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Foretravel Motorhome Forums => Foretravel Tech Talk => Topic started by: CAPEHORN31 on January 19, 2013, 04:32:43 pm

Title: Generator Pre-heat time
Post by: CAPEHORN31 on January 19, 2013, 04:32:43 pm
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
Title: Re: Generator Pre-heat time
Post by: John S on January 19, 2013, 04:57:56 pm
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.
Title: Re: Generator Pre-heat time
Post by: Pierce & Gaylie Stewart on January 19, 2013, 05:19:54 pm
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 
Title: Re: Generator Pre-heat time
Post by: John S on January 19, 2013, 05:33:44 pm
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.
Title: Re: Generator Pre-heat time
Post by: Rick on January 20, 2013, 12:31:58 pm
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
Title: Re: Generator Pre-heat time
Post by: Twig on January 20, 2013, 12:38:59 pm
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.
Title: Re: Generator Pre-heat time
Post by: lgshoup on January 20, 2013, 01:35:12 pm
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
Title: Re: Generator Pre-heat time
Post by: CAPEHORN31 on January 21, 2013, 09:48:20 am
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
Title: Re: Generator Pre-heat time
Post by: hotonthetrail on January 21, 2013, 10:04:28 am
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
Title: Re: Generator Pre-heat time
Post by: Pierce & Gaylie Stewart on January 21, 2013, 10:22:22 am
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
Title: Re: Generator Pre-heat time
Post by: Rick on January 21, 2013, 10:25:16 am
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
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


Title: Re: Generator Pre-heat time
Post by: CAPEHORN31 on January 21, 2013, 11:47:45 am
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
Title: Re: Generator Pre-heat time
Post by: Lewis Anderson on January 21, 2013, 12:33:00 pm
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
Title: Re: Generator Pre-heat time
Post by: Rick on January 21, 2013, 12:46:38 pm
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
Title: Re: Generator Pre-heat time
Post by: Pierce & Gaylie Stewart on January 21, 2013, 01:24:01 pm
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
Title: Re: Generator Pre-heat time
Post by: John S on January 21, 2013, 02:58:07 pm
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. 
Title: Re: Generator Pre-heat time
Post by: Dean & Dee on January 21, 2013, 03:16:57 pm
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