87 to 89 onan exhaust

[Bruce]

This question is for Bill, John(birds first), Rob Britton and any other Onan owner. While on the rough roads in Mexico I lost my exhaust sytem. $100 muffler was less than 2 years old!! I noticed a write up by Rob Britton on another forum showing how he replaced the flex pipe. My Gennie does not have any flex pipe. The exhaust pipes are 1.25 black iron pipe (elbows and nipples). The muffler has a threaded inlet and takes a 1.25 inch tailpipe. My exhaust pipe broke by one of the elbows. I dont know if it was from the stress due to a lack of flexibility or maybe the exhaust gasses ate away at the pipe. Exhaust tubing can take flex but not iron pipe. I have ordered another muffler but want to make sure this problem does not reoccur. So the question for othewr owners is: Does your Onan have a flex pipe in the exhaust sytem? If so where is this placed? Thanks

[Bill Pape]

Hey Bruce,

This is on my repair list , but it is still usable, so we need your input after repair and replacement.

The flex section of pipe is in the rear behind the gennie, it can not be seen except looking up from under the bus. Reach behind the valve cover and find the two exhaust manifold bolts, probably 9/16 and hopefully they are not too rusted and will easily break loose. (working blind on these bolts).
There is also an exhaust manifold gasket. Remove the entire exhaust pipe & muffler system and start over.
This is another over design by BB, But it did last over 20 yrs.
I would try replacing with an inexpensive car muffler, all new pipes & hangers.
Should be an easy replacement in Mexico or an auto parts store.
There are several 90 degree turns and short pipes.

[Bruce]

HI Bill:

MIne had no flex. Just 1.25 nipples and elbows. My tailpipe is 1.25 inches. Those bolts are are murder to undo without dropping the gennie. They are metric and use a 17 mm wrench. You cannot use a socket as there is no room and the base of the flange gets in the way as well. I had removed my bolts when I had the gennie out. I cleaned the threads so they would be easy to remove in the future. Rob Britton adpated a stainless flex and it looks good. Maybe mine broke due to no flex pipe??? I am sticking with the Onan muffler as it will probably be quieter than a generic unit. My tailpipe is just a straight piece of pipe and exits at the rear. Rob's picture looks like his might exit to the side or is offset?? I am sure mine was original so BB may have tried a few different systems.

[Bill Pape]

Rob B.,

Can you post a picture???

[Robert Britton]

My Onan exhaust has a 90 just after the manifold that directs the exhaust toward the ground, after the 90 there is a short pipe about four inches long. At this point the flex pipe is attached with muffler clamps. A few more bends to direct it to the rear and side a bit and exits out the rear (see photos).

Mine had a flex pipe that I had repaired a few times until I finally replaced it with the one in the photo, available at any muffler shop. I had the muffler shop weld on short piece of pipe the same diameter as the pipe coming of the 90, then he flared the ends so it would slide over existing pipe and secure with muffler clamps.

I was able to do this job from under the coach, generator left in place.

[Bill Pape]

Robert, Thank You,


That is the same as our 88 FC, I need to face this issue some day soon.

[Bruce]

" I had the muffler shop weld on short piece of pipe the same diameter as the pipe coming of the 90, then he flared the ends so it would slide over existing pipe and secure with muffler clamps"

Hi Robert:

Was that pipe coming out of the 90 iron pipe or a piece of exhaust tubing?

Thanks

[Robert Britton]

Originally Posted by Bruce

" I had the muffler shop weld on short piece of pipe the same diameter as the pipe coming of the 90, then he flared the ends so it would slide over existing pipe and secure with muffler clamps"

Hi Robert:

Was that pipe coming out of the 90 iron pipe or a piece of exhaust tubing?

Thanks

Iron pipe,the only exhaust tubing are the short piece I added on either side of the new flex joint. Both ends of that tubing were flared to fit over the iron pipe.

[Bruce]

Thanks Robert.

[birds_first]

Bruce & Others: Today I discovered another issue with the Onan while changing my oil. On the bottom below the oil filter there is a 3/8" brass spigot, and it feeds through the bottom of the generator shelf for the oil drain. Inside the spigot there is a brass & a steel washer with a rubber seat, my rubber seat has deteriorated so when I shut off the spigot I had a serious oil leak through the drain. So I removed the brass spigot and replaced it with a 1.5" 3/8" steel nipple and a 3/8" elbow with a 2.5" nipple through the shelf with a 3/8 screw cap under the shelf. Now I get to search for a new brass spigot. Any suggestions?