Onan 6.5NH Attempting to Bring it Back

[EyezOpen]

This generator has been sitting for about 8 yrs in a rv housing, i will say it looks in very good condition. With that being said there are issue's first starting with myself, getting older and i am starting to lose my enthusiam for job's of this nature. So i will try to post here looking for short cut's...perhaps insight to what i am truly facing.

Issue's it will not crank period.

1. Soaking the cylinder's in SeaFoam& Mystery oil for a week now. New oil&filter.
2. New battery 750 cranking amp fully charged, solenoid one click's only,so far i have used the rv wiring to start all connection's cleaned no luck, then a direct battery to solenoid connection no luck. Then i applied a charger with a starting funtion about 50 amps in start mode...no luck no heat in the solenoid nothing no light buzz heard from any kind of amperage draw and never a large arc occuring from
3.The fuel pump is no longer functional simply just a loud banging noise, it has been unhooked the entire time any starting attempt's.
4. Im quite convinced it a solenoind yet solenoid's dont go bad from just sitting there...i think.

With all that being said ive taken the time to look at some manuals, it seem's there is the matter of the brushes, valves etc etc. With all this being said i know it has to come out of the dog house for a complete service so be it.

The thing that i need is to get it to turn over or crank at least, it has bothered me i never once experienced a arc of any substance in searching for a ground. Is there any type of circut in this system that will overide the starting circut...aka fuel sensor oil sensor load sensor etc etc. Along with that i cannot see a way to maually crank the engine/generator by hand without pulling it out.

Ok i get im lazy...any insight's here...Ive never ran into a situation where i could not get a engine to at least make a grunt...speaking of that is there a way to short the starter solenoid if that's even possible input or thought's.

Model No. 6.5NH 3CR/16004P
Serial No. J823633181

 

[MBB]

Re: Onan 6.5NH Attempting to bring it back

Welcome to the Stak. You could try jumping from one side of the solenoid to the other with a couple screwdrivers or wrenches. You could use a piece of heavy gauge wire as well. Im taking it that you were supplying power to the battery side of the solenoid. Otherwise put a wrench on the flywheel and make sure the motor is not locked up. Though I would expect a large draw creating a large spark if it were seized. Good luck.

 

[YellowLister]

Re: Onan 6.5NH Attempting to bring it back

Pull the generator cover off the very back of the gen end, should be 2 big flathead screws, and see if you can turn the fan bolt clockwise, with the spark plugs out.

If not it is locked up and you need to pull the cylinder heads and see how bad it is.

 

[turtmaster]

Re: Onan 6.5NH Attempting to bring it back

Double check to make sure that the starter solenoid is the correct part number/correct wiring configuration, it looks like a standard Ford type starter solenoid, but it is wired differently internally, depending on model, also check to make sure that the engine is not hydrolocked, also check to make sure that the generator end brushes, are "free moving" in their holders, also jumper cables will not work, there is too much resistance in the clamp connections, the battery cable connections pretty much need to be "bolted/soldered" connection, if all of the above are fine, maybe try a different battery?

 

[trukinbear]

Re: Onan 6.5NH Attempting to bring it back

A bad solenoid could have been the reason it's sat there for so many years - I wouldn't rule anything out just because it doesn't seem like just sitting there would cause it to fail. Pre-failed perhaps?

 

[EyezOpen]

Re: Onan 6.5NH Attempting to bring it back

My first thought was to jump the solenoid, yet it is not wired like a for ford so i nixed that ideal. A ford starter clearly has a negative and positve side this has a postive side only....that is a clear positve side that is....I cant imagine the small wiring on any of the other lug's being any type of starter ground....Odd looking setup. Im sure well maybe sure it can be shorted to force a turn over...just how to do that is the question.

---------- Post added at 05:33:08 PM ---------- Previous post was at 05:26:18 PM ----------

Pull the generator cover off the very back of the gen end, should be 2 big flathead screws, and see if you can turn the fan bolt clockwise, with the spark plugs out.

If not it is locked up and you need to pull the cylinder heads and see how bad it is.

Ok the back of the unit, that can be done i beleive, very tight quarters.

 

[YellowLister]

Re: Onan 6.5NH Attempting to bring it back

These are exciter cranked.. the gen is the starter. If you bypass the solenoid and go directly to the + cable off the solenoid going to the gen end inside the control box and have the ground bolted to the bottom bolt on the generator end and it wont turn over good chance it is locked up, or something seriously bad happened in the generator end.

