Bighorn / Onan question

divedreamer

Active Member
Finally bought my Onan 5500 HGJAB and unboxed it. 33 1/2" versus the 32" hole. It looks as if I need to modify the box or disassemble the front door to get it in. Frustrated and scared to measure the bolt pattern as I can't see how to get the bolts in anyway. Anyone have this dillema? Suggestions? I also want to install an auto start and auto transfer. Anyone know anything about that or experience?
Thanks
Brad
 

divedreamer

Active Member
I am sure not the corner to corner measurement is 4 inches longer than the width of the opening and it is deep enough front to back on the genny to prevent me from spinning it into place. I think I may be able to make it fit if I butcher the edge of the wall (of the box) and bend it out of the way and then bend it back into place and seal it with silicone. To do this I will have to remove the frame and move it approximately 5 inches toward the left side of the trailer. There would be about an inch of clearance on either side of the generator.
Brad
 

danemayer

Well-known member
Maybe a call to Heartland Customer Service would help. Perhaps they can connect you with someone who knows what needs to be done, or point you to a local shop with experience installing generators. 877-262-8032.


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divedreamer

Active Member
It's actually the frame and yes I could but it won't give me all the room I need. I think I need to cut the wall of the isolation box and bend it enough to achieve the room I need. Then bend it back and re-seal it with silicone. It's all a mystery as to how the dimensions aren't right. Happy Thanksgiving!
 

rick_debbie_gallant

Well-known member
Remove door frame. Slice down through the front skin. Make frame for piece cut out. Install generator. Cover bottom of front skin from side to side with diamond plate 1/8 or 1/4 inch thick. What ya think?


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porthole

Retired
I also want to install an auto start and auto transfer. Anyone know anything about that or experience?

Transfer switch is not aa big deal. Metal box about 6x6x4. Wires in from genney and shore power - wires out to panel. Moving and bending the wires is the hardest part.

Remote start is an option from Onan
 

PUG

Pug
You will undoubtedly have to put it in, take it out, put it in, etc. etc. taking measurements, marking holes to bolt it down, etc. I had a Onan in my Cyclone that was factory installed and was a very nice installation and worked great. My new unit had gen prep so I just installed a Champion. The Champion is considerably smaller than your Onan but it was still quite a job. Here is kind of a format how I installed it and what I had to do to make it all work:

1. First set in to locate exactly where I wanted it with room considerations for other items such as my freezer.
2. Location considered for intake cooling air, exhaust venting, heat considerations.
3. Marked areas for intake cooling, exhaust exiting, and bolt down holes for generator.
4. Drilled holes for intake cooling , cut 4 inch hole in floor for exhaust exiting. On mine I had to build an exhaust manifold coming out of the generator into a 90 degree elbow 2 inch exhaust pipe that goes down through the hole in the floor and is then connected to another 90 degree elbow. The exhaust was the hardest of all of the installation. The manifold had to be welded up to make the right angle down through the floor with out touching the sides of the hole. I did not want the exhaust pipe contacting the sides of the hole for vibration concerns etc.
5. Drilled holes to bolt gen to floor.
6. The choke was on a side end of the gen that made it difficult to get my hand into to operate. I purchased a choke cable kit and fabricated a couple of mounts to make it work and installed it on the face panel of the gen.
7. Set gen in, bolted it down, had the exhaust manifold preinstalled and attached the first 90 degree angle pipe with exhaust clamp.
8. Attached 2nd 90 degree exhaust pipe and ran 7 ft straight exhaust pipe out underneath trl using exhaust pipe hangers that have rubber mounts to help on vibration. Attached a chrome end to exhaust pipe to dress it up. I ran the exhaust pipe under to the door side of the trl as I did not want the exhaust to come up under my bedroom slide.
9. I wired up a 30 amp plug to plug into the gen and wired the other end into the gen prep wiring box.
10. The gen I bought is a single phase (110 volt only) that runs up to 30 amps 3500 running wattage 4000 watt startup. My needs are met with this smaller generator where I do not do a lot of dry camping. This unit still lets me run one AC, microwave, and battery charger or other combinations of power usage. Champion generators are fairly inexpensive to purchase with different combinations of features. They have a very good reputation and are being sold through many major retailers. I got mine through Cabelos on sale.

If I were to do it again I would possible to to a little larger unit with dual 110,220 circuits and remote wireless electric start. I still have to go outside to open the front bay door up for cooling so having to go up there to start isn't that big of a deal.

11. Time to complete two days, would have taken less but cussing and screw ups added time. Cost of gen $325, exhaust pipe, elbows about $125, wiring $50. misc $25. I have a wire feed welder, oxy-actylene setup and metal chop saw, grinders etc.

12. I am adding an additional fire extinguisher and carbon monoxide detector to the front bay.


Good luck
 

divedreamer

Active Member
Thanks PUG. I started tonight. I took out the mounting frame as it was obviously in the wrong location. I tried to bolt up the genny. What a pain. The holes did not match. I have to make one end oblong to fit genny mounting bolts (about a 3/8" short end to end. Once that fits I can layout for mounting the frame in the isolation box. It is going to be tight. Then I have to figure what to do to get the genny into the isolation box It's about an inch and a half to narrow at the opening. Thank God my grandson taught me a little patience (even though it wasn't evident while trying to get the mounting bolts mated up on the frame tonight lol). I have to go through the box to get the wires to the gen wire box. I don't know yet where the auto transfer switch is. I am assuming that is where I will want to mount the auto start box. Thanks
Brad
 

divedreamer

Active Member
Thanks Gallants. Something to consider. I had not thought of doing anything on the exterior. Still leaning toward a mod on the isolation box and then caulking everything air tight again.
Brad
 

rick_debbie_gallant

Well-known member
Brad, I think I would rather deal with the thin skin on the trailer in cutting it rather than the skin on the generator. With the diamond plate u would end up with a much stronger front of your rig. Just my opinion.
Rick


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