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Generator Pre-heat time

I have noticed that the cold temps outside directly effect the generator starting.  At 40 degrees I have been holding in the preheat switch for 15-20 seconds and the generator cranks but immediately shuts off, I have to repeat this at least three times to get it to stay running.  When I held the preheat switch in for 40-60 seconds the generator cranked first time and continued to run.  All filters have been changed and all fuel lines look good-no cracks.  The longer you hold the preheat switch in the brighter the green light at the switch becomes.  What is the "normal" time the preheat should be held in? 
Terry
Terry and Cheryl Brown
1997 U295 36'
Build #5066
2006 Jeep TJ Rubicon
1993 BMW R100 GSPD

Re: Generator Pre-heat time

Reply #1 –
How cold is it?  I have no issues down to the teens with the preheat as being as long as the regular time.  I have started it as low as 9 degrees that way too.  It is a bit rough to start but settles right down. I have the 12.5 Powertech.
2025 Wanderbox Outpost 32 on F600 Expedition Motorhome
2015 Born Free Royal Splendor on Ford 550 nonslide version  for sale
Former Coaches  covering. 360,000 miles
1999 34 U270
2000 36 U320
2001 42' double slide U320
2018 Jeep Rubicon

Re: Generator Pre-heat time

Reply #2 –
Elevation and temperature determine how long you should glow. At around 8000 feet, the air is 25% less dense so you have a lot less heat generated by compression so you need to make up for it with glowing longer. Other factors like how much cranking voltage is available, valves adjustment, weight of the oil, etc. Also, check your glow plugs as one bad one will really effect starting.

At about 8000 feet in Yellowstone and the temp in the teens, I glowed for over a minute and had to repeat it once. Outside temperature effects starting on all diesels as they are all compression ignition engines.

Pierce 
Pierce and Gaylie Stewart
'93 U300/36 WTBI
Detroit 6V-92TA Jake
1140 watts on the roof
SBFD (ret)

Re: Generator Pre-heat time

Reply #3 –
But does the generator know it is at altitude or how cold it is out.  I have never had mine run twice in Yellowstone or anywhere else.  I agree on what you said about less air and needed heat but I have not seen a longer wait time yet on any of my three coaches.
2025 Wanderbox Outpost 32 on F600 Expedition Motorhome
2015 Born Free Royal Splendor on Ford 550 nonslide version  for sale
Former Coaches  covering. 360,000 miles
1999 34 U270
2000 36 U320
2001 42' double slide U320
2018 Jeep Rubicon

Re: Generator Pre-heat time

Reply #4 –
Quote from: CAPEHORN31 –
I have noticed that the cold temps outside directly effect the generator starting.  At 40 degrees I have been holding in the preheat switch for 15-20 seconds and the generator cranks but immediately shuts off, I have to repeat this at least three times to get it to stay running.  When I held the preheat switch in for 40-60 seconds the generator cranked first time and continued to run.  All filters have been changed and all fuel lines look good-no cracks.  The longer you hold the preheat switch in the brighter the green light at the switch becomes.  What is the "normal" time the preheat should be held in? 
Terry
In cold weather I hold the preheat switch "on" for 5-10 seconds after it starts.
Good luck,
Rick
Rick

Re: Generator Pre-heat time

Reply #5 –
The preheat switch also runs the electric fuel pump and I do the same as Rick. Keep holding it on until the gennie runs normally.
1994 U280, Build 4490
Deming, NM.

Re: Generator Pre-heat time

Reply #6 –
I've found that the temp and altitude doesn't seem to make a difference. I glow, start and hold the start switch about two seconds and all is right with the world
Larry
1996 U295 36'
Build # 4805
Actually we sold it but just like to lurk

Re: Generator Pre-heat time

Reply #7 –
Quote from: Rick –
In cold weather I hold the preheat switch "on" for 5-10 seconds after it starts.
Good luck,
Rick

Thanks for the advice.  When I held the preheat in for 5 seconds after the generator started everything worked great.  The generator cranked on the first try and kept running.  It was 48 degrees outside so I guess the generator doesn't care how cold it is. 
Terry
Terry and Cheryl Brown
1997 U295 36'
Build #5066
2006 Jeep TJ Rubicon
1993 BMW R100 GSPD

Re: Generator Pre-heat time

Reply #8 –
Should there be an actual seperate toggle for glow plug heating, mine must be automatic due to the fact that I don't have one. Might be nice though. jc 99 320 Isuzu
JC
1999 U320

Re: Generator Pre-heat time

Reply #9 –
Quote from: hotonthetrail –
Should there be an actual seperate toggle for glow plug heating, mine must be automatic due to the fact that I don't have one. Might be nice though. jc 99 320 Isuzu

Yes, earlier models have a separate switch. You can hold it down as long as you want.

