Onan 5,500 Generator

[Rich Biebel]

The generators cooling system is designed to flow air properly with the cover on and the access door in place. Removing the door defeats the design.

Biggest issue is underneath....Hot air exhaust on the right side can get drawn in where the cooler are intake area is......on the left...

The hot air area should be isolated or a metal shield built to direct the heat away from the intake side.

I see many very poor installs that lead to engine failures from this issue....

Trailers, motorhomes, commercial vehicles....

The best installs I see now have the hot air exhaust side totally enclosed underneath and the hot air directed to the side. Exhaust pipe is covered.
Painted Sheet metal custom designed for the vans.....

Dog groomer Ram Vans with the generator in a rear compartment on the floor.......Bottom cutout as needed....

Built by Onan of Indiana.....

Many builders never bother to read the install instructions about cooling....

It's an air cooled unit....If it takes in it's own hot air it will run so hot in summer you can't touch it...

I open my trailers generator compartment door but not if the sun is directing its heat right at the machine.

[SGSST109E]

The generator is mounted up in the front on the gooseneck. The exhaust pipe comes out the bottom and out to the side of the trailer. He also has the extension to direct the exhaust up past the roof.

[Rich Biebel]

Originally Posted by SGSST109E

The generator is mounted up in the front on the gooseneck. The exhaust pipe comes out the bottom and out to the side of the trailer. He also has the extension to direct the exhaust up past the roof.

The hot air is blown out the bottom same area as the exhaust pipe.

The cooler air is drawn in along the bottom at the front of the machine

If it's running you can feel the suction there and it can pull hot air in if there is nothing to stop it from going that way.

It's very strong suction and can pull paper or a rag up in there. It will suck a rag right out of your hand.....I've had it happen more than once just cleaning under a machine.

I saw one where birds nested up in there and blocked the cool air completely....It was a gooseneck trailer.....The machines engine failed from running to hot.....

Attach some sheet metal to help prevent the hot air from being pulled in......your machine will be a lot happier.....and live longer....I guarantee it...

[SGSST109E]

Thank you Rich

[KRatcliff]

Originally Posted by Rich Biebel

The generators cooling system is designed to flow air properly with the cover on and the access door in place. Removing the door defeats the design.

That is spot on. I had a plastic clip break on the bottom access plate to remove the oil filter on a QD 8,000. I removed this plate and put it on a shelf. The generator kept running hot until I got new plastic clips and replaced this little door.

[Rich Biebel]

All Onan RV generators are meant to run with all covers and doors ON.

Air cooled gas models as well as liquid cooled diesels.

The install manuals for all of them give all the info about air flow for cooling and proper hot air and exhaust venting.

The diesels have very strong air flow to blow cool air across the radiator and out. The suction area can get debris sucked in there on any of them....

I have had some guys tell me they removed the T-Stat on a diesel and it ran cooler.....I have not done that mostly because a diesel will build up a ton of carbon in the exhaust and if not run hot enough and under a good load they can wet stack as it's called......I've seen mufflers loaded with carbon.

They do go full rich under a heavy load and will pump out a lot of black smoke usually for a while until fully warm.....

[SGSST109E]

Rich - I got the trailer and the cover is black not green. Also the side access panel is missing. Are the panels readily available, new or used?

[Rich Biebel]

I can get any part for Onans. Just need model info off label. You can send me a picture to my cell phone. 201-317-5834

I save covers and doors from scrap machines but don’t have any black 5.5 doors. They have no latches like the green or white machines. You cannot run that machine without that access door in place as I’ve said for proper airflow.

I’m off work this week. Will be at Atco Friday afternoon thru Sunday. Racing the .90 races.

[SGSST109E]

Thanks, I'll the model tomorrow. Is there anything different about a black verse green
unit?

[Rich Biebel]

I think the black covered units were the RV versions. The green and now white units are called commercial mobile models. Really not much difference from RV to CM