Serious Generator Issues Con't

[kmuller]

Last week we had posted a blog concerning a failed generator exhaust. Well the saga has continued in a very serious way this week as we got into it further. Please go to the blog for a complete description and photos. http://www.zimmermancoach.com/?type=post&id=7 ("http://www.zimmermancoach.com/?type=post&id=7")

[Joe Cannarozzi]

Karl

We are really going to school on this one. I like everything you have suggested so far. All issues for us (86XL with 4500+hrs on the gen.) The white insulation the better lighting and exhaust plumbing and the monoxide sensor suggestions.

Good timing for us too, it's the off season for our bus for the next couple of months. We will be able to wait and move on your suggestions for all the above and have the luxury of time to do it as well.

I,m very curious as to what you find out about the flex pipe from the manufacturer in terms of the repeated in and out of the gen.

Our gen. compartment is so nasty I dont even want to post a pic. but we will when we get started. Ours will only slide out about 1/3 the way so its tuff to get a good look behind but as we disconnect the exhaust and the plumbing to the rad. and remove the rad. and the dividing wall between the two I think it is gonna open it up enough to do the job without having to completly remove the gen.

Great stuff- keep it coming.

[kmuller]

Joe - it is good you will be taking the time to go through you generator system. As long as it is working, many folks tend to check/change the oil and forget about the serious components. There are a lot of critical components in that compartment that deserve a serious inspection on a regular basis...regardless of whether it is 6 months or 20 years old.

We'll post additional info as we progress through the re-design/re-install.

[Joe Cannarozzi]

Not to get stuck on the lesser of your suggestions but there is something about a big WHITE cat motor that is seen in many larger boats and that excites me. Nothing cleaner. Nothing looks better and I just might go the extra mile and remove ours all the way to acheve this as well. Along with new insulation and a brighter light this will trully be the look that a Prevost should be sporting in the first place!

Still waiting for your results on the exhaust and insulation and if it can not be purchased locally we will be talking and placing an order.

I'm also curious as to the proper porcedure for pressure testing the exhaust. Ours goes all the way back and then up and out thruogh the roof at the rear. A couple of plugs, low to moderate air pressure, then wait for a pressure drop or get busy with a soapy water squirt bottle?

[kmuller]

Joe - yes, we would recommend about 3PSI. Obviously you have to disconnect from the manifold, plug both ends and pressurize. As you noted, you would see a drop on the pressure regulator, soapy water or an ultrasonic leak detector would help with locating and identifying the source. We are just about complete on our tubing and inulation research. We certainly have our favorite regarding insulation, but we really wanted to invest some time in product research on the exhaust tube, due the "cycle" issue of the tubing flexing everytime the genset slides in an out. As I said in a previous post, most flex exhaust tubing is designed for a one-time flex around an obstacle in the installation, not hundreds of cycles over many years. We should have the product research wrapped up shortly.

[Joe Cannarozzi]

Giving some time to concider issues before moving on them almost always helps. It occured to me a good remedy for prolonging the life of the flex pipe is to not slide the gen in and out accept when absolutly nessasary, and, