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

ONAN 6.5 NH-3CR/16004K Just starting out with this, first steps?


this thread has 11 replies and has been viewed 455 times

Reply
 
Thread Tools Display Modes
  #1  
Old 10-10-2017, 12:40:04 PM
Runslow Runslow is offline
Registered
 
Join Date: Oct 2017
Location: Mesa, Arizona, USA
Posts: 5
Thanks: 5
Thanked 1 Time in 1 Post
Default ONAN 6.5 NH-3CR/16004K Just starting out with this, first steps?

First off some specs on the machine:
Model: ONAN 6.5 NH-3CR/16004K
Serial: J783388910

Hey guys, so I found this generator for $100 over the weekend. Allegedly the only problem was a bad ignition coil. I tried to hook it up to my jeep with Jumper cables and it wouldn't turn over, but they were 25 foot 4 gauge jumpers and the lead going to the solenoid was another 6 gauge wire that was probably 10 feet long and a bit corroded looking. The solenoid did snap when I clicked the starter, but the engine only tried to turn a bit (enough to puff once) and gave up. I'm hoping that the 50 feet of questionable wire was just not enough to turn over the whole exciter crank setup. I did however take the cover off the end of the generator side and spun it over with a drill pretty easy, and measured 135 PSI in both of the cylinders. I spun it Clockwise from that side (generator side) so I'm not sure if that's backwards for this motor, but it seemed fine.

First things first, the Twinslan site seems down so I'm wondering if someone would be so kind as to email me the documentation (repair manuals, whatever) that apply to my machine. I've searched and it seems like all the links have been taken down or are offline. My email is Cody@(myusername).com (of course, change that domain to Runslow.com)

Second, I have a few questions, forgive me if they're dumb ones. I see people refer to exciter starter here which I had thought was using the coils of the generator itself to turn over. After taking the end cap off the generator, there's coils and brushes there so I'm assuming it's actually powering it's own little starter built onto the end of the generator, is that correct?

Then also I'm wondering about the dual coil. Is it worth it to just buy a new Onan or Harley coil or something, or should I use two single coils? And if I've go that route, I've seen on this site people say to hook them in series and other people to hook them in parallel. If anyone can chime in on the best way to wire those, I'd appreciate it.

And finally, any unsolicited advice is welcome! Did I get an OK deal on this, or is it something you wouldn't have touched? Anything you see interesting about this genset, or any suggestions or advice or pitfalls to avoid? I don't have a specific use for it at the moment, I live in Phoenix so it's unlikely a natural disaster will take out power for a long time but you never know.
Attached Thumbnails
Click image for larger version

Name:	IMG_20171009_082703.jpg
Views:	65
Size:	163.7 KB
ID:	293258   Click image for larger version

Name:	IMG_20171009_082742.jpg
Views:	73
Size:	144.9 KB
ID:	293259   Click image for larger version

Name:	IMG_20171009_082753.jpg
Views:	70
Size:	191.0 KB
ID:	293260   Click image for larger version

Name:	IMG_20171009_082806.jpg
Views:	67
Size:	166.9 KB
ID:	293261  

Reply With Quote
Sponsored Links
  #2  
Old 10-10-2017, 12:41:06 PM
Runslow Runslow is offline
Registered
 
Join Date: Oct 2017
Location: Mesa, Arizona, USA
Posts: 5
Thanks: 5
Thanked 1 Time in 1 Post
Default Re: ONAN 6.5 NH-3CR/16004K Just starting out with this, first steps?

And it only let me do 4 attachments, I hope it's allowed to post again with more, here's the second set of pics.
Attached Thumbnails
Click image for larger version

Name:	IMG_20171009_082819.jpg
Views:	62
Size:	152.9 KB
ID:	293262   Click image for larger version

Name:	IMG_20171009_082842.jpg
Views:	57
Size:	151.8 KB
ID:	293263   Click image for larger version

Name:	IMG_20171009_082846.jpg
Views:	59
Size:	131.1 KB
ID:	293264   Click image for larger version

Name:	IMG_20171009_082854.jpg
Views:	55
Size:	128.4 KB
ID:	293265  

Reply With Quote
  #3  
Old 10-10-2017, 02:22:22 PM
nothingbutdarts nothingbutdarts is offline
Sponsor
 
Join Date: Apr 2014
Location: Bailey, Colorado, USA
Posts: 2,117
Thanks: 4,673
Thanked 934 Times in 632 Posts
Default Re: ONAN 6.5 NH-3CR/16004K Just starting out with this, first steps?

Great pictures. It take a GOOD battery and good cables to get them to crank. (Exciter cranked) No long battery cables!

Clean the points, common for not getting spark because of them. Waste spark coil as in BOTH plugs have to be attached and grounded to get spark.
I do believe though a Harley coil can work.

Good units and I bet you get it working! I can't help you with manuals but, others here can.

The fuel pump sometimes can be persuaded to work after cleaning.

Born on: October 1978
Reply With Quote
The Following User Says Thank You to nothingbutdarts For This Post:
  #4  
Old 10-10-2017, 06:45:10 PM
Max Thompson Max Thompson is offline
Sponsor
 
Join Date: May 2009
Location: N.W. Missouri, USA
Posts: 5,717
Thanks: 4,951
Thanked 5,252 Times in 2,873 Posts
Default Re: ONAN 6.5 NH-3CR/16004K Just starting out with this, first steps?

For $100 you can't be hurt too bad, worth that as a learning project.

I do not see the elec. choke assy. on the side of the carb. Not a big deal, you can rig up a manual choke. A couple shots of oil in each cylinder will save some wear until it wakes up and pumps some oil.

Pull the fan off the gen-end and grease the bearing behind it as a PM item.

As Darts said, it takes a good battery and cables to start these things, often referred to around The Stak as a "Big Fooken Battery".
Reply With Quote
The Following 3 Users Say Thank You to Max Thompson For This Post:
  #5  
Old 10-10-2017, 08:18:55 PM
wxyoung2008 wxyoung2008 is offline
Email NOT Working
 
Join Date: Jul 2011
Location: Dallas, Texas
Posts: 279
Thanks: 166
Thanked 60 Times in 34 Posts
Default Re: ONAN 6.5 NH-3CR/16004K Just starting out with this, first steps?

Once you get it running you will find it to be a rock-solid machine. It is my go to machine.
If you have to replace the fuel pump as they often go bad or leak a lot, go on EBAY and find you a $20 replacement unit.. Otherwise they can be expensive to replace.
Reply With Quote
The Following User Says Thank You to wxyoung2008 For This Post:
  #6  
Old 10-10-2017, 08:36:21 PM
len k len k is online now
Registered-III
 
Join Date: Jun 2012
Location: Manchester, New Hampshire
Posts: 14,504
Thanks: 380
Thanked 5,231 Times in 3,812 Posts
Default Re: ONAN 6.5 NH-3CR/16004K Just starting out with this, first steps?

If it doesn't turn don't keep cranking power on too long, you can burn the commutator segments $$$$.


My experience with jumper cables is point contact of jumper clamp to brass bolt post has enough resistance to not allow starter to crank. And that was on a NHM gen that takes maybe 1/2 the cranking amps of a NH. So good idea to use battery terminals instead of jumper clamps

Need short fat wires.
Ignoring the jumper clamps, I ran some quick numbers in a spreadsheet for just the wire losses and:
-- 25 ft jumper of 4 AWG is 50 ft round trip and .012 ohms total.
-- 10 ft of 6 AWD is .003 ohms, sounds low right? BUT:
Assuming 300 amp starting current from V=IR that's a 4.5 V loss in the cables, That sounds TOO MUCH!!!

Last edited by len k; 10-10-2017 at 09:29:02 PM.
Reply With Quote
The Following User Says Thank You to len k For This Post:
  #7  
Old 10-11-2017, 06:38:43 AM
MBB MBB is online now
Registered-III
 
Join Date: Apr 2009
Location: Elk Grove Village IL USA
Posts: 3,038
Thanks: 1,293
Thanked 2,282 Times in 1,256 Posts
Default Re: ONAN 6.5 NH-3CR/16004K Just starting out with this, first steps?

Here is a little information for you. I sent two manuals with two more to follow.
Enjoy. Welcome to the Stak.
Attached Files
File Type: pdf 65NH3CR16004K.pdf (35.0 KB, 10 views)
File Type: pdf 611-1135.pdf (198.8 KB, 13 views)
Reply With Quote
The Following 4 Users Say Thank You to MBB For This Post:
  #8  
Old 10-11-2017, 03:59:47 PM
Runslow Runslow is offline
Registered
 
Join Date: Oct 2017
Location: Mesa, Arizona, USA
Posts: 5
Thanks: 5
Thanked 1 Time in 1 Post
Default Re: ONAN 6.5 NH-3CR/16004K Just starting out with this, first steps?

Thanks everyone so much for the suggestions, and especially thanks for the manuals! Those will be invaluable in getting this thing ticking again.

So I've got an old Group 24 battery out in the shop, I pulled it out and plan to exchange it today for a fresh one. I've got some leftover 2 gauge I can throw some terminals on and wire it up, that should definitely be enough to kick this thing in the pants and get her spinning. I'm not going to pick up new coils quite yet, I'll check the spark after I clean the points and see if that doesn't help a bit. I'll post an update here this afternoon or tomorrow with how that all goes, but thanks again for the advice offered!
Reply With Quote
The Following User Says Thank You to Runslow For This Post:
  #9  
Old 10-12-2017, 03:55:21 AM
Runslow Runslow is offline
Registered
 
Join Date: Oct 2017
Location: Mesa, Arizona, USA
Posts: 5
Thanks: 5
Thanked 1 Time in 1 Post
Default Re: ONAN 6.5 NH-3CR/16004K Just starting out with this, first steps?