Pierce
Pierce and Gaylie Stewart
'93 U300/36 WTBI
Detroit 6V-92TA Jake
1140 watts on the roof
SBFD (ret)

Re: Generator Pre-heat time

Reply #10 –
Quote from: hotonthetrail –
Should there be an actual seperate toggle for glow plug heating, mine must be automatic due to the fact that I don't have one. Might be nice though. jc 99 320 Isuzu
Quote from: hotonthetrail –
Should there be an actual seperate toggle for glow plug heating, mine must be automatic due to the fact that I don't have one. Might be nice though. jc 99 320 Isuzu

Powertec 10KW with Kubota 4 cyl
dash controls


Rick

Re: Generator Pre-heat time

Reply #11 –
Quote from: Rick –
Powertec 10KW with Kubota 4 cyl
dash controls

That is exactly what mine looks like.  I now hold the preheat button in 5-10 seconds after the generator starts.  Of course I release the generator start button immediately after the generator starts.  So far the generator starts first time with no stumbling. If there is a problem starting the generator this way, somebody please let me know
Terry
Terry and Cheryl Brown
1997 U295 36'
Build #5066
2006 Jeep TJ Rubicon
1993 BMW R100 GSPD

Re: Generator Pre-heat time

Reply #12 –
We live at 8,000 ft in northern New Mexico.  Our 96 U270 is parked near the house.  Unless we leave in November, we can not drive the motorhome up and down the mountain road to our house.

During my monthly engine runs and checks of systems, I too hold the generator switch 5 to 10 seconds beyond the intial cylinder firings during start.  This is after two cycles of cylinder warming with the glow plugs: 20 seconds on, 20 off, 15 on, then start.  These scheme works for me.

I scoff at those owners who do not apprciate the effects of altitude and temperature.  As normal in any year, our nights have been below 0 more than above, so far this.

andy
Carolyn and Lewis (Andy1) Anderson
1996 U270 36'

Re: Generator Pre-heat time

Reply #13 –
Quote from: CAPEHORN31 –
That is exactly what mine looks like.  I now hold the preheat button in 5-10 seconds after the generator starts.  Of course I release the generator start button immediately after the generator starts.  So far the generator starts first time with no stumbling. If there is a problem starting the generator this way, somebody please let me know
Terry
Terry,
    Actually I do this on every start now and have been for the past few years. I have a Kubota tractor with the same engine and also hold the glow plugs on after every start (doing it at least 10 years). For a definitive answer from Kubota, give them a call, but it works in my experience and has not caused any issues, knocking on wood.
Rick
Rick

Re: Generator Pre-heat time

Reply #14 –
Depending on the make and model, many diesel automatic controllers will keep the glow plugs on for up to 90 seconds after the engine starts so holding the button down in cold weather (or any weather) won't do any harm.

In order to pass federal emission standards for diesel automobiles, the startup test bag can't have a high level particulates so they try to make the startup process as clean as possible. Generators don't have to pass the same emission standards as cars.

Pierce
Pierce and Gaylie Stewart
'93 U300/36 WTBI
Detroit 6V-92TA Jake
1140 watts on the roof
SBFD (ret)

Re: Generator Pre-heat time

Reply #15 –
I do not disagree about temps or altitude but on my FT there is only a start button and a auto button.  ON my Born Free there is a preheat button you hold as long as you want. 
2025 Wanderbox Outpost 32 on F600 Expedition Motorhome
2015 Born Free Royal Splendor on Ford 550 nonslide version  for sale
Former Coaches  covering. 360,000 miles
1999 34 U270
2000 36 U320
2001 42' double slide U320
2018 Jeep Rubicon

Re: Generator Pre-heat time

Reply #16 –
Quote from: John S –
I do not disagree about temps or altitude but on my FT there is only a start button and a auto button.  ON my Born Free there is a preheat button you hold as long as you want.
                    John mine is the same, one start one auto. What I "assume" is that as long as you hold the start button in at the on position it activates the glow plugs and starts a couple of seconds after release.

                                  Dean
Dean & Deirdre

2012 Arctic Fox 22GQ
Was 2003 U270