Generators and Motors
[Home] - [HELP] - [Forums] - [Library] - [Photo Gallery] - [Groups] - [Classified Ads] - [Subscribe] - [Links] - [Books] - [Sponsors] -

Go Back   SmokStak > SmokStak® Vintage Electrical Equipment > Generators & Motors General Discussion > Onan Generators
Forgot Password? Join Us!

Notices

Onan Generators Restoring, operating and maintaining vintage Onan generators.

Onan Generators

A Bad Onan kind of day!


this thread has 26 replies and has been viewed 1342 times

Reply
 
Thread Tools Display Modes
  #1  
Old 04-10-2017, 01:32:01 PM
GMGuy GMGuy is offline
Registered-I
 
Join Date: Aug 2011
Location: Whitby, Ontario, Canada
Posts: 32
Thanks: 1
Thanked 7 Times in 4 Posts
Default A Bad Onan kind of day!

What are the chances, 2 Onans and no power. One wouldn't start and the other appears to have a bad Voltage Regulator.

So, Friday, I went up to my cottage 2 hours from the city to find a late season snowfall had taken the power out. No problem, I thought, I have my recently acquired JB 7.5 (705JB-3R/1P ser36C874768) I had run it 36 hours straight at Christmas without issue. I go to start it, and the battery is down in charge, so it wouldn't roll over. I then got a spare battery and it rolled over well, and fired intermittently on one lung, but would not catch. I could not get it to run, and didn't want to burn up the starter.
It was now getting dark, so I rolled out the Model 5.5 BGM F A 26105 H (Ser 0000 092795) Marquis 5500, and it fired right up. I haven not used it in a bit, so I took a meter just to check (better safe than sorry), and 60Hz, but over 200V at no load (yikes). Glad I checked, because I don't know how many things would have appreciated that over-voltage. 2 down....

On the up side, the power was restored just an hour later. I now have to diagnose the no-start and the likely bad voltage regulator.

Oh well, just another day, and the beer was still cold!

Ralph
Reply With Quote
Sponsored Links
  #2  
Old 04-10-2017, 01:50:46 PM
len k len k is offline
Registered-III
 
Join Date: Jun 2012
Location: Manchester, New Hampshire
Posts: 14,510
Thanks: 380
Thanked 5,235 Times in 3,815 Posts
Default Re: A Bad Onan kind of day!

Can always put the beer in the snow

Guessing fuel starvation on the JB, try squirting some gasoline down the carb to see if it will start. I've test run my JB on steady FINE THIN stream of gasoline from a squirt bottle down the carb ( ~ 1/32 inch dia, and even then had to stop squirting sometimes). IF runs check for gas flow to carb and clean the carb. Ethanol in gas gums up carb if it sits for several months.

BGM .... odd that it went to overvoltage, reg usually dies and it goes to 1-2 VAC. You might have gotten lucky and caught it before $270 reg died. Try cleaning the slip rings with scotchbrite pad. Lot of times they oxidize and get high contact resistance then kill the AC voltage reg. Takes bunch of months , maybe > 6, but I've measured 100 ohms between the brushes after ~ 3-4 months of sitting. Should be 20.25-24.75, (30 max.), with reg unplugged, engine off.

Last edited by len k; 04-10-2017 at 02:01:12 PM.
Reply With Quote
  #3  
Old 04-10-2017, 02:28:32 PM
GMGuy GMGuy is offline
Registered-I
 
Join Date: Aug 2011
Location: Whitby, Ontario, Canada
Posts: 32
Thanks: 1
Thanked 7 Times in 4 Posts
Default Re: A Bad Onan kind of day!

Won't be up until Friday, but will check them both, thanks Len!
Reply With Quote
  #4  
Old 04-10-2017, 02:50:30 PM
LRomero LRomero is offline
Subscriber
 
Join Date: Jun 2016
Location: New Iberia, Louisiana
Posts: 370
Thanks: 54
Thanked 125 Times in 82 Posts
Default Re: A Bad Onan kind of day!

A bad Onan day is still better than a good day at the office.
Reply With Quote
The Following 2 Users Say Thank You to LRomero For This Post:
  #5  
Old 04-11-2017, 07:45:55 AM
GMGuy GMGuy is offline
Registered-I
 
Join Date: Aug 2011
Location: Whitby, Ontario, Canada
Posts: 32
Thanks: 1
Thanked 7 Times in 4 Posts
Default Re: A Bad Onan kind of day!

I have to agree with that comment any day!!!

So, I did a little reading in the Marquis 5500 manual in the troubleshooting section and it says that if the frequency is correct (ie, the right RPM), but the voltage is high, then it is a failed Voltage Regulator.
I know Len, you said check the slip rings, but I would suspect that would result in a low voltage, not high.
I am thinking I will need a new voltage regulator.
Mr. Onan Parts, do you know if they are available and about how much?

Thanks
Ralph
Reply With Quote
  #6  
Old 04-11-2017, 08:16:52 AM
Billy J Shafer's Avatar
Billy J Shafer Billy J Shafer is offline
Subscriber
 
Join Date: Nov 2004
Location: Centerville, Texas
Posts: 16,226
Thanks: 8,263
Thanked 13,560 Times in 6,389 Posts
Default Re: A Bad Onan kind of day!

Quote:
Originally Posted by LRomero View Post
A bad Onan day is still better than a good day at the office.
Or working on a Genajunk unit.
__________________
I don't talk to myself. This early in the morning. Why the hell should I talk to you.
Reply With Quote
  #7  
Old 04-11-2017, 08:58:34 AM
LRomero LRomero is offline
Subscriber
 
Join Date: Jun 2016
Location: New Iberia, Louisiana
Posts: 370
Thanks: 54
Thanked 125 Times in 82 Posts
Default Re: A Bad Onan kind of day!

Quote:
Originally Posted by Billy J Shafer View Post
Or working on a Genajunk unit.
Amen to that.
Reply With Quote
The Following User Says Thank You to LRomero For This Post:
  #8  
Old 04-11-2017, 10:34:34 AM
len k len k is offline
Registered-III
 
Join Date: Jun 2012
Location: Manchester, New Hampshire
Posts: 14,510
Thanks: 380
Thanked 5,235 Times in 3,815 Posts
Default Re: A Bad Onan kind of day!

Quote:
Originally Posted by GMGuy View Post
I know Len, you said check the slip rings, but I would suspect that would result in a low voltage, not high.
Clean the slip rings anyways and try it. In my testing I found resistance varies around the slip ring, might confuse the reg.

Cleaning slip rings fixed the problem for other people that had voltage. I seem to remember one person that had high voltage......I think.
Reply With Quote
  #9  
Old 04-11-2017, 10:37:19 AM
GMGuy GMGuy is offline
Registered-I
 
Join Date: Aug 2011
Location: Whitby, Ontario, Canada
Posts: 32
Thanks: 1
Thanked 7 Times in 4 Posts
Default Re: A Bad Onan kind of day!

I will try before I buy!!!!
Reply With Quote
  #10  
Old 04-11-2017, 12:47:32 PM
OnanParts's Avatar
OnanParts OnanParts is offline
Sponsor
 
Join Date: Nov 2008
Location: Pacific Northwest, USA
Posts: 807
Thanks: 60
Thanked 959 Times in 424 Posts
Default Re: A Bad Onan kind of day!

Quote:
Originally Posted by GMGuy View Post
I will try before I buy!!!!
If cleaning the slip rings does not work..

http://www.flightsystems.com/p-ONAN-305-0826.html
Reply With Quote
The Following User Says Thank You to OnanParts For This Post:
  #11  
Old 04-11-2017, 01:01:28 PM
len k len k is offline
Registered-III
 
Join Date: Jun 2012
Location: Manchester, New Hampshire
Posts: 14,510
Thanks: 380
Thanked 5,235 Times in 3,815 Posts
Default Re: A Bad Onan kind of day!

Buy Flight systems standard 305 model and it's only ~ $225 , but mounting is slightly different.
Reply With Quote
  #12  
Old 04-12-2017, 08:00:08 AM
GMGuy GMGuy is offline
Registered-I
 
Join Date: Aug 2011
Location: Whitby, Ontario, Canada
Posts: 32
Thanks: 1
Thanked 7 Times in 4 Posts
Default Re: A Bad Onan kind of day!

Thanks for the info guys.
I will clean the rings this weekend and then determine if its good or not. I also picked up NGK B6L plugs for my JB, as I am not a fan of Champion. I have not looked at the current plugs, but it is the cheapest place to start.
Ralph

I should also do an oil change on the JB, what filter number is used on the 7.5 JB?

Thanks in advance, you guys know everything!
Reply With Quote
  #13  
Old 04-12-2017, 02:34:30 PM
Vanman Vanman is offline
Subscriber
 
Join Date: Aug 2011
Location: Mission Viejo, California
Posts: 3,165
Thanks: 3,901
Thanked 1,292 Times in 875 Posts
Default Re: A Bad Onan kind of day!

Might want to try checking / changing the points and condenser on the ill running JB. Had a condenser giving me fits before. It "tested" good with ohmmeter and a capacity meter, but was shorting out under actual operating voltage. I tried a new one "for the heck of it" and away she went!!
Reply With Quote
  #14  
Old 04-12-2017, 07:24:13 PM
dracer dracer is offline
Registered
 
Join Date: Apr 2017
Location: Klamath River, California
Posts: 36
Thanks: 0
Thanked 5 Times in 5 Posts
Default Re: A Bad Onan kind of day!

Quote:
Originally Posted by Vanman View Post
Might want to try checking / changing the points and condenser on the ill running JB. Had a condenser giving me fits before. It "tested" good with ohmmeter and a capacity meter, but was shorting out under actual operating voltage. I tried a new one "for the heck of it" and away she went!!
through the years I have found , the onan condensers go bad a lot
Reply With Quote
  #15  
Old 04-13-2017, 06:20:03 AM
GMGuy GMGuy is offline
Registered-I
 
Join Date: Aug 2011
Location: Whitby, Ontario, Canada
Posts: 32
Thanks: 1
Thanked 7 Times in 4 Posts
Default Re: A Bad Onan kind of day!

I will start with plugs this weekend, and while they are out, I will take a look in the jugs. If that does not get her to run, I will ensure I have spark and then go to carburation after that. I will let the group know how I make out.
I will certainly be distracted as it is ATV season, and I need to get my docks and boats in (if the ice is out....).
Thanks for the tips!
Reply With Quote
  #16  
Old 04-13-2017, 07:02:25 AM
willie1959 willie1959 is offline
Registered
 
Join Date: Apr 2016
Location: Apsley, Ontario, Canada
Posts: 49
Thanks: 0
Thanked 10 Times in 7 Posts
Default Re: A Bad Onan kind of day!

I am at Jack lake ice was still in bay Tuesday but my area was clear. For sure next week. Ice is normal this year, normally out around April 20 which is normal. Buying propane this week for gensets at Costco price the same as last year 0.59 a liter price no carbon tax increase cool, drops all summer. Going to rebuild my 4500 onan this summer. Found a low hour motor 150 vs 3700 to due swap and ordered a new slip ring for rotor. Current motor leaks oil out fan end but runs fine.
Reply With Quote
  #17  
Old 04-17-2017, 09:29:02 AM
GMGuy GMGuy is offline
Registered-I
 
Join Date: Aug 2011
Location: Whitby, Ontario, Canada
Posts: 32
Thanks: 1
Thanked 7 Times in 4 Posts
Default Re: A Bad Onan kind of day!

So weekend update on the 2 misbehaving Onans.

I did not even look at the Marquis 5500, seems that the beers were cold and in the way....

The 7.5 JB was my focus. I bought a set of NGK 6BL plugs and removed the possibly original Chumpions. They were nasty, one plug was crudded up right across the gap, no wonder it wouldn't run. Put the fresh plugs in and it fired right up. Seemed to be running well, then I noticed I had only put on 1 plug wire (but still was at 60HZ, I can't believe it). So, I shut it down, put on the other wire and wow, did it ever run smooth. Perhaps it has never run on 2 lungs since I got it. I ran it up to temp, and loaded it to about 3000w, and it didn't even grunt, oil pressure stayed 20-30psi.

I love this JB set. It rocks!!!
Reply With Quote
The Following 3 Users Say Thank You to GMGuy For This Post:
  #18  
Old 04-17-2017, 02:03:47 PM
grif grif is offline
Registered-III
 
Join Date: Oct 2011
Location: Yakima, Washington
Posts: 1,228
Thanks: 412
Thanked 317 Times in 234 Posts
Default Re: A Bad Onan kind of day!

Since being out of the orchard business,,, I kept an old MF50 with a bin lift on it. one cylinder fouls plugs after running 6 or 8 hours. I got in the habit of just swapping plugs to different cylinders every lunch break, that's got to be 20 years ago and still running just fine. The move to a clean cylinder would burn off the oil just fine.

Long version of saying, after you run it a few hours, pull the plugs to see if you've got anything going on.


Quote:
Originally Posted by GMGuy View Post
one plug was crudded up right across the gap, no wonder it wouldn't run. Put the fresh plugs in and it fired right up.

I love this JB set. It rocks!!!
Reply With Quote
  #19  
Old 04-17-2017, 02:15:06 PM
len k len k is offline
Registered-III
 
Join Date: Jun 2012
Location: Manchester, New Hampshire
Posts: 14,510
Thanks: 380
Thanked 5,235 Times in 3,815 Posts
Default Re: A Bad Onan kind of day!

When trying to start my yard plow truck in winter, I accidentally found heating the plugs till insulator is cherry red hot burns off all the oil and crud. Started right up after that.
Reply With Quote
  #20  
Old 05-30-2017, 07:49:08 AM
GMGuy GMGuy is offline
Registered-I
 
Join Date: Aug 2011
Location: Whitby, Ontario, Canada
Posts: 32
Thanks: 1
Thanked 7 Times in 4 Posts
Default Re: A Bad Onan kind of day!

Latest update from the weekend... still haven't looked at the Marquis 5500, but ran the 705 JB and it was doing fine, until.... it stopped outputting voltage. So, I stopped it and cleaned the slip rings, and then it started to produce power again.
The frequency was a bit low (about 56Hz), so I adjusted the spring and got 61Hz uploaded, but then noticed I had 307V AC
This is a Magneciter unit, so I started reading about what to check...

Hoping people can confirm, I should check the coils and Diodes, anything else? Is my Magneciter fried?
Reply With Quote
Reply


Thread Tools
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off

F o r u m Jump

Similar Threads Chosen at Random
Thread Thread Starter F o r u m Replies Last Post
Not Onan... Kind of an Orphan Motorhead Honda, Yamaha, Kawasaki, Isuszu Generators 17 11-03-2015 06:41:32 AM
Free new starter for some kind of Onan BigBlockChev Onan Generators 5 09-16-2014 04:19:17 PM
What kind of diesel engine would this Onan 12.5RJC have? 69zfarmer Onan Generators 3 11-11-2012 02:41:50 PM
What kind of wire is this on Onan BGA 5 gtj811 Onan Generators 3 11-12-2011 01:18:10 PM


Use "Ctrl" mouse wheel to change screen size.
All times are GMT -4. The time now is 05:37:20 PM.

Smokstak and Enginads site search!


All use is subject to our TERMS OF SERVICE
SMOKSTAK® is a Registered Trade Mark - A Community of Antique Engine Enthusiasts
Copyright © 2000 - 2016 by Harry Matthews P.O. Box 5612 - Sarasota, FL 34277