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Onan Emerald 1 Genset Questions


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  #1  
Old 10-06-2017, 07:28:25 PM
Imlost Imlost is offline
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Default Onan Emerald 1 Genset Questions

Hi. I'm the new owner of a relatively low hour (450) Emerald 1. Model 4.0 BGE-1R-26101C, S/N HS60 835287.
It hadn't been running in over 1yr. I changed the oil & filter, cleaned the carb, replaced the end bearing, cleaned the slip rings, and removed about 3lbs of dirt dauber nests.
It runs and puts out power. It doesn't run "rock steady" though. If I use the service manual carb settings (1 turn out on the idle, and 1 1/4 turns out on the main) it hunts quite a bit. If I turn the idle out 2- 2 1/2 turns and the main out 1 1/2- 2 turns it's pretty steady but still hunts a little.
No load voltage varies from about 118 to 122, under light/medium load (10gal Shop Vac) voltage varies from about 114 to 124, and the engine hunts whether no-load or load. Is the hunting going to be strictly a governor adjustment? Thanks in advance for any help.
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  #2  
Old 10-06-2017, 07:44:44 PM
len k len k is online now
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Default Re: Onan Emerald 1 Genset Questions

Gov adjustments can effect hunting , but having to open up the mix jets sounds like carb is bit plugged.

First thing I do on a new to me engine is pull the carb and clean it. These days with ethaonal in the gas carbs crud up when they sit. Also most lawnmower carbs have either water, dirt, or crud in the carbs. Carb on my similar NHM gen was so plugged up it hunts BADLY and bearly ran, cleaned the carb and it was perfect. Didn't bother with new parts either.
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Old 10-06-2017, 08:02:35 PM
Imlost Imlost is offline
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Default Re: Onan Emerald 1 Genset Questions

I removed the carb and soaked it in carb cleaner (the old style stuff that came in 5gal pails, stinks to high heaven, and actually cleans carbs). after rinsing I sprayed Brakeclean through all the orfices and they all appeared to be clear. I have not gapped the point or adjusted the valves yet.
I'm guessing I need to be methodical and follow the service manual to a T. I've been a mechanic for about 45yrs I've just never messed with generators much.
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Old 10-06-2017, 08:11:06 PM
len k len k is online now
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Default Re: Onan Emerald 1 Genset Questions

I have a similar 7NHM your carb many be similar. After removing the carb bowl, mine had 2 long screw in jet tubes in the dip tube casting. One was hiding behind a screw in cap. Each jet tube had 8 tiny cross holes that were plugged.

I take main jet apart and clean the tapered needle valve with steel wool. There's usually some crud in there if they sit a long time. I scrub out carb bowl with a tooth brush or steel wool if needed.

I only use gasoline, seems to work well on the ~ 75 small engines I've cleaned. Cheaper than carb cleaner too. I've found taking carb apart and physical cleaning seems to work better than any chemical cleaning. I blow out the passageways with compressed air . Don't forget about the 3-4 tiny ~ 0.010 inch ports in carb throat.

I never bother with new parts, always seems to run perfect. Only time I bought a carb kit was when float seat was leaking. But that carb was heavily water corroded and float valve seat was damaged
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Old 10-06-2017, 08:29:57 PM
Imlost Imlost is offline
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Default Re: Onan Emerald 1 Genset Questions

Yep. I use strands of wire to clean the small holes in the emulsion tubes and idle jets (I work on motorcycle carbs quite a bit). When I sprayed the Brakeclean through the passages all of the idle transfer holes in the throat were clear. That's why I'm wondering if it's something other than carb related.
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Old 10-06-2017, 08:35:18 PM
len k len k is online now
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Default Re: Onan Emerald 1 Genset Questions

Might check the 3-4 tiny 0.010 inch dia idle ports by the throttle butterfly, I had one heavily corroded carb that I had to ram them out with a shirt pin.
------------

Gov has 2 adjustments, rpm and sensitivity. Service Manual describes how to adjust gov, my gen has electronic gov so I didn't get into that.

Set the gov sensitivity too high and it will hunt. There is also some interaction between mix settings and gov, both can reduce hunting. I'ld adjust carb first, Manual should have instructions on how to adjust carb, once that is set right then I'ld adjust gov. Read manual but I believe manual says adjust idle mix at low rpm, and main mix at full load.

Dry out carb before running, Historically brakeclean is a chlorinated solvent, burn a tiny bit and it makes a very poisonous WW1 gas, phosgen. A little wiff can kill fast. https://www.smokstak.com/forum/showt...hlight=phosgen

Last edited by len k; 10-06-2017 at 10:45:02 PM.
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Old 10-07-2017, 06:48:38 AM
Kevin K Kevin K is offline
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Default Re: Onan Emerald 1 Genset Questions

Because both the main and idle jets need to be opened up considerable more than the starting settings, you might think about checking the float adjustment. The fuel level in the bowl may be low.

Hunting can also be caused by an air leak in the intake manifold gaskets. If I remember correctly, those gaskets need to be oriented correctly or there will be an air leak.

The intake manifold itself is a split design that may develop an air leak between the two pieces. I had a 4.5BGD with that problem. It ran great up to a load of about 3,000 watts, then surged as the load was increased. Sealing the two halves of the intake manifold cured it.
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Old 10-11-2017, 10:30:17 AM
Imlost Imlost is offline
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Default Re: Onan Emerald 1 Genset Questions

I got in a hurry and never checked the float level. DOH! Yeah, it wasn't right. While I was at it I replaced the plug wires, adjusted the valves, and ran a bead of sealer along the intake manifold parting line. Bought a Kill-A Watt meter, fired it up, tinkered with the governor and carb adjustments a little, and I'm a happy camper. With a 12A load it holds between 61.9 to 62.5 hz. I'm guessing that's close enough for govt. work.

