Community Forums

jedova · 09-01-2018, 09:31 PM

I've tried searching on welding and I'm either not using the correct words or there aren't any past threads. The generator exhaust pipe on my 2007 36FDTS has a slight kink, does not reach the edge of the coach, and is too close to my driver's tire so I'm going to have a new exhaust pipe made. I have three questions: 1) Is disconnecting the coach and chassis negative battery cables sufficient to protect my electronics (I'm thinking Vansco(s) here) if we are welding on the generator exhaust pipe? 2) does anyone know whether the generator exhaust pipe should protrude to the outside of the edge of the coach or should it end before the outside edge of the coach (so it's not sticking out)? 3) should the end of the exhaust pipe have a downturn to it? Currently mine does not. I'm scheduled for this repair on Wednesday (Sept. 5th), so I would appreciate your feedback before then.

Jeep401 · 09-01-2018, 10:19 PM

I'm not sure what's safe practice for the welding.
My pipe sticks out past the side of the coach which I believe is best, you don't want the exhaust gasses under the coach. I think the turn down is up to you, but mine is straight.

Soppy · 09-02-2018, 04:49 AM

Should be no problem welding on the exhaust. Make sure the coach has no shore connections (power , water , sewer, cable, etc). Place the ground cable on the exhaust pipe as close to the welding area as possible. Make sure the pipe is cleaned to get a proper connection. Then weld away . No need to disconnect the batteries.

c_oneil · 09-02-2018, 05:13 AM

I don't understand why someone would weld on your generator pipe while it is bolted to the coach. It is far easier to remove the old pipe, fabricate and weld a new pipe while standing at a work bench rather than laying on your back under the coach.

Old Scout · 09-02-2018, 06:38 AM

What Carter said--unless Onan changed it in later years [doubt it], two bolts hold the exhaust pipe to the flange on the muffler?????? Now, if the flange on the muffler is bent or broken, that is a different issue. Even then the muffle can be removed for the work--good time to do a thorough spark arrestor inspection...Think you need a second opinion before the 5th.

jedova · 09-02-2018, 07:17 AM

Quote:

Originally Posted by Old Scout

What Carter said--unless Onan changed it in later years [doubt it], two bolts hold the exhaust pipe to the flange on the muffler?????? Now, if the flange on the muffler is bent or broken, that is a different issue. Even then the muffle can be removed for the work--good time to do a thorough spark arrestor inspection...Think you need a second opinion before the 5th.

Thanks to you and Carter for the suggestion; I think we will take that approach. My exhaust repairman is young guy with no experience on motorhomes but has the equipment for bending and building exhaust systems.

Jeep401 · 09-02-2018, 07:26 AM

Very good point!!!

lazybyrd · 09-02-2018, 08:26 AM

Carter is spot on.
I have had a rattle in the front of my coach that I traced down to the genny exhaust hitting a brace. There was excessive travel on the exhaust due to a woreout support rubber. I have had it off a couple of times and removal required minimal effort. The tip does have a turndown and sticks out beyond the plane of the coach wall about 3”.

TMan59 · 09-02-2018, 08:44 AM

I would also remove the exhaust.
I personally would not weld on the coach unless there is no option.
There seems to be the idea that welding, and a Vansco failure shortly after have something in common.
Whether true or not, why risk it.

lazybyrd · 09-02-2018, 08:56 AM

Agreed.
We applied that rule to all welding on equipment in my past life. If we were not able to remove the parts in need of repair we removed control, ignition and annunciation equipment from the machine before welding and then moved the ground lead for the welder as close to the work as possible. These practices seemed to cut down on ghosts and goblins after the welding was performed.
Hope all have a good holiday!

Janet and Todd · 09-02-2018, 09:33 AM

I'm pretty sure there is a placard on Vansco equipped coaches that warns not to weld on this frame. Either that or it's in the owner's manual. It's always a good idea to check the signature tag on posts to ascertain if the responder has an Alpine. A well meaning response from a non Alpiner could cost thousands in fried electronics.

TMan59 · 09-02-2018, 09:35 AM

Quote:

Originally Posted by Janet and Todd

I'm pretty sure there is a placard on Vansco equipped coaches that warns not to weld on this frame. Either that or it's in the owner's manual. It's always a good idea to check the signature tag on posts to ascertain if the responder has an Alpine. A well meaning response from a non Alpiner could cost thousands in fried electronics.

I wonder if that’s where the perception not to weld on the coach comes from?

twinboat · 09-02-2018, 10:04 AM

I've been welding on construction machines for years and they all now, since computer engine controls, caution that the computer be disconnected while welding.

With multiple computer operated items, now days, removing the battery cables may be the best protection.

In most cases the welding is isolated to the parts needing it, but there are times when the welding ground could fall off and find another ground point. I've seen, and had it happen to me, where we would lay down the rod holder on a grounded surface causing a arc.

We needed to be careful not to let the ground conduct thru bearings or bushings. An arc, jumping thru the grease gap of a bearing, can cause it to fail soon after.

Janet and Todd · 09-02-2018, 10:34 AM

Here is the placard but it's for the Transmission, not the Vansco. It's in the battery bay. So you have the tranny module, the Wabco module, ECM for the Cummins, the Vansco and maybe the HWH etc. Forewarned is forearmed. Danger Will Robinson and all that jazz.