Replacing Generator

Jimhartman · January 31, 2020, 02:53 PM

My 6.5kw '87 Onan on the '87 chieftain looks like it might be dead. Generator mechanic is pulling it but believes the windings are likely done.

If I have to replace this thing, are there any options to an ONAN for onboard? I want to use both AC units while driving in the summer.

30 amp system with a separate 20amp fuse that powers the rear AC.

I cant be the only person who has tried to figure this out, and I am not interested in buying a new Onan for the old girl.

ClydesdaleKevin · January 31, 2020, 07:22 PM

Keep your eyes open on Craigslist. I see Onan generators all the time for sale there. Other good used generators to watch for on Craigslist are Kohler (outstanding gennies), Honda (rare, but well made and water cooled), and even Gernerac (they don't make RV gennies anymore, but parts are still available).

What exactly did the generator mechanic say was wrong with your generator? The windings rarely go bad. How many hours are on it? What is it doing exactly when you start it?

Kev

Rickf1985 · February 01, 2020, 10:17 AM

You are going to need more than 30 amps to run two AC units. The generator you had was 50 amp. It can be done and it has been written up on here a few times. I have not done it on mine because I have not put the 6.5K genny in mine yet but when I do I will be rewiring so that the rear AC unit will be on a separate breaker.

Froggy1936 · February 01, 2020, 01:32 PM

Tip, 90% of generators failures are the voltage regulator, Caused by Generator shutting down under a load. The regulator tries to keep supplying full output as the RPM,s die off Frank

Jimhartman · February 02, 2020, 12:22 PM

Took it to a Cummins repair shop. He is dropping it this week but believes the windings are shot. It was putting out erratic voltage (180- 60) the last time I fired it up to exercise it. Then it wouldnÃ¢â,¬â,,¢t turn over after I shut it down.

I am optimistic it will be fixable, but preparing for bad news.

Wondering if I canÃ¢â,¬â,,¢t just stuff a harbour freight predator in there and call it done.

I am already wired with a 30amp to run the coach and one A/C and a seperate 20amp for the rear.

BamBam · February 02, 2020, 04:05 PM

Quote from: Jimhartman on February 02, 2020, 12:22 PM

Wondering if I canÃ¢â,¬â,,¢t just stuff a harbour freight predator in there and call it done.

I don't see why not? Other people have done the same, don't know why you can't? Do some web searches on the subject. Good Luck

Froggy1936 · February 02, 2020, 07:12 PM

That is what I did see the projects section Worked perfectly ! Frank

Jimhartman · February 10, 2020, 11:12 AM

Frank--found your post.

How did you work the fuel supply? I dont think I can fit an entire harbour freight generator into the spot on my 87 cheiftain. Even if it does, I wont have access to feed the fuel tank.

Did you install a fuel pump of some sort? If so, how did you rig it up?

Froggy1936 · February 10, 2020, 04:47 PM

Hi I had to remove the Harbor Freight Generator from its framework I was replacing a Honda Generator (you cannot see any difference in them) The Honda Framework fits in the opening without the Fuel tank, I have a small pulsating 12V electric fuel pump hooked to my Main fuel tank ,The unit was built for a generator i dont know if it ever had one But the fuel line was there ! I made up an exhaust system I had to add a 110V fan in the back of the compartment plugged into the generator And have the door open when running or it will overheat and shut down Maybe just because its new ??Frank

Jimhartman · February 11, 2020, 09:18 AM

Thats along the same lines as I was thinking. How are you powering your 12v pump---i.e, how do you tell it when to turn on and off? Manual on and off seems like an accident waiting to happen. Any idea what fuel pressure you are running on that pump? Did you do anything about the fuel return line? I see most of the Predators these days have one going back to the fuel tank.

I was thinking of adding a 12v radiator fan (powered by the generator) to the vented generator door to pull in fresh air when its running. I primarily use the generator to power the AC units during the summer when we are travelling, so I need a solution that works when moving.

Pain is an excellent teacher, but i prefer to learn by other peoples pain!

Froggy1936 · February 11, 2020, 02:37 PM

I have a manual switch with a pilot light to the outside I do not know the pressure , But if i remember correctly the instructions said 3-4 Lbs . When done using the generator i make sure all loads are off.(failure to do so will eat the voltage regulator , or if equipped blow the fuse or breaker. ) Then i turn off the pump and let the Carb run dry Never had a carb problem in 20 yrs . no return line .
I also have a radiator fan on the door for use when traveling , Also can block the door open with awning support ! Also i added styrofoam insulation to compartment! Frank

Surfinhurf · May 15, 2020, 12:41 PM

Quote from: Jimhartman on February 02, 2020, 12:22 PM

Wondering if I canÃ¢â,¬â,,¢t just stuff a harbour freight predator in there and call it done.

I would be worried about heat and the tank of gas sitting on top.
Onan did ALOT of work on engineering a system to get air in and out of the area. (Vacuflow)
I would replace it with a comparable ONAN 6.5, engineered to operate in the tiny space .
They run at 1800 RPMs and the crankcase holds 3.5 quarts of oil so they run cooler and quiet(lifetime)
A HF genny will be 3600 RPMs and the crankcase only holds 1qt. (Disposable)
A Good, running, generating ONAN 6.5 can be found for under $500.