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An Onan JB Performance Question


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  #201  
Old 09-13-2017, 03:07:17 PM
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Default Re: An Onan JB Performance Question

"As for the wiring it is genuine Onan wiring, I never changed the wire size to the coil. Thank you for the offer but I intend to stay genuine Onan parts best I can."
Leon, I am not a big advocate of modifying FACTORY wiring either, never was, BUT, there comes a time where because of age the factory wiring and switches don't carry the current to satisfy the starter requirements.
Here is a suggestion, build up a TEMPORARY, heavier wire and switch starter circuit, bypassing the factory wiring and switch. See if it works the same as the factory circuit or if the starter holds in, when warm, with the temporary circuit.
I respect your wanting to keep things "Stock and original" but this set you need in an outage and you and your wife's well being depend on it. Chris
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  #202  
Old 09-13-2017, 03:11:45 PM
len k len k is online now
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Default Re: An Onan JB Performance Question

Know you want to keep it genuine Onan parts, but think you said mouse pee'd in control box. So some of the original control box parts may no longer be in genuine Onan condition. Other issue is it's not new anymore...... Generic new parts are better than old intermittent genuine parts.
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  #203  
Old 09-13-2017, 03:12:41 PM
Leon N. Leon N. is offline
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Default Re: An Onan JB Performance Question

Motorhead I hear ya and understand your logic. You make good points. However, since I measured 11+ volts steady-state at the small terminal should that not be good enough to activate the hold-in coil?
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  #204  
Old 09-13-2017, 03:22:53 PM
len k len k is online now
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Default Re: An Onan JB Performance Question

One thing I learned working on cars is Don't Assume Anything, test it. Lot of odd ball stuff happens.

Put ice pick test light between bat negative and case of solenoid , crank engine, see if it lights. Solenoid case may be intermittently poorly grounded.

Last edited by len k; 09-13-2017 at 06:57:53 PM.
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  #205  
Old 09-13-2017, 04:13:08 PM
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Default Re: An Onan JB Performance Question

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Originally Posted by Leon N. View Post
Motorhead I hear ya and understand your logic. You make good points. However, since I measured 11+ volts steady-state at the small terminal should that not be good enough to activate the hold-in coil?
I agree that 11 volts should be okay..... That's why I suggested a temporary start circuit to see if the wiring is the issue. I can tell you from the VW days that we would check this and that and assume all SHOULD work with what was there from the factory...But sometimes we were wrong and that's why we would end up installing the hard start relay and no more problems.
The 1976 Honda 550cc four cylinder motorcycle I had only had about 7,000 original miles on it and I had issues with the starting circuit. I even bought a brand new from Honda, EXPENSIVE!, starter button assembly to try to fix the problem. It worked okay for about 6 months then no start issue came back.
I wired in a relay which took the current load off of the NEW switch and stock wiring and no more issues.
Leon, Have you tried to just hot wire the starter motor when it has the warm drop out condition? In other words, just run a jumper wire from the large battery post on the starter solenoid and touch it to the small contact on the starter solenoid, holding it there long enough to see if the starter stays engaged?
This little orange 1976 Honda 550F is what you need to run around on Leon! I'm 65 and ride a 2007 BMW R1200cc GS
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  #206  
Old 09-13-2017, 04:53:01 PM
Leon N. Leon N. is offline
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Default Re: An Onan JB Performance Question

Motörhead I use to have a motorcycle license in MA. When I was a teenager I re jilt a Whizzer motor bike. HAd to get a motorcycle license to drive it on the streets. That was about 1954 or so. I remember what a laugh as the local inspector watched me handle the bike. Went into the service and I do not know what happened tol the old bike. After that lost interest and decided not to pay $ to renew each year so that ended my motorcycle interests.

