Add Generator Intake Vent

[Hgrace56]

My Onan 4000 is behind the front wheel and on hot days overheats when driving. Of course I really only want to use it on hot days yo jerk the house cool while driving.
The Fleetwood dealer recommend an intake bent be added.
Anyone done this? Anyone have an aesthetically pleasing vent recommendation?

[BFlinn181]

If you search the forum, others have posted issues with overheating and adding or modifying a vent in line with the generator intake. It doesn't look like it would be too hard to add a vent in the door, then build up a gasketed box to ensure all the air comes from the outside. As I recall, some folks were having issues with heated air or exhaust being sucked into the generator intake.

[powercat_ras]

I found that directing the air cooling exhaust farther out the bottom of the 4000 using a HVAC piece solved the problem for me. It seemed like much of the hot air would go right back to the intake air vent with the OEM configuration.

[Hgrace56]

Originally Posted by powercat_ras

I found that directing the air cooling exhaust farther out the bottom of the 4000 using a HVAC piece solved the problem for me. It seemed like much of the hot air would go right back to the intake air vent with the OEM configuration.

This looks like a great first effort.
Makes sense at speed cooling air would just swirl back up.
Did you screw it in?
Can you recall the rectangular size?

[powercat_ras]

> Did you screw it in?

Yes, with self-drilling sheet metal screws. Then went all around it with metal tape to get a good seal.

> Rectangular size?

12" x 4" Rectangle x 7" Round outlet. Modified the 12" x 4" to allow for the engine exhaust pipe and to right angle flange it so I would have something to screw thru into the generator base.

All the air blown around the generator to air cool it exhausts thru a rectangular hole in the bottom. In my RV the bottom of the Onan 4000 generator is well above the bottom of the side wall so a lot of the hot air was staying between the side wall and the generator and getting sucked right back into the generator air intake . Doing this mod alone lowered the exhaust point to right above the top of the side wall and it blows it straight down below the side of the RV to the ground now.

My intake air temperature dropped by 20 degrees F at the air inlet grille after this mod and is now about outside air ambient temp even after the generator has heated up. I have had no problems with the generator shutdown due to overheat since.

[Hgrace56]

Gonna try this tonight

[BFlinn181]

While moving, the extension should work great. Sitting still, I wonder. The hot air is diverted down, but as we all know, hot air rises. What's to stop it from being drawn in by the intake? You could open the cover over the generator compartment, but they you'll have to deal with extra noise. I've seen grills a bit larger than the intake opening in the generator side cut into the compartment door, then a large foam gasket used to seal the space between the door and the generator input.

[Kahoona]

I did that

http://www.irv2.com/forums/f84/4k-on...on-253670.html

[Dtwallace]

Originally Posted by Hgrace56

This looks like a great first effort.
Makes sense at speed cooling air would just swirl back up.
Did you screw it in?
Can you recall the rectangular size?

I think that duct work is a great idea, you could even add an elbow to it directing the hot air our to the side if you wanted.

Straight down, don't park over dry grass and run it unattended. I had one of my toy haulers burn the grass, luckily no fire, with no mods, just the heat coming straight down under normal operation.

DTW

[BFlinn181]

Originally Posted by Kahoona

I did that

http://www.irv2.com/forums/f84/4k-on...on-253670.html

Nice mod, I like the reuse of the Sea Ray louvers!

[Hgrace56]

Did this.
Feels like 10 times the air flow now.
I'm sure this will keep the temp down.
I'll see on Wednesday on my way to Santa Barbara.

[Hgrace56]

Well.
Tried it on the road today .
Shut down in less than an hour.
Try vent next week

[Jpcoleman]

Not sure that has enough of a "Venturi" effect. It might work better to have a wide exhaust port perhaps angled such that a rectangular opening faces down with a slight angle such that air passing by could be used to "suck" the air through.

[Waiter21]

I installed vents in the cover. Sucks hot air out

Generator Compartment vents – 2001 Coachmen Mirada 300QB

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