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Onan 4.0CCK round style generator head


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  #21  
Old 12-15-2015, 02:52:39 PM
gnucklehead gnucklehead is offline
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Default Re: onan 4.0cck round style generator head

If you want to put it into a box/shed/shelter (does it have vacuflow?, the ad is gone), there are some RV installation details in the T-012 manual (T-012 Onan Installation of GenSets for RVs -Tech Bulletin (10-1976).pdf), on the twinslan site. 4.0CCK requires minimum inlet of 100 square inches of _unrestricted_ airflow. I'm building a dog coop for a pair of gensets, had to look it up recently.

Have to agree on the big facet fuel pumps, never seen a bad one (that wasn't physically damaged), usually have a bayonet endcap with a fuel filter in there, easy to clean. I use 2/0 battery cabling on round heads
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  #22  
Old 12-15-2015, 04:15:47 PM
turtmaster turtmaster is online now
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Default Re: onan 4.0cck round style generator head

yes it has vacuflow cooling
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  #23  
Old 12-15-2015, 07:14:19 PM
len k len k is online now
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Default Re: onan 4.0cck round style generator head

Quote:
Originally Posted by vanman View Post
THREE HUNDRED AMPS?!? To crank a little tiny engine?? I've heard that these Onan's somehow have inefficient cranking motors but that's crazy! ......
It's not an external starter like cars have. It's exciter cranked. They use the gen exciter windings to crank the engine directly 1:1, so there is no torque advantage from gear-reduction of large ring gear. It is an inefficient setup, it's a design compromise to eliminate external starter. Maybe they figured RVs have huge battery banks anyways for inverter power. Later RV gens like NHE used external starters.

A chev 305 V8 engine takes 200-300 amps. I dont have a CCK or NH but I've read here they do take alot of amps, maybe >300.

Quote:
Originally Posted by vanman View Post
Cranking slowly won't hurt anything. It's when the cranking stops completely for too long that's a problem......
True, but if bat gets old or cold your that much closer to not cranking and burn if you don't stop the current. And that's something your likely not going to want to do when it's 0 degs, wind is howling, and you need to heat the house.
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  #24  
Old 09-18-2016, 03:06:12 PM
turtmaster turtmaster is online now
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Default Re: onan 4.0cck round style, speed droop too much under load

i have replaced the governer spring, cleaned the carb, adjusted the timing, new plugs.
under about a 3500w load the speed droops too much to about 56 hz, it is at 62-63hz no load, if i manually move the throttle lever by hand i can get it run at the correct speed,
the govener sensitivity is at the max position, if i adjust the vacuum booster and the govener so i get the correct speed undel load, at no load i end up with about 140v.
the vacuum booster spring and the booster diaphram are both good.

my other 4.0cck spec r, i can load up to 5500w and still get 110v with the no load volts at about 130v

i don't know what to try next, i am out of ideas.
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  #25  
Old 09-18-2016, 04:01:08 PM
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Jim McIntyre Jim McIntyre is offline
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Default Re: onan 4.0cck round style generator head

Could the linkage length be wrong? With the engine shut off, is the throttle FULLY open? It should be...
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  #26  
Old 03-12-2017, 11:07:03 PM
turtmaster turtmaster is online now
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Default Re: onan 4.0cck round style generator head

new problem, i am only getting 17.4 volts to the choke heater coil, instead of the ~30v needed, even when measured at the start solenoid, and directly at the dc brushes. i cleaned the ac slip rings and the dc commutator with scotchbrite pads stapled to a piece of wood. and the brushes are free in the holders. so the voltage is low coming out of the exciter windings.
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  #27  
Old 03-13-2017, 06:49:03 AM
Kevin K Kevin K is offline
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Default Re: Onan 4.0CCK round style generator head

If you post the full model number maybe we can get you a wiring diagram. Is the generator end a square head or round head? Pictures would help. The exciter voltage is applied to the choke. The first thing I would check is the engine speed. Make sure it is running at 1800RPM. What is the AC voltage? If the engine speed is low, the exciter voltage will be low, and the output voltage will also be low.
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Old 03-13-2017, 07:08:57 AM
MBB MBB is offline
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Default Re: Onan 4.0CCK round style generator head

As Kevin mentioned check low engine speed. Check it's running on both cylinders. They run very well on one. (No power).
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  #29  
Old 03-13-2017, 10:09:41 AM
turtmaster turtmaster is online now
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Default Re: Onan 4.0CCK round style generator head

https://www.smokstak.com/forum/showthread.php?t=160983 pictures at the link 4.0cck-1r/111p
it's running on both cylinders, running at about 60hz, can handle a 4000w load
also just replaced the fuel pump with a facet posi-flow 60300 bolted right up. from aircraft spruce.

ac out is 125-130 no load
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  #30  
Old 03-15-2017, 12:25:11 AM
turtmaster turtmaster is online now
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Default Re: Onan 4.0CCK round style generator head

Hello? MBB?, kevin k?
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  #31  
Old 03-15-2017, 06:37:19 PM
Kevin K Kevin K is offline
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Default Re: Onan 4.0CCK round style generator head

Let's review the current situation:
Your CCK is running at 1800RPM, approximately 60Hz.
The AC voltage output is in the area of 125 volts no load.
The CCK can handle a full 4,000 watts load, with the AC voltage output in the area of 110 volts at full load.

I looked in the database, but I can't find a production order for 4.0cck-1r/111p. Our database is not perfect, and there are occasionally models that do not show up. I did find 4.0CCK-1R/11191P, is this your number?

With an exciter voltage of approximately 17 volts, there may be nothing wrong with your generator. The exciter voltage is proportional to engine speed. If the exciter voltage was approximately 1/2 of normal, there is no way the generator could produce full output. The Onan regulation scheme on these generators is to magnetically saturate the pole pieces so that the output voltage is proportional to engine speed.