LenK how can your idea work since the solenoid she'll is grounded to the JB frame? But, I will try it.
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  #207  
Old 09-13-2017, 05:50:46 PM
MBB MBB is offline
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Default Re: An Onan JB Performance Question

Motorhead your bike is like new!! I was a Honda bike mechanic for about 8 years. Started assembling bikes and went on to be a mechanic. The shop I worked at sold Yamaha and Honda. I preferred Honda. My first was a Honda moped I found in the river and my buddy and I re-built it buying parts from the Honda dealer. They eventually asked us to work there after school assembling bikes. $5.00 for anything under 500cc and $6.50 for anything over 500cc. I then bought a CB160 and rode that to school before I had a license. Bought CB750 and bored that out to 1147cc and eventually seized it racing a dragster at the dragstrip. I quit and they called me back to setup the CBX. That was a great bike. Been many years since ive ridden a bike but I still keep up my license.

Sorry Leon just remembering some fun times.
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  #208  
Old 09-13-2017, 07:01:55 PM
len k len k is online now
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Default Re: An Onan JB Performance Question

Leon ...... I would EXPECT solenoid shell to be grounded. But until you TEST , your ASSUMING.

On cars I've learned the hard way not to do that.

I've tracked down lights on a large box truck not working right and back feeding because whole huge truck box was not grounded, even though it was bolted to frame. I hooked alligator clip of ice pick test light to truck box and stabbed it in rusty frame...... it lit.

Dad sold cars and sometimes got fun stuff as trade-ins. At 15 was planning on driving a 125 CC Yamaha to high school. . Then when riding at dad's garage I almost missed bumper of car parked in the back row by 6 inches, 8 stitches in shin. Still at full throttle was looking back admiring my first donut in the dirt.

Before that we got a Honda 2 or 4 cylinder 500CC as a tradein. Was "racing" a friend around a building, I didn't know it's power ,reved it up and popped the clutch. Front of bike came up and almost landed behind me. Front wheel bounced on ground ~4 times till I got it under control, handle bars were turned on 1-st landing.

Last edited by len k; 09-13-2017 at 08:11:00 PM.
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  #209  
Old 09-13-2017, 07:42:09 PM
David C David C is offline
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Default Re: An Onan JB Performance Question

Leon,
When you get around to pulling the fan shroud to check the gear mesh into the ring gear, take a heat gun and heat the starter drive up a little and see how it acts. If it acts up, with solenoid being cold, the drive is bad.

If the starter motor is spinning, the solenoid is doing its job correctly. In the mid 80's, GM had starter solenoid problems on their motor home chassis when they got hot. They added a Ford looking solenoid to power up the starter solenoid. I believe they used 10 gauge to and from the Ford solenoid.

David C.
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  #210  
Old 09-13-2017, 10:12:36 PM
Leon N. Leon N. is offline
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Default Re: An Onan JB Performance Question

David C tomorrow I will try your suggestion with the heat gun. I will heat up the solenoid without starting the JB. I cannot heat up the starter bendix since it is enclosed. BTW, That is a new bendix. When I get around to returning the starter to the shop, one of their tests will be a locked rotor test to check out the bendix AND see if the armature is spinning on the shaft. Can you believe that?!

I will attempt to crank the flywheel and see if the pinion disengages. I really do not need to remove the fan shroud because during just about every attempt the flywheel is spun before the pinion disengages. I will also measure any voltage difference between the shifter solenoid case and the battery negative terminal.

Note, when the pinion disengages and the starter whines, there still is 11+ volts at the small terminal on the solenoid. If I have enough energy, I will remove the front shroud and confirm that not to exceed 1/8 inch clearance between the pinion and the ring gear and also check for full engagement. I have to restore the shroud to keep my JB on standby.
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  #211  
Old 09-13-2017, 10:45:22 PM
len k len k is online now
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Default Re: An Onan JB Performance Question

Skiming manuals in past, locked rotor test looks like just to see that starter can make enough torque. Detecting loose armature is just a side benefit.

Can see how with poor factory quality control a thermal or force shrink fit might be too loose. But seems a stretch to believe it can start engine when cold, then slip when a little warmer . Suspect Onan bought their starters pre-assembled from other companies.

I'm still thinking solenoid

Last edited by len k; 09-14-2017 at 01:12:34 AM.
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  #212  
Old 09-14-2017, 11:17:20 AM
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Default Re: An Onan JB Performance Question

I'm thinking with ~ 11 V at solenoid, the wiring and control box components are good. But very easy test for them while hot is: Short small solenoid terminal directly to fat bat bolt on solenoid. Using copper rod/bar would be best, but easiest to use a large screwdriver, with insulated handle( possible inductive back voltage ). Don't hold gen frame, that completes the circuit.