Well good news, I ended up picking up a bigger battery good for 800CCA. It turns over just fine now, which is a relief. Also cleaned the point. No spark on the plugs, but there was also no power running to the coil. There was a wire running near the coil with a spade connector on it that was 0 volts while off, but 12 volts while cranking so I assume that was the coil power. The weird thing is, though, the coil just has screw terminals and no spade terminal block, so Iím not sure what the story behind that is. The coil also had a new-looking bright yellow wire that was attached to the negative terminal that was clipped, and I canít find the other end of it. Could have just hastily been taken out of another genset or something, I donít know.

I pulled the coil out and replaced it with a single coil just to check spark in that case. Sure enough, spark but it looked fairly weak and I couldnít get it to fire. I also noticed that the spark was intermittent after a few seconds of cranking. I hammered the gap down just a touch, enough to get a consistent (again if slightly weak looking) spark out of it. I threw the plug back in, poured some gas down its throat, and sure enough even one one cylinder it tried to roar back to life.

So next I plan to pick up a real dual coil so I can get it running on both sides. The fuel pump line is also cut, so I need to repair that as well. I donít see why I couldnít run a wire from the positive side of the coil to the fuel pump, they should always both be on or off as far as I can tell. (I havenít looked at schematics yet, that may already be how it was wired).

Anyways, itís looking promising, though I did spend more on the battery now than I have the whole generator itself. Thanks again for the help, Iíll post again in the next few days when I have some more to tinker on Ďer.
Reply With Quote
  #10  
Old 10-12-2017, 10:26:12 AM
armandh armandh is offline
Sponsor
 
Join Date: Aug 2006
Location: Suburban St. Louis, Missouri
Posts: 2,629
Thanks: 169
Thanked 625 Times in 503 Posts
Default Re: ONAN 6.5 NH-3CR/16004K Just starting out with this, first steps?

I did my restore project on one starting just over a year ago.
https://www.smokstak.com/forum/showthread.php?t=161084
I found the points bad and the fuel pump bad.
other wise great from the same year as yours.
6 pages of restoration details
it belongs to my daughter now
Reply With Quote
The Following User Says Thank You to armandh For This Post:
  #11  
Old 10-14-2017, 04:09:33 AM
Runslow Runslow is offline
Registered
 
Join Date: Oct 2017
Location: Mesa, Arizona, USA
Posts: 5
Thanks: 5
Thanked 1 Time in 1 Post
Default Re: ONAN 6.5 NH-3CR/16004K Just starting out with this, first steps?

So just to be clear that I'm looking at the schematic correctly, the run ignition relay is activated by the low pressure switch which is grounded when pressure is high, and disconnected when pressure is low. Does that sound correct?
Reply With Quote
  #12  
Old 10-15-2017, 04:54:48 AM
armandh armandh is offline
Sponsor
 
Join Date: Aug 2006
Location: Suburban St. Louis, Missouri
Posts: 2,629
Thanks: 169
Thanked 625 Times in 503 Posts
Default Re: ONAN 6.5 NH-3CR/16004K Just starting out with this, first steps?

Quote:
Originally Posted by Runslow View Post
I'm not going to pick up new coils quite yet, I'll check the spark after I clean the points and see if that doesn't help a bit. I'll post an update here this afternoon or tomorrow with how that all goes, but thanks again for the advice offered!
in my case the points were electrically open in two places

where the moving point was crimped to the spring [crimp tightened]
where the adjustable point was crimped to the support [back soldered]

I eventually bought a new points/cap/plugs tune up kit.

overall electrically

there are two relays that, in parallel, supply 12 volts from the battery to the coil and fuel pump

the start relay only when cranking and the run relay [when running]
if the engine stops for any reason the exciter voltage which goes through a pull-down resistor to the run relay stops, and the relay opens.
if the oil pressure fails and the oil pressure switch opens the run relay opens. [the opposite of the idiot light switch type]
if the stop switch is depressed the relay end of the pull-down resistor is brought to 0 volts and the run relay opens.

the [field coil] exciter voltage also supplies the electric choke.
there is a diode that is between the exciter and battery sections.
this current charges the battery when running and offsets the drain of the fuel pump and coil,
but the diode prevents reverse flow when the engine stops.
starting
that [reverse] flow is accomplished by the cranking solenoid who's coil is in parallel with the start relay.
they operate only while cranking the engine when the exciter generator is used as a starter motor.

Last edited by armandh; 10-15-2017 at 06:03:29 AM.
Reply With Quote
The Following 3 Users Say Thank You to armandh For This Post:
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
Onan 6.5 NH-3CR /16004K Ing/run issue gator77318 Magnetos, Ignition Coils and Spark Plugs 1 04-21-2017 05:48:16 PM
Onan MCCK genset final install steps MN Laker Onan Generators 7 07-21-2016 02:18:41 PM
Onan 6.5 NH-3CR/16004K, SN E783358227 Jack D D Onan Generators 3 02-13-2016 06:53:02 PM
Onan 6.5NH-3CR/16004K on Natural Gas wa5dxp Onan Generators 4 11-30-2012 10:34:28 AM
First Steps to starting or restoring? Tips needed enginesilo Small Air Cooled Gasoline Engines 15 05-18-2008 08:55:45 PM


Use "Ctrl" mouse wheel to change screen size.
All times are GMT -4. The time now is 05:56:04 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