Cummins Onan RV QG 7000 garbage

The friendliest place on the web for anyone with an RV or an interest in RVing!
If you have answers, please help by responding to the unanswered posts.

Marchos77

Active member
Joined
Dec 5, 2018
Posts
32
Location
Chuluota, FL
So we traveled to Washington DC from Orlando, FL through Roanoke Island, NC and Williamsburg, VA. On our way the generator stopped working somewhere between Williamsburg and DC. While at the Cherry Hill Park campsite in MD I was able to take apart the generator while in the RV and found that wire loom around some wires near the control board was melted. I assumed that the control board heated up so hot that it melted the loom but the casing wasn't damaged on the module or the plastic box around the module. Just the wires that ran passed the control board box.  I ordered the control module from Flight Systems which were gracious to ship the board on Friday for Saturday deliver. replaced the board Saturday when I got it and still the Generator doesn't want to start. Same issue, it will prime but will not start. I was able to get the casing on the generator high enough to reach the area of the starter and was able to take video of the area all around the generator.  Nothing stood out as damaged or overheated.  I was able to check the voltage on the Solenoid and had power.  Hit the start button and saw power going to the starter but nothing.  Thanks to a neighbor camper I was able to get the starter out of the generator.  Any tagging on the starter was melted and it looks as if the internal components of the starter melted as well. What crap.  So I am out a control board which I do believe is damaged as well as the starter. Anyone heard of this? Is there a way I can turn the motor on the generator without replacing the starter? I would like to know that its not a seized motor and hopefully just the starter.  Oil looks fine and is at level.  This is the second generator this RV has had in its 9 years of existence. Are these generators just garbage with a 5 year lifespan? Is there another make of generator that is available other than Cummins?
 

Isaac-1

Well-known member
Joined
Dec 3, 2016
Posts
5,864
Location
SW Louisiana
If things are getting that hot, I have to wonder if it is an installation / ventilation problem
 

Gary RV_Wizard

Site Team
Joined
Feb 2, 2005
Posts
76,166
Location
West Palm Beach, FL
It's the ventilation in the generator compartment that is most likely lacking.  It is ironic that sometimes gensets overheat when the compartment door is left open. That's because the air my not flow to the right places.
 

Mark_K5LXP

Well-known member
Joined
Nov 17, 2018
Posts
2,451
Location
Albuquerque, NM
My guess is something happened besides hot air.  For starter components to overheat implies high currents, possibly due to to excessive cranking or something that failed in the starter or starter circuit causing excessive current to flow.  You can cite "junk" or "poor ventilation" but consider there are many thousands of these units that have been produced over decades that are in daily recreational and commercial use, and this type of failure isn't typical. 

Mark B.
Albuquerque, NM
 

thesameguy

Well-known member
Joined
Jun 6, 2014
Posts
589
Mark_K5LXP said:
My guess is something happened besides hot air.  For starter components to overheat implies high currents, possibly due to to excessive cranking or something that failed in the starter or starter circuit causing excessive current to flow.

Totally agree. Melted wiring isn't a result of "air hot." Even the cheapest of cheap insulation is rated to 221F. Hotter than "engine running + physical contact" hot.

Melted insulation is touching something extremely hot, like an exhaust or the melted conductors inside it. I too would suspect high currents, maybe the result of a bad ground. A starter with an unstable ground can wreak havoc. That might explain why it works for a few years and then stops... maybe either an insufficient ground resulting in slow, ongoing damage or an unstable ground that just one day doesn't work right anymore.
 

Marchos77

Active member
Joined
Dec 5, 2018
Posts
32
Location
Chuluota, FL
I definitely understand the maintenance part.  From the looks of the generator the plugs, air filter, fuel filter and oil was changed before I purchased the RV.  Maybe when I tried to start it I held the button down too long. Hard to believe I would have done that since I am conservative with how I handle my equipment. Its weird that the wire loom that covers the wire for the remote switch was melted between the case and the control module. the casing on the control module was fine which I expected to have some heat damage but there was none. Gonna order the starter and see if there is an issue with ventilation around the generator.
 

Utclmjmpr

Well-known member
Joined
Sep 14, 2009
Posts
5,620
Location
Cedar City, UT
Many times when equipment sets for long periods,, the grounding points get corroded.. Then when applying a load the system "looks" for a better ground from another path, and usually on a smaller wire gauge, that's went all the smoke escapes from the system.>>>Dan
 

thesameguy

Well-known member
Joined
Jun 6, 2014
Posts
589
Marchos77 said:
Its weird that the wire loom that covers the wire for the remote switch was melted between the case and the control module. the casing on the control module was fine which I expected to have some heat damage but there was none.

Plastics all have different characteristics... if the loom is PVC and the wire insulation is SGX, the wire could get hot enough to melt the loom while leaving the insulation intact. Not necessarily suggesting that's what happened, only illustrating that X degrees F from a single source will affect different components differently. As Dan mentioned, big amps looking for a return path could create this sort of havoc. I once put a wire on the wrong terminal and thought I'd wrecked a car... fortunately the smoke stayed in the wiring but I did spend an afternoon replacing a bunch of annoying corrugated wire loom which did not survive the incident. I would inspect all the thick wires thoroughly - make sure they look good, and that their start & end points are clean and free of corrosion. When I experienced my first generator failure it was because the lead to the starter was poorly crimped (like EVERYTHING in my darned RV) and the wires had frayed...
 
Top Bottom