stancor as a replacement option. If (when) a replacement is needed, I'll have to decide if I want to include the switch, too.
Fleet Owner
Joined: May 2009
Posts: 21,437
Likes: 76
From: Gilbert, PA
I wanted to add to this.
A problem that I see happening with not having the glow plugs cycle is..
CARBON BUILDUP.
then when they fail, the carbon buildup will not allow the removal of the glow plug.
just something to think about
A problem that I see happening with not having the glow plugs cycle is..
CARBON BUILDUP.
then when they fail, the carbon buildup will not allow the removal of the glow plug.
just something to think about
Laughing Gas
Joined: Feb 2014
Posts: 774
Likes: 25
From: Reno, Nevada
There are a lot of guys running the manual GPR switch and, although it doesn't prove anything, I've yet to hear of an actual problem.
But yes, there probably is a certain amount of risk involved.
Bob