 

[Jim McIntyre]

Re: Onan 6.5NH Attempting to bring it back

These are indeed started by the generator itself. A consequence is they draw a lot of current off your starting battery (WAY more than you might expect for a 'small' engine), and the condition of the brushes matters. A lot.

So you need a BFB (big *!@# battery) and make sure the brushes move freely in their holders.

---------- Post added at 08:04:21 PM ---------- Previous post was at 08:03:20 PM ----------

...also check to make sure that the generator end brushes, are "free moving" in their holders, also jumper cables will not work, there is too much resistance in the clamp connections, the battery cable connections pretty much need to be "bolted/soldered" connection, if all of the above are fine, maybe try a different battery...

^^YES!!!

 

[EyezOpen]

Re: Onan 6.5NH Attempting to bring it back

These are exciter cranked.. the gen is the starter. If you bypass the solenoid and go directly to the + cable off the solenoid going to the gen end inside the control box and have the ground bolted to the bottom bolt on the generator end and it wont turn over good chance it is locked up, or something seriously bad happened in the generator end.

Seriously wrong is my concern, however i did not bypass the solenoid. I merely dismounted the power cable from the solenoid and went directly from the battery to the soleniod...Are you saying one can send power from the battery directly to the aramture what ever starter...that seems a bit to extreme for me anyways..

Power went from the battery to the solenoid, then using the power switch i triggered the solenoid only a small click as a result. Multiple switching did not result in any heat build in the solenoid nor and pull of amperage. One would think if power did go to the amarture starter what ever its called there would be some draw...buzzz...slight oder...something.

---------- Post added at 07:39:07 PM ---------- Previous post was at 07:29:33 PM ----------

The battery is new, known to function. It was also assited by a charger with a start option. That option delivers 40 amps for 90 second's but again absolutely no reaction no draw down buzz....no faint oder and the charger lights did not dimm what so ever. I did paly with the ground a bit, actually took the ground off the generator and it reacted in the very same manner just a click...I assume the generator is grounded by the frame bolts that hold in place?

---------- Post added at 07:46:44 PM ---------- Previous post was at 07:39:07 PM ----------

These are indeed started by the generator itself. A consequence is they draw a lot of current off your starting battery (WAY more than you might expect for a 'small' engine), and the condition of the brushes matters. A lot.

So you need a BFB (big *!@# battery) and make sure the brushes move freely in their holders.

---------- Post added at 08:04:21 PM ---------- Previous post was at 08:03:20 PM ----------



Ive thought about for a bit, this generator was serviced just prior to it being put to bed so to speak. With that being said it was always started with two large deep cell 12volt battery's hooked up together. That much power????

 

[YellowLister]

Re: Onan 6.5NH Attempting to bring it back

I would make sure it turns over easy first.. you can directly connect the battery to it.. but for just a quick 2 seconds just incase it is locked up you don't want to melt battery cables or wires in the gen end.

No point in melting wires if there is just a little rust in the cylinder that can be easily cleaned then damaging the gen end and having to fix that too..

If you do get it to turn over easy.. hook the battery up and see if 12v is getting to the other side of the solenoid with a multimeter and go from there.. could just have a bad, or wrong solenoid or the starter switch could have bad corroded contacts

 

[lokay5]

Re: Onan 6.5NH Attempting to bring it back

Connect jumper cables to a large, fully-charged 12V automotive/truck battery.
Connect the positive cable to the large solenoid terminal which is connected to the cable that enters the generator.

Touch/connect the other jumper to the generator at a good, clean ground on the generator itself.
The engine should now crank.

 

[EyezOpen]

Re: Onan 6.5NH Attempting to bring it back

Connect jumper cables to a large, fully-charged 12V automotive/truck battery.
Connect the positive cable to the large solenoid terminal which is connected to the cable that enters the generator.

Touch/connect the other jumper to the generator at a good, clean ground on the generator itself.
The engine should now crank.

Ive done as much already, I ran the battery direct to the to the power side of the solenid and grounded the the battery to the Gen and the frame of the rv. Unless i am reading this wrong that does not short the solenoid or by pass it. Hooked up in that fashion one just replaces the RV's wiring which is a good thing to do. However i still had to use the ignition switch to engage the circut resulting again in a mere click.

