Generator Exhaust Leak?

[Jim Stoltz]

My generator is underneath my couch toward the front of the motorhome. When camping at the Pocono Raceway last year, it was clear that not all the exhaust was going up the Venturi. The guy next to me said that it is not uncommon for an Onan generator of that vintage to leak exhaust. Trouble is that he wasn't reall specific as to where.

Over the weekend, I was exercising the genny with some electric heaters and my CO alarm went off! So, time to find the leak. Are there "common" leak spots on these things? Mine is a 6500.

[david craft]

with all the heat on an air cooled motor...the bolts get rusted and annealed.  just follow the exhaust.  make sure the muffler assm. is well supported and exits the side of the coach.  seal the doghouse well and window above the genset should seal well as well..

[Jim Stoltz]

I'll have to do that (follow the exhaust). The muffler is in good shape. It has a pretty short run out from under the rig. There is a pipe bolted to the manifold that could be suspect, but it looks to be a real pain to get at.

If I had to guess, I'd think the doghouse could also be part of the problem. It was just kind of sitting there - not bolted down. Over the weekend I installed it properly. 

The window above the genny is in good shape and seems to seal properly (as far as RV windows are concerned, anyway).

[david craft]

by doghouse I was thinking the genny doghouse but anyplace under the coach that could leak inside.  point being, even if the pipe exits the side of the coach, there is still a lot of exhaust present.  if there is a CO cloud under the coach and a roof vent is open, then it would seem that CO could be drawn into the coach by the low pressure internally created by airflow over the vent.

[Jim Stoltz]

That makes sense. Just performed the same test. Over a 2 hour period no CO alarm. But it smells like exhaust in here. I'll have to check out the genny doghouse as well.

Overall I'm pleased with it. Ran both furnaces and a 1500 watt electric heater and it got nice and warm pretty quick despite the near-single digit temps (F). The floor is super cold, but that's to be expected.

[david craft]

i agree totally with the unburnt gas odor. lets not forget that there are oxides of nitrogen and sulfer, most likely others too that are pungent as well...

[Jim Stoltz]

It smells like it's running rich. Not sure how to tune the thing, but it starts immediately and makes electricity so I'm not going to mess with it other than to repair the exhaust leak.

[david craft]

my local onan guy says its almost cheaper to put a new carb than rebuild, they are so cheap...

[Jim Stoltz]

Probably. It looks like it has an electric choke that is pulling off like it should. I'll deal with it in the Spring. First (planned) "dry camping" trip isn't until early June. It's at the Pocono Raceway and they pack the RVs in there. I don't want to offend with exhaust fumes.

[david craft]

standard carb stuff applies.  1/8' gap on choke at 70 degrees.  carb top inverted should yield float base parallel to parting flange or top.  more specs to be found online because each sentence in this comment should be followed by " I think".   I do know that RPM is critical because it determines cycles per second on power output.  BTW...I thought fumes were part and parcel of the racetrack experience...hehe

[Jim Stoltz]

I have the manual for the generator (the original owner of my RV kept EVERYTHING). The section that discusses tuning (particularly in checking for cycles and voltage) makes my head swim. But I'll check it out eventually.

Yes there are fumes at the racetrack, but it's alcohol (fuel and beverages). My neigbors didn't like the unburned fuel exhaust smell so I keep the generator usage to a minimum last time out.