Likely will be good spark (100amp solenoid), keep it tight and don't lose your nerve. Safety glasses and long sleeves will help you feel safe.

Last edited by len k; 09-14-2017 at 04:38:16 PM.
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Old 09-14-2017, 04:44:05 PM
Leon N. Leon N. is offline
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Default Re: An Onan JB Performance Question

I have some bad news! Things just got worse. I disconnected the gas supply so that the JB would not start. I was conducting len K's test. that is, measured the voltage from the solenoid shifter case to the battery ground terminal. Was surprised to see between 0.25 and 0.5 volts! Gonna make sure the repair shop knows this.

Then to my surprise the starter would not stop cranking the flywheel. I tried the spring loaded start stop switch to no avail, I forced the centrifugal switch closed once again to no avail. In the meantime the pinion disengaged and the starter whined on and on until I detached the positive terminal at the battery. Holey Cow! Must have taken me a good minute to shut down the starter.

Next, disconnected the start/stop switch and checked it out with an ohm meter Checked OK so I reinstalled the start/stop switch. Come to think of it if the centrifugal switch did not shut down the starter, then that spring loaded start/stop switch was not the problem.

So next I tried reattaching the battery positive cable and nearly got knocked on my A as the starter tried to start. So I stopped that effort but noticed my trickle charge was pegged at 5 amperes! Next I measured the voltage at the small terminal on the shifter solenoid and read zero volts. Rats.

I suspect the shifter solenoid main contacts are stuck (welded?) closed. So tomorrow I will remove the starter and off to the repair shop. I do want the old shifter because I think len K is correct. Looks that solenoid failed.
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  #214  
Old 09-14-2017, 05:31:54 PM
Wayne 440 Wayne 440 is offline
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Default Re: An Onan JB Performance Question

Leon, you have more tolerance and patience than I do. If that were my set, I would have put a Mitsubishi starter on it after the first failure of the "rebuilt" unit.
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  #215  
Old 09-14-2017, 06:05:10 PM
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Default Re: An Onan JB Performance Question

Quote:
Originally Posted by Leon N. View Post
I have some bad news! Things just got worse. I disconnected the gas supply so that the JB would not start. I was conducting len K's test. that is, measured the voltage from the solenoid shifter case to the battery ground terminal. Was surprised to see between 0.25 and 0.5 volts! Gonna make sure the repair shop knows this.

Then to my surprise the starter would not stop cranking the flywheel. I tried the spring loaded start stop switch to no avail, I forced the centrifugal switch closed once again to no avail. In the meantime the pinion disengaged and the starter whined on and on until I detached the positive terminal at the battery. Holey Cow! Must have taken me a good minute to shut down the starter.

Next, disconnected the start/stop switch and checked it out with an ohm meter Checked OK so I reinstalled the start/stop switch. Come to think of it if the centrifugal switch did not shut down the starter, then that spring loaded start/stop switch was not the problem.

So next I tried reattaching the battery positive cable and nearly got knocked on my A as the starter tried to start. So I stopped that effort but noticed my trickle charge was pegged at 5 amperes! Next I measured the voltage at the small terminal on the shifter solenoid and read zero volts. Rats.

I suspect the shifter solenoid main contacts are stuck (welded?) closed. So tomorrow I will remove the starter and off to the repair shop. I do want the old shifter because I think len K is correct. Looks that solenoid failed.
You know Leon, For a guy that said you are "80 something" years old, my hat is off to you! You have "Old School" TENACITY some of which I hope to still have in 15-20 years... Just turned 65!
I'll bet you were Hell on wheels in your younger years...And I say that with respect.
I DO agree with Wayne440. JUNK that Dinosaur Prestolite starter and replace it with a Mitsubishi. If you really wanted to save the Prestolite starter, Make a TROPHY base for it and bolt it on to the trophy base and put it on your fireplace mantle.
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Old 09-14-2017, 06:31:04 PM
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Default Re: An Onan JB Performance Question

Your doing well Leon, I'm ~ 60 and slowing down.

