Where is the Onan R1 Resistor?

[swebster]

OK..I have a new Onan R1 resistor for my 6.5 but cannot find it. Before I take everything apart I wondered if anyone knew where this was located? Thanks

[George]

Hello Steve,
Forgive me, But I don't understand your question?
did you purchase a resistor because you had a bad one ??
it's unclear (to me anyway) how we can help you.
Later ol' George

[swebster]

George,
Sorry, you're right. I guess I feel like the entire forum is right beside me when I'm working on the AS and already knows what I'm talking about

Here's the background:

When we got the MH (86 345) the genset cranked but would not start.
I replaced the points, plugs, removed the manifold/carb cleaned the jets, changed the oil and adjusted the choke. Presto...it ran...for a while. After about an hour it would blow the ignition fuse. I put in a slow blow and it would last a little longer.

Finally it’s now to the point where it will start and run when holding the START switch down but will stop as soon as I release the switch.

The troubleshooting section in the Onan manual points to one of three things for this behavior; low oil, faulty oil-pressure switch or a faulty R1 resistor.

I have plenty of oil (just changed) and purchased both a replacement oil pressure switch and new R1 resistor. On the advice of the Cummins/Onan expert at my friendly neighborhood RV dealer: "It's almost always the resistor". So, I'm simply trying to find it so I can perform the checks in the manual and possibly replace it with the new one.

I can’t see it near the relay or the in main box so I’m guessing where it is located.

[George]

Steve,
I can't help you on that, as My little Onan is pre electronic/oil pressure switch,etc.But if it were me, I'd be looking in the circuit/control box on the Generator as that would be where I think it should be. as it controls the gen. workings.

Yep lots of us have helped others, in turn we learn. I was amazed at this internet thing, kinda reinstilled my faith in mankind/people.
A person one never met nor ever will 'round the world will offer advice/help,just to be "neighborly"
sometimes, I think more so, as if one would be slightly incorrect or offering an openion, they would not have to feel imbarassed as they would in person.
sorry, enough rambling for an ol' Boy
Geo.

[thenewkid64]

Steve,

In my onan manual it shows the R1 resistor in the wire wad under the cover by the crank and run relays. The picture has it as a small can with a wire coming off each end. This wiring drawing includes references to the oil pressure sense wire, so I would think it should get you close.

[George]

Steve,
on a lot of old Ign. systems (pre electronic) they had a dropping resistor to lower the voltage to the braker points from 12V. to about 6V. (to give better point life)
BUT when the engine was starting, they jumpered the res. to allow the full 12V. to give a hotter spark as well as kinda make up for the voltage loss caused by the starter drain. they will be in the ign. primary circuit.
they were usually a porcilin (sp.) res. about 3/4x3/4 x 3" or so.
they liked to put them in the air flow to keep em' cool ( used to be on the firewall in autos.
Luck, Geo.

[swebster]

Brett, its definately not in the box so I'll look under it next. Thanks for the PM on this!

George, I appreciate your comments about the internet/forum. I make my living in technology so I'm used to it, but I've said before on the forum and expecially to friends and family that I can't imagine owning a classic AS without this forum. The sage advice (both direct and indirect) from all over the world makes resolving issues like this, for DIY guys like me, possible without taking it to the dealership.

[74Argosy24MH]

Is it a power resistor or a little 1/2 watt?

John

[wb13798]

just talked to my onan tech. he says check for ac while you hold the start switch on. if you are genereating ac . at the coach ac plug then it is possibly the oil pressure switch.or you dont have oil pressure. if it is not generating ac it could be the diode pack rotor stator or brushes,it has to generate ac to stay running. if you need to check the stator rotor or brushes take it to onan
as it could be a control board and they cost money.lol]
al

[swebster]

Here is a pic of the resistor in question (its about 2"" x 1/2" and has a hole in the middle. Al..I didn't have a chance to check AC output while running today. I'll try that tomorrow.

If I can read a schematic it looks like the resistor is under the control box (thanks Brett). It's listed as a 352-0161 - Resistor - 100 Ohm, 5 Watt with Start-Disconnect.

Looks like I'll be getting more familiar with my Onan soon. Thanks to all for the suggestions. I'll keep you posted.

[swebster]

I finally received the right resistor from Onan and installed it. The one coming out was clearly blown (big burn on the side). Put the new one in and I still have the same issue....generator starts and runs but then shuts off when I release the start switch. Onan manual says its either: low oil level (not), the R1 Resistor (replaced), or a faulty oil pressure switch (maybe). Also a mechanic told me the relay can go bad and kill the resistor.

Any ideas would be appreciated. Because there was evidence of failure in the ignition cicuit (burned resistor and previously blowing slow blow fuses every three hours) I suspect the ignition side more than the oil pressure side.

I¡¦m frustrated after waiting three weeks for this part that I¡¦m still without a working generator. Two big trips in the coming two weeks so I was hoping to have this working by now¡K.

On the upside¡Kmy two front Bilsteins arrived today ƒº

[PeterH-350LE]

Originally posted by swebster@myrvadvanta
........ ļ.........

How did you do that character?

Besides the 3 probable causes, you should check the 'Run ignition Relay, which is marked K3 in my manual. Voltage should be 12V on both sides.

[swebster]

Peter...the character must have copied from Word XP...I did a smiley in word and thats what came out when I pasted it in the editor.

I'll check the relay also. This is no fun!

[jaiman]

Thanks for linking this post sounds like my problem. I will check it out today.

[Tinsel Loaf]

Short out the low oil switch and run the gen so you can eleminate that as a problem.

[Mike Lewis]

swebster-----here's a thought that will only take a minute to check. As george mentioned the point type ignition uses a resister to lower voltage to the points to keep them from burning up. While the engine is being cranked 12 volts is applied directly to the points and ignition system providing a higher voltage to the coil and thus higher voltage to the spark plug during cranking for starting purposes . When the engine starts and the start switch is released the ignition current is directed through a resistance unit to reduce the voltage and extend point life. That said it is possable to have a fouled or partially fouled spark plug that will fire when in the crank position and has the higher voltage applied then when the switch is released and the lower voltage is applied there may not be sufficient voltage to fire the plug. Just a thought but sometimes the simplest things are over looked.-----Pieman

[Mike Lewis]

swebster----as to "shorting out the oil presure switch". To properly by-pass that switch you must determine if it is a normally open or normally closed switch. As rule of thumb a switch with a single wire is normally closed and one with 2 wires normally open. I both cases these switches a generally by passed during cranking and then become functional when the ignition in in the run position thus it would exhibit the condition you describe if it is defective. To test a normally closed switch <one wire> just unplug the the single wire from the switch and try it. To by pass a normally open switch < two wire> unplug the switch and jumper across the wire end connector and try it. Sometimes locating the switch is the hardest part of this job.
Pieman

[swebster]

Pieman,
Thanks....this was an old post. It turned out to be my Oil Pressure switch. Replaced it and the GenSet has been purring for almost two years now.

Also, noticed at the same time some chaffed wires in the control box which I'm sure caused the original R1 burnout.

[wiytboi]

ok the resistor in mine is screwed to the side wall just behind the start switch next thing is im searching for a resistor part# 304-0735. any one got a clue where i could get my hands on one.?

[George]

I see you are new, so
you might want to check the date of the post you are replying to as
alot of things happen in FIFTEEN YEARS!