Started it up a couple of hours later and once it warmed up it started making a horrendous racket. It spit a couple of gray/black plastic pieces out of the cooling air discharge, made a little more racket, and then quieted down. I shut it of and investigated. There were a few more plastic pieces, a spring, and a metal split retainer in the discharge grill. Pulled the starter and saw the spring cover in the fins of the engine, the rest of the pinion parts are what got spit out. The starter gear was still on the starter but it has some chewed up teeth. Got a new starter ordered, should be here Fri.

Thanks for the help. Much appreciated.
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  #9  
Old 10-17-2017, 10:42:45 AM
Imlost Imlost is offline
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Default Re: Onan Emerald 1 Genset Questions

Couple of more questions.
Do you set the valve clearance hot or cold?
Does this genset charge the battery when it's running?
Model 4.0 BGE-1R-26101C, S/N HS60 835287.
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Old 10-17-2017, 11:09:45 AM
Kevin K Kevin K is offline
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Default Re: Onan Emerald 1 Genset Questions

The valve clearance is set with a cold engine.

I'm attaching the production order and wiring diagram. The diagram shows a typical rudimentary battery charging circuit of a diode and resistor, which is usually set up more to prevent the battery from discharging than to charge it, a task usually done by the motor home battery maintainer. But you need to check for yourself. The one thing you can always count on with a used generator: "You never know what a previous owner has done".

Your serial number is incorrect.You might want to check it again.
Attached Files
File Type: pdf 40BGE1R26101C.pdf (19.2 KB, 13 views)
File Type: pdf 611-1174.pdf (87.3 KB, 16 views)
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  #11  
Old 10-17-2017, 12:27:45 PM
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Default Re: Onan Emerald 1 Genset Questions

Model 4.0 BGE-1R-26101C, S/N H860 835287
As I get older my eyesight gets worse. LOL!

With the genset running I'm getting about 12.5v at the battery and a little over 14v at the ignition coil, so I'm guessing the unit doesn't really keep the battery charged. I'm probably going to wire up a battery maintainer/charger so that when the generator is running it will charge the battery.

Thanks
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Old 10-17-2017, 12:35:06 PM
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Default Re: Onan Emerald 1 Genset Questions

Something is wrong, should not be getting higher voltages at spark coil than at bat.

Maybe connections are dirty somewhere, test meter ?? fuse?? .......
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Old 10-17-2017, 05:00:33 PM
Imlost Imlost is offline
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Default Re: Onan Emerald 1 Genset Questions

I've cleaned all the connections, new control board w/new fuse, test meters are pretty accurate: Fluke EC73III & Simpson 260.
The Spec plate line for DCV, amps & watts is unstamped (blank). Would that indicate no 12v charge capability?

Unit is low hrs, and doesn't appear to have had any previous owner "modifications". I've already taken all the sheetmetal off and removed all dirt dauber nests, removed the stator/housing to replace the bearing, cleaned/polished the slip rings & brush holder. Haven't seen any cut/spliced/non-factory crimped wires.
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Old 10-17-2017, 05:38:12 PM
Kell1961 Kell1961 is offline
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Default Re: Onan Emerald 1 Genset Questions

The Onan emeralds do not have a charging circuit. They are designed to use the coach inverter to charge the house batteries. Some of the older units did have a charge circuit but to many of the OEM builders tried to use the genset charging curcuit to keep the house batteries up under DC loads. A small battery tender or a battery charging assembly off of a commercial mobile will work.
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Old 10-17-2017, 05:43:40 PM
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Default Re: Onan Emerald 1 Genset Questions

BGE spec a-c SERVICE manual 965-0530 shows a simple bat charging circuit, resistor and single diode . pfd page 7
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  #16  
Old 10-17-2017, 05:51:49 PM
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Default Re: Onan Emerald 1 Genset Questions

OK. I guess I'll pull the resistor out tomorrow and make sure the connections on it are clean.
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Old 10-17-2017, 06:26:50 PM
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Default Re: Onan Emerald 1 Genset Questions

If your seeing 14V at bat and it's real, not a meter problem, there has to be a charger somewhere. Bat only makes about 12.6-12.8 after it's been ~day or so after it's last been charged.
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Old 10-17-2017, 06:37:50 PM
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Default Re: Onan Emerald 1 Genset Questions

With the engine running I'm seeing 12.5V at the battery and a little over 14V at the ignition coil.
So the generator is making 14V, it's just not getting back to the battery
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Old 10-17-2017, 06:53:55 PM
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Default Re: Onan Emerald 1 Genset Questions

Something is wrong, doesn't sound like bat is being charged. Check that it's wired as per the schematic. Never know how the previous owner modified (screwed up) things.

Only other thing I can think of is charging is applied close to spark coil , and there is resistance between bat and spark coil , so meter is responding to peaks of AC sine wave.
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Old 10-25-2017, 01:16:50 AM
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Default Re: Onan Emerald 1 Genset Questions

Couple of more questions.
1. I'm going to be mounting this unit on the deck of a flatbed truck. How high off the deck will it need to be for the cooling air exhaust to work properly without a cutout in the deck?

2. When mounting the unit do you mount it so that the top edge of the drip pan is level, or do you mount it so that the engine/generator is level?
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