.25 to .5 V solenoid case to ground is not too bad, case is steel and steel is ~ 8X resistance of copper. At 100 amps .5V is ~ .005 ohm.

With solinoid jamming when given a good power source with low source resistance I would look for bad control box connections and wiring. Sounds like some higher resistance limited current in past. Common practice to test solenoid with a shorting screwdriver.

Guessing solenoid jammed. Would be interesting to open up solenoid. Maybe: rust, broken parts, copper bolt head with 1/8 " missing from arc erosion , ect. Copper washer contact is copper plated steel, on old ones copper is gone from arc errosion.

One of those switches that mount on bat terminal might not be a bad idea, also good if short and smoke. For my 7NHM I "temporarily" salvaged jumper cables and clamps from junk jumpstart bat pack. I just clamp them on lead bat post adapter, bites in well. Likely will be permanent

For quick disconnect of bat I use water pump pliers (long handle adjustable pliers.) Side post bats unscrew fast.

Likely starter motor didn't over heat. DC motors with no-load rev up and make more back EMF, reduces current. Schematic shows starter field and armature are in series on my JB spec AA, likely yours too.

Last edited by len k; 09-14-2017 at 08:14:04 PM.
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Old 09-14-2017, 07:32:14 PM
Leon N. Leon N. is offline
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Default Re: An Onan JB Performance Question

I am hoping this is the last and only major fix for my JB. I may be wrong but I suspect that starter solenoid shifter was of inferior quality. Will know when I get the old one back. I do not want to introduce non genuine Onan parts if I can help it. The original one lasted for 41 years, this one only 6 years.

I will query again but I did not get a good answer as to where and who the auto-electric shop is purchasing these solenoids. Obviously not from Onan.

Re len K's comment: "I would look for bad control box connections and wiring". I think the control box connections are OK. With the battery disconnected I noticed a few amperes flowing from the battery charger into the JB. That current was flowing from the JB B+ side directly into the positive terminal on the solenoid and thus through the starter to ground.

Note, my JB battery float charger is connected into the control box to a Pair of + and - terminals,

Yes , this is a pain to do because I have to remove the muffler, unbolt the two 4 x 4's, remove the front shroud and thermostatic shutters, then hoist the JB 6 inches, swing it 90 degrees to gain access to the starter. I am down on all fours and just quit for the night.

Checked the pinion to ring gear clearance and attached a picture best I can do. Looks like just about 3/16 inch clearance. Onan says max should be 1/8 inch. No shims were employed with my starter so I suspect this aspect is OK.
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  #218  
Old 09-14-2017, 07:40:58 PM
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Default Re: An Onan JB Performance Question

Quote:
Originally Posted by Leon N. View Post
I will query again but I did not get a good answer as to where and who the auto-electric shop is purchasing these solenoids. Obviously not from Onan.
Likely from ~ cheapest supplier he can find.

Few years ago for dad's 87 Chevy Caprice 305 V8 a starter shop said it would be ~$100 for rebuild. Because shop guy was ~ retired and we sent him a lot of business in past he told us that Advanced Auto Parts has starters for ~ $35 and a ~ $45-50 one came with ~ lifetime warentee. $50 one worked fine till we sold car several years later. Shop guy buys them and sells as rebuilt ( doesn't claim HE rebuilt it)

Last edited by len k; 09-14-2017 at 08:08:02 PM.
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Old 09-14-2017, 08:04:23 PM
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Default Re: An Onan JB Performance Question

"Looks like just about 3/16 inch clearance. Onan says max should be 1/8 inch. No shims were employed with my starter so I suspect this aspect is OK."

IF 1/8 is MAX and you are measuring 3/16 you are over the MAX by 1/16
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Old 09-14-2017, 08:18:19 PM
len k len k is online now
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Default Re: An Onan JB Performance Question

Easy enough to get some scrap steel , cut it up and drill some holes for a shim. $3 metal cutting abrasive disk on a carpenter's skill saw cuts steel real fast and easy, Home Depot.

Or car parts store for generic shims, might find something close enough.
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