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Onan 4GBE spark problem


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  #21  
Old 03-06-2017, 11:52:00 AM
Pete Spaco Pete Spaco is offline
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Default Re: Onan 4GBE spark problem

Re magnet polarity:
It can matter big time. Check out Hall effect sensors, or go to:
https://www.youtube.com/watch?v=IWsqIPXExgo

Pete Stanaitis
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  #22  
Old 03-06-2017, 12:05:04 PM
len k len k is online now
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Default Re: Onan 4GBE spark problem

Can try drilling a magnet, but I think some are very hard. I like the way they are mounted in the video, the aluminum supports against centrifical stress and the epoxy just holds them from vibrating out. Onan had problems with magnet adhesive failing on their inverter gens ( HDKAJ types)

Polarity does matter , but from a practical standpoint you can mount the magnets, then if that doesn't work swap the polarity.

Or you can look at polarity of remaining rotor arm magnet and look at valve motion to determine what magnet polarity fires the coil before TDC. Can use an spare small magnet to match arm's polarity to new magnet. (On a compass the part of the needle that points north is compass magnet's south pole, went thru this at work.)

Last edited by len k; 03-06-2017 at 12:39:10 PM.
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  #23  
Old 03-06-2017, 05:38:02 PM
bbqjoe bbqjoe is offline
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Default Re: Onan 4GBE spark problem

I'm really close. I've got spark now.
The biggest challenge is keeping the magnets on for testing purposes
I've tried hot glue, zip ties, and bailing wire.
The stickler is that the backside of the fins are at an angle, so everything wants to slide towards the thinner end.

I believe I'll drill a hole in each corresponding fin, and use some of this stuff I have called PC 11.
It will severely hold two things never made to be held together, together.
It takes well over 24 hours for a full cure.

The next mission will be to set up the sensor a little better so I can slide it one direction or the other to adjust the timing.

The engine is burning ether and wants to start, but I think my timing is off just a hair or two.
It wants to run almost as bad as I want it to.

If I can get it to fire, I'll put the carb back on, and go from there I guess.

Also, this engine has never had a real snappy spark from day one.
It's never been a bright blue, more like a hot yellow.

I realize this is all very crude.
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  #24  
Old 03-06-2017, 06:12:38 PM
len k len k is online now
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Default Re: Onan 4GBE spark problem

When I was thinking of doing something like that I was thinking of using smaller cylindrical magnets say 3/16 inch in dia by ~ 1/2 inch long. Also I would drill into SIDE of flywheel, parallel to it's shaft axis so glue will not need to fight centrifugal force. ( less stress in the glue). I'm assuming there is clearance on side of flywheel , would guess magnet would only have to stick out 1/4 inch or less.

I would mount the ignition modual so it is adjustable to move to different angles, as firing angle before TDC will vary with how far ( strong) the magnet field reaches out to it. ( you'll have to trial and error it with a timing light)

One way to get magnets like this is use the magnet from a door alarm security sensor ( 3-rd link).

http://www.grisk.com/images/product_...re_magnets.pdf
http://www.grisk.com/images/product_...ty_magnets.pdf
http://www.grisk.com/images/product_..._press_fit.pdf <---- can disassemble this type to get the magnet.
http://www.grisk.com/magnetic-reed-switches.php

Last edited by len k; 03-06-2017 at 06:37:12 PM.
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  #25  
Old 03-06-2017, 09:47:02 PM
bbqjoe bbqjoe is offline
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Default Re: Onan 4GBE spark problem

https://www.youtube.com/edit?o=U&video_id=bE2SGqMLyZ4

There's some more work to do, butI'm doing a happy dance.

I think I need to go over all the internal connections in the box. For some reason it seems to briefly run better with a positive wire run to the positive terminal on the coil.

I'm guessing videos don't embed here?
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  #26  
Old 03-06-2017, 09:55:22 PM
Pete Spaco Pete Spaco is offline
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Default Re: Onan 4GBE spark problem

I just looked up neodymium magnets on Ebay. I noticed several styles that already have holes drilled in them! Some have straight holes and some are even countersunk.
I've used a 1/4" round X 1/16" thick solid version with Hall Effect sensors and they will work up to about a quarter inch away from the sensor reliably.

Several years ago, all four magnets let loose from the distributors, trigger wheel on a Genese "electronic ignition" kit the the previous owner had installed. It was due to a interference problem between the trigger wheel, the rotor and the top of the distributor cap. Caused enough heat to swell the trigger wheel and free up the cast-in-place magnets. Anyway, I JB Weld epoxied them back in place after fixing the interference problem and it has worked well ever since.

Pete Stanaitis
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  #27  
Old 03-06-2017, 09:58:45 PM
bbqjoe bbqjoe is offline
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Default Re: Onan 4GBE spark problem

https://www.youtube.com/watch?v=bE2SGqMLyZ4
Maybe this will work.
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  #28  
Old 03-06-2017, 11:31:08 PM
David C David C is online now
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Default Re: Onan 4GBE spark problem

If the module is the same part number as the system that uses the module under the flywheel, can an ignition rotor added behind the flywheel. I would bet the front cover has the mounting bosses for the module. This would make it an OEM setup. Below is link to an OEM setup.
http://www.ebay.com/itm/Genuine-Onan...cAAOSwY45UP9iq

Here is a link to a used rotor.
http://www.ebay.com/itm/CASE-Ingerso...YAAOSw5cNYcTme

David C.
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  #29  
Old 03-07-2017, 03:41:20 PM
len k len k is online now
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Default Re: Onan 4GBE spark problem

bbqjoe ..... well, anything could work. But I'ld want something stable that doesn't stand a chance of moving or falling off. That's why I recommend the small cylindrical magnets press fit or glued into holes drilled into flywheel, even if you have to make up a bracket to hold the ignition modual sensor. I'ld avoid drilling into fins if I could, or at least not the base of fins

I don't think you need LARGE magnets. Their large weight just makes for higher centrifugal forces trying to pull them off flywheel. The magnets are pulling ~550 G's at edge of flywheel. If magnet weighs 1 ounce then that's ~ 35 pounds of force trying to pull magnet off. I'm a mechanical engineer

Last edited by len k; 03-07-2017 at 04:41:29 PM.
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  #30  
Old 03-07-2017, 04:50:03 PM
bbqjoe bbqjoe is offline
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Default Re: Onan 4GBE spark problem

You've got one up on me, I've never driven a train.
JK

You're correct here.
The magnets are pure overkill, and were just an easy find for test porpoises.
I have a few magnets out of I hard drive that I will try next.

Thanks.
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  #31  
Old 03-10-2017, 04:40:37 PM
bbqjoe bbqjoe is offline
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Default Re: Onan 4GBE spark problem

Ok, this thing is just short of running, and I'm certain the carb is gunked.
I opened it up, and cleaned it all out.
I have a relay connected to the air filter assy. From looking at the manual, it appears it's happy little name is K5.

K5 says it's for LPG, which isn't being used.

Does this relay need to be hooked up for the generator to run, or is it just a beautifier as far as I'm concerned?
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  #32  
Old 03-10-2017, 05:19:32 PM
len k len k is online now
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Default Re: Onan 4GBE spark problem

Look in service manual 965-0528 page B5 ( pfd page 31 of 158)

It's likely K4 to power the choke and fuel pump. On my similar Onan 7NHM that's what relay on air filter powers.

Follow wires and see where they go. Wires are faintly ink with lables on ends that correspond to connector pin numbers in schematic
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  #33  
Old 03-10-2017, 07:11:15 PM
bbqjoe bbqjoe is offline
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Default Re: Onan 4GBE spark problem

Well, I hooked K5 back up.

Here's what I have now after a thorough cleaning of the carb.

https://www.youtube.com/watch?v=bE2SGqMLyZ4&t=13s

Next issue: Not producing AC.
I will have to check at the breaker maybe.
Where/what else should I be checking?

Thank you.

Done for today though.

---------- Post added at 06:11:15 PM ---------- Previous post was at 06:07:02 PM ----------

Ooops wrong video


https://www.youtube.com/watch?v=SYpjE1docyg
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  #34  
Old 03-10-2017, 07:23:40 PM
len k len k is online now
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Default Re: Onan 4GBE spark problem

Don't want to run it long without the cooling sheet metal on it. They direct air over the block and heads to cool them.

To make AC check that control board flashes pin 7 of AC reg with ~ 9-12VDC WRT frame as it cranks. If yes put voltmeter across slip ring brushes and crank engine should be some voltage there, maybe 6-12 VDC. If it starts making AC that voltage can rise to 36 -60 VDC, so start with a high scale on voltmeter
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  #35  
Old 03-10-2017, 07:49:31 PM
bbqjoe bbqjoe is offline
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Default Re: Onan 4GBE spark problem

Thank you for your response Ken.

Could you break it down for me a little in layman's terms?
Flashing?
Slip rings? WRT?

Arg!
Sorry.


Joe
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  #36  
Old 03-10-2017, 08:12:17 PM
len k len k is online now
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Default Re: Onan 4GBE spark problem

Flashing = briefly powering the rotor to magnetize it
WRT = with respect to ,,,,,,,,,,( ei pin 7 WRT frame,,,,, means measure between pin 7 and frame)

--------------
Translation...

To make AC, check that control board powers pin 7 of AC reg with ~ 9-12VDC as you hold down start button ( measure between pin 7 of AC voltage reg and metal frame.

See service manual page 8-14 . On the genhead near end, above control box, there is a black plastic cover ~ 3 x 3 inch, under it are slip rings and brushes. The AC voltage reg supplys power to the brushes, they ride on slip rings of the rotor and rotor electromagnet is powered by slip rings.

If have power at pin 7 of reg, then put voltmeter across slip ring brushes and crank engine. Should be some voltage there, maybe 6-12 VDC. If gen starts making AC voltage at brushes can rise to 36 -60 VDC, so start with a high scale on voltmeter

Last edited by len k; 03-10-2017 at 08:30:01 PM.
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  #37  
Old 03-10-2017, 08:26:48 PM
bbqjoe bbqjoe is offline
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Default Re: Onan 4GBE spark problem

Does this look right, or do I have issues here too?
Sorry, very hard to get a pic inside there.


Thank you for all your attention.

Joe
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  #38  
Old 03-10-2017, 08:32:58 PM
bbqjoe bbqjoe is offline
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Default Re: Onan 4GBE spark problem

Pin 7? Are we talking pin #7 on the control board, right?
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  #39  
Old 03-10-2017, 08:39:00 PM
len k len k is online now
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Default Re: Onan 4GBE spark problem

pic in Post 37 is the brushes that ride on slip rings. That's a conivient placed to probe the voltage
Also check that they are free in their holder, not cracked or worn ( see service manual page 8-154 to measure for wear)

pin # 7 ...no, not on control board , on AC voltage reg ( VR1) it has the 12 pin connector ( 3 collumns of 4 pins)

page 8-15 of service manual , for alignment note plastic around pins 1/3/11 are D shaped also wire should be faintly inked with the number 7 near connector ( on gen harness side of connector0
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  #40  
Old 03-10-2017, 08:57:15 PM
bbqjoe bbqjoe is offline
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Default Re: Onan 4GBE spark problem

Ok. Are the pins checked when coupled at the connector, or is the connector separated when checking?

Sorry to be so inexperienced.

Joe
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