Onan does not seem to specify exciter voltage on the round head CCK's. The square head UN generator ends, including the CCK's, run at approximately 30 VDC. The MCCK's, both round and square head, run at approximately 30VDC except for Spec H which runs at 110VDC.

The 2.5LK exciter voltage runs at 17VDC, except for the "utility truck" model which runs at 15VDC.

I'm not sure about the round head CCK's. I think some run at lower voltages than 30VDC, but I'm not sure which ones, and I'm not sure of the voltage. I have a 4.0CCK-3CR and a 5.0CCK-1R round head CCK's, but they are sitting up on blocks in the basement and I can't easily get them out until summer.

Maybe someone with a round head 4CCK can measure the exciter voltage.

I would say that if your 4CCK is running at 1800RPM (60Hz), the no load voltage is correct, and it can carry a full load the exciter voltage is OK.
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  #32  
Old 03-16-2017, 12:24:05 AM
turtmaster turtmaster is online now
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Default Re: Onan 4.0CCK round style generator head

Kevin, yes 11191p is correct, I thought that the number was wrong, but I could not check it as the gen is at my dad's house, I can't find off-hand what the number for the bimetallic choke spring that I used, it was the only number I could find in several of the cck parts manuals, in several of the part manuals, the number for the choke coil spring was BLANK in the spot for it, from the one on the twinslan site. The smaller several turn coil is the new one, the older larger 15+ turn coil in the hand is the old coil, was SPRUNG, but the new coil is the only cck choke coil spring part I could find. The reason I was asking about the choke's excited voltage being low, is that was taking FOREVER for the choke to open, compared to my other spec r 4.0 square head cck that I converted from the "sisson" type choke to the "Onan" type choke,and carb that I got from spenserpearson's bf that he was parting out. And also compared to my 5.0 bga, it was taking FOREVER for the choke to open, like 5 minutes for it to fully open. So that's when I checked the excited voltage, and found it was only 17.5v.

When you look at the picture of the choke spring in the choke housing, the old choke spring left marks on the back of the choke housing that look like a spring.


Could the commutator brush holder assembly "clock/clocking" position have something to do with the low exciter voltage?

I am almost tempted to order a cheap $10 5-10a dc-dc boost converter from the Asian country that starts with the letter "C" from eBay for a quick fix to get the choke to open faster.
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  #33  
Old 03-16-2017, 01:55:15 PM
Kevin K Kevin K is offline
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Default Re: Onan 4.0CCK round style generator head

Quote:
Originally Posted by turtmaster View Post
Could the commutator brush holder assembly "clock/clocking" position have something to do with the low exciter voltage?
You don't want to mess with that adjustment if the generator is working correctly. Finding the neutral point has been discussed somewhere here in the past. Changing the adjustment can lead to excessive sparking on the commutator brushes.

I looked at the choke heater in a few of my generators, as well as searching through some parts manuals. The parts manuals all reference the same number 153-0017 (153-A17). One LK, a BFA, and a square head CCK had the small spring. My round head 5CCK had the larger spring. I think the springs work the same, the smaller version is the newer replacement.

There is a difference in the choke heater. The generators with the 17 volt exciter (2.5LK, 5CCK round head) use part number 153-0113, which measures approximately 11 ohms. The generators with a 28 to 30 volt exciter (5CCK square head, 4BFA) use part number 153-0114, which measures approximately 28 ohms.

Check your heater to see which version you have. For your 17 volt exciter you need 153-0113. Using the 153-0014 would cause the choke to open very slowly.

We both learned something here. There is a difference in the exciter voltage between the round head and square head CCK models. There are two different choke heater elements available for use with the lower 17 volt and higher 28 volt exciters.
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  #34  
Old 03-16-2017, 09:21:58 PM
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Default Re: Onan 4.0CCK round style generator head

I Called my dad and had him measure the resistance of the choke heater and it is 10 ohms, the part number on the choke heater is 153-113 in the old part numbering system, so the new system part number is 153-0113 so I guess we now know that round head cck generator heads have 17v exciter choke heater voltage instead of the un heads 30v exciter voltage.
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  #35  
Old 03-17-2017, 06:57:13 AM
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Default Re: Onan 4.0CCK round style generator head

So then, why the slow choke opening? The 2.5LK I checked, made in 1987, has the small spring and the 153-0113 heater. Because it is a "Utility Truck" model, the exciter voltage is 15 volts, lower than the standard 17 volts, Yet the choke works well.

Did you set the initial choke opening based on ambient temperature? The choke should not be fully closed unless the ambient temperature is below 50 degrees or so. The Master Engine Service Manual has a chart with a guide to setting the initial opening.
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  #36  
Old 03-17-2017, 02:51:24 PM
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Default Re: Onan 4.0CCK round style generator head

Kevin, I had the furnace in the garage set to 58° F when I was assembling and adjusting the choke, and yes I looked up the choke adjustment info from the twinslan site that I had previously downloaded, and adjusting it to what it said. then I took the gen outside to test run it, the only thing I can otherwise think of why it was taking so long to open up is that was only about 25° F outside at the time of the generator test run.

And I had let the generator cold soak outside for a little while.
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  #37  
Old 03-17-2017, 03:54:58 PM
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Default Re: Onan 4.0CCK round style generator head

OK, I admit I never started my CCK's at that low of a temperature. I guess that's what I can expect. The manuals mention adjusting the choke for different temperature conditions. We just let it warm up for five minutes or so.

The newer sets such as the Emerald have a vacuum pull-off to open the choke a bit when the engine has started.
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