excessive air coming out from under genset

[Dunnpe]

This past weekend I was driving slowly along a dirt road in a campgroud with genset (5.5 Onan) on to use the AC unit. I noticed a cloud of dirt being kicked up from under the left rear of the coach. I stopped and looked and it was coming directly out of the bottom of the genset. After we stopped I looked closer in that area and it seemed to be coming somewhere from in front of the muffler and did not see anything that would accomodate that much air. Does anyone have any idea what it could be. There is exhaust coming out of the tailpipe also. It doesn't sount like an exhaust leak or overly loud, just alot a hot air coming outs from somewhere in that vicinity.

[Dunnpe]

This past weekend I was driving slowly along a dirt road in a campgroud with genset (5.5 Onan) on to use the AC unit. I noticed a cloud of dirt being kicked up from under the left rear of the coach. I stopped and looked and it was coming directly out of the bottom of the genset. After we stopped I looked closer in that area and it seemed to be coming somewhere from in front of the muffler and did not see anything that would accomodate that much air. Does anyone have any idea what it could be. There is exhaust coming out of the tailpipe also. It doesn't sount like an exhaust leak or overly loud, just alot a hot air coming outs from somewhere in that vicinity.

[ChasA]

I think it may be just air from the fan on the genset. My 4KW onan is air cooled. I got under it once when it was running and it does push a lot of air out under there.

[RCtime]

I had the 5.5 onan on my last coach. A really nice genset.
It is air cooled and just doing what comes naturally for it. If you didn't have all the air movement you would fry it real fast.

[AFChap]

<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">with genset (5.5 Onan) on to use the AC unit </div></BLOCKQUOTE>
If you have basement air, it also will be pushing lots of hot air straight down while running (normally on passenger side rear). The DW always turns our ac unit off when we enter RV parks/etc with dusty dirt roads. That not only saves getting a lot of dust on the toad, it also keeps a lot of dust out of the basement ac box & motors.

[Izzyblueye]

It could be either or both the gen or A/C output of exhaust air (not combustion exhaust). Mine has a lot of air coming out of the A/C right rear area, when it is operating.

[Chief]

The air discharge is probably a design feature in an air cooled genset. The cooling fan forces air, via cowling and/or ducts, over the generator and engine to keep it from overheating. Old Volkswagens and some airplane engines used the same system.

[Hikerdogs]

The generator will put out quite a volume of air to keep it cool. If you have a dual tube muffler the spark arrestor unit on the top section of the muffler has a plug that might be missing. Page 21 of the owners manual describes the location and procedure for inspection.

Here's a link to the index page for generator owners manuals on the Cummins Onan site: http://www.cumminsonan.com/rv/support/manuals

[Pubtym]

Missing item here...to be added...is the fact that road dust primarily from rear wheels is recirculating back up into air filter of GEN Set...rapidly fouling it up. I learned that after inspecting my Gen Set air filter after running Gen Set as I drove along somewhat dusty road. It was really dirty with same dust.

If I see dusty road conditions with Gen Set operating, now I'll shut down Gen Set and A/C until back on non dusty surface.

Added: I always carry a new/spare Gen Set air filter...just in case..replaceing them early makes all gen Set factors happy...and that in turn tickles the electrical items supported by Gen Set.

[Dunnpe]

Thanks to all who have responded. I am sure glad it is normal. I did and will from now on turn the genset and AC unit off during runs on dirt roads to eliminate and excess dirt flying and causing premature problems. This is a superb forum.