It has been many yrs since ive worked on something of this nature, the frustration of something so simple is over, its apparent something is interupting the starting circut and not knowing how this solenoid is wired makes shorting it and finding the problem not simple. So i guess throwing parts at it is the start...there only $20 but i hate spare part's collection's over the yrs it beomes annoying. I thank all those who have provided insight and there thought's.

 

[nothingbutdarts]

Re: Onan 6.5NH Attempting to bring it back

What Loyal is trying to say is to bypass the start solenoid completely. The solenoid has two bigger lugs 5/16" thread, one side will come from the RV battery, the opposite side will be a thick gauge wire going to the armature brushes, you want to hook the + battery cable to this thick wire and the - battery cable to a good clean ground on the generator frame. IF, this does not make the generator start to crank over, then as suggested pull the brush band off the back end of the generator, make sure all spade terminals are connected and that all brushes are free in their holders. While you are in there you might as well make sure the engine will turn over by hand, I like to attempt to gently push on two fan blades of the cooling fan, so as not to bend the fan blades.

 

[len k]

Re: Onan 6.5NH Attempting to bring it back

Here's an easier basic test. Take any 12V test light and put it between ground and FAT stud on starter side of solenoid, then try to crank engine. See if light comes anywhere close to bright.

If not then move light to FAT stud on bat side of solenoid and repeat.

 

[EyezOpen]

Re: Onan 6.5NH Attempting to bring it back

Yes i just went out and doubled checked the solenoid, and found a cable heavy enough to transfer that much power. It was literally buried in gang of wiring, i have some pics but my old photobucket account was hijacked, they actually want $300 to reconnect. I will go out and make the jump thank you very much.

---------- Post added at 01:09:22 PM ---------- Previous post was at 01:08:01 PM ----------

Here's an easier basic test. Take any 12V test light and put it between ground and FAT stud on starter side of solenoid, then try to crank engine. See if light comes anywhere close to bright.

If not then move light to FAT stud on bat side of solenoid and repeat.

Ok will do,

 

[lokay5]

Re: Onan 6.5NH Attempting to bring it back

Ive done as much already, I ran the battery direct to the to the power side of the solenid and grounded the the battery to the Gen and the frame of the rv. Unless i am reading this wrong that does not short the solenoid or by pass it. Hooked up in that fashion one just replaces the RV's wiring which is a good thing to do. However i still had to use the ignition switch to engage the circut resulting again in a mere click.

It has been many yrs since ive worked on something of this nature, the frustration of something so simple is over, its apparent something is interupting the starting circut and not knowing how this solenoid is wired makes shorting it and finding the problem not simple. So i guess throwing parts at it is the start...there only $20 but i hate spare part's collection's over the yrs it beomes annoying. I thank all those who have provided insight and there thought's.

You did indeed "read it wrong"
Again:
Connect a set of heavy-duty jumper cables to a large fully charged 12V automotive/truck battery.
Connect the positive (+) cable to THE LARGE SOLENOID TERMINAL THAT HAS A LARGE CABLE THAT ENTERS THE GENERATOR.
Touch the generator with the negative (-) cable to a good clean ground on the generator.
This effectively eliminates the solenoid from the circuit.
If all is well with the armature and brushes and the engine is not seized, it will turn over.
Get an arc and it doesn't turn over the engine/generator is probably seized.

 

[EyezOpen]

Re: Onan 6.5NH Attempting to bring it back

Pics finally there is a heavy cable underneath that rat's nest, the second pic shows the cable... kinda.

Ok never mind it seems I can't get the upload to size correctly, they say things come in 3's what is next coming to mind

 

[I like oldstuff]

Re: Onan 6.5NH Attempting to bring it back

Waved the magic wand over them for you.

 

[lokay5]

Re: Onan 6.5NH Attempting to bring it back

Waved the magic wand over them for you.

Good work!


The terminal on the LEFT is where to connect the positive jumper cable.

 

[Kevin K]

I have attached a copy of your wiring diagram. As you can see, the starter solenoid uses an isolated coil, unlike the Ford solenoids it resembles. I would attempt to turn the engine over by hand before trying to crank it, just to be sure nothing is seized. If that goes OK, remove the generator band and check all the brushes to be sure they move freely in their holders, and no mice have gotten in and chewed on the wiring.