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Onan Generators

Onan 7.5 JB 3CR/2442T Added to the Fleet


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  #21  
Old 03-17-2018, 08:52:41 PM
Leon N. Leon N. is offline
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Default Re: Onan 7.5 JB 3CR/2442T Added to the Fleet

Yes, I agree. I think Johnny C sand blasts his parts and then re paints them. Make sure you refer to the correct wiring diagram when going over your control box. I hesitate to tell anyone what to do especially if it is not a JB like yours and mine which are pretty much identical. I feel very confident that I know my JB sufficiently to respond to most questions. If I am not sure, I will let you know that.
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Old 03-18-2018, 06:29:07 AM
EICBob EICBob is offline
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Default Re: Onan 7.5 JB 3CR/2442T Added to the Fleet

Thanks Leon...
Between you and the rest of the great people here on the STAK, I am pretty confident I will be able to breathe new life into this unit.
I am not sure I want to do a repaint on it but I do want to clean up those nasty relays and make sure they work.
The open frame relay, really looks bad....are most of those relays the same? I saw on ebay a control box for a JC 12.5 for sale and the pictures show a pretty clean open frame relay.

-Bob
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  #23  
Old 03-18-2018, 07:58:30 AM
Leon N. Leon N. is offline
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Default Re: Onan 7.5 JB 3CR/2442T Added to the Fleet

When I had finished refurbishing my JB I installed it in a new 8x12 woo framed shed. Everything was working fine until one day a no start condition occurred. What I found was mice got into the control box and made a royal mess. I cleaned it out best I could. I never got around to removing all components and getting that mice excrement completely removed. IN fact there are still a couple of chewed wires. I am embarrassed to tell you this.

Long story short, not so much now but for a long time I had an occassional no start due to the dirty contacts on that exposed ignition start relay. What ai do is spray the relay contacts with a contact cleaner and off it goes. Have not had a no start condition now for oh maybe a couple of years.

If I can get my ambition back, coupled with some good weather, I may just refab my control box. In fact I have purchased new wiring, terminal strips and wire terminating lugs just in case I decide to tackle it.

So, I think you may be able to salvage that open construction relay. One thing you have to watch is make sure all terminal screw down lugs make good electrical contact.
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  #24  
Old 03-18-2018, 08:01:41 AM
Max Thompson Max Thompson is offline
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Default Re: Onan 7.5 JB 3CR/2442T Added to the Fleet

Quote:
Originally Posted by EICBob View Post
The open frame relay, really looks bad....are most of those relays the same? -Bob
No, some are 6 volt coils and some are 12-V.

Many of us have been changing the open relays over to plug in style sealed relays. In the linked album are before and after pictures of one I did recently. https://www.smokstak.com/forum/album...pictureid=9756

This link has the part numbers I used and a crude diagram of how the new relay wires up. Note the example is from a YD control box which differs slightly from the box you have. There are many choices for relays, these just happen to be what I used. https://www.smokstak.com/forum/album.php?albumid=1428
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Old 03-18-2018, 08:10:03 AM
JohnnyC JohnnyC is offline
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Default Re: Onan 7.5 JB 3CR/2442T Added to the Fleet

Quote:
Originally Posted by EICBob View Post
Thank you Leon...
I will look there to see what I have to work with. I need to ask JohnnyC how he is able to clean up all those crappy looking parts and make them look and work like new.
I will need to pull out the 2 relays from the control box and clean/verify and replace if needed. Looks like some wiring will need to pe replaced too.

-Bob
Hi Bob,
99% of the rust and paint is removed using the simple tools shown in the picture below. Before any paint and rust removal I gunk down the parts to remove oil and dirt. The end result is new looking parts.

I had a sand blaster in the past and it did a good job in some cases, but I did not have a cabinet blaster so any sand blasting made a mess.

*** As a word of caution, use the appropriate protection when using the tools shown in the picture below. If the brush on the angle grinder catches your cloths while in operation it will mess you up big time. I wear a leather jacket and eye protection. When using the bench grinder, wear good eye protection since little parts sometimes decides to sail through the air when you lease expect it.

JohnnyC
New Jersey
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  #26  
Old 03-18-2018, 08:42:24 AM
EICBob EICBob is offline
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Default Re: Onan 7.5 JB 3CR/2442T Added to the Fleet

Thank you JohnnyC....
I have in the past used your choice of tools....they do indeed work very well and command RESPECT!
I watched the progress on you charge current resistor work. Excellent work BTW!
What did you use to clean up the resistor? I used to use an aerosol can of electronic rework cleaner in the past to clean up controls and switches, but sadly due to EPA regs that product is no longer available. So I am looking for an alternative product that will clean up things like that resistor, open frame relays and snap switches with out destroying them further.

I am in awe at your prowess with the spray gun!
-Bob
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  #27  
Old 03-20-2018, 08:38:26 AM
EICBob EICBob is offline
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Default Re: Onan 7.5 JB 3CR/2442T Added to the Fleet

Tested the starter yesterday, unit cranks over and makes about 40psi on the oil pressure gauge.
Oil looks clean and the filter appears to be ok. I will change the oil and filter before actually starting the engine.
One of the Stak members came up with the air cleaner assembly, so the flow of replacement parts has started.

My plan is to convert this over to propane operation. Should I leave the fuel pump and sediment bowl in place or is it better to remove it and block off the engine block with a plate?

-Bob
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  #28  
Old 03-20-2018, 08:56:29 AM
Wayne 440 Wayne 440 is offline
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Default Re: Onan 7.5 JB 3CR/2442T Added to the Fleet

Remove it. Running a mechanical pump dry is not good for it.
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Old 03-20-2018, 09:10:21 AM
consolenut consolenut is offline
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Default Re: Onan 7.5 JB 3CR/2442T Added to the Fleet

Bob are you going to be switching the carb out to a gaseous carb? Or do you have a tri- fuel in place now. If you are not using the gasoline carb i am interested in it.
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  #30  
Old 03-20-2018, 10:40:03 AM
EICBob EICBob is offline
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Default Re: Onan 7.5 JB 3CR/2442T Added to the Fleet

Thanks Wayne....
I was thinking that it was better to pull the pump, but figured I would ask

Consolenut....
The unit has a Tri-Fuel carb installed, so all I need is to get the demand regulator, the shutoff solenoid and a hose to go to the carb. There is a rubber plug currently capping off the port for the gaseous supply.
I may borrow those parts from my 4CCK to do the preliminary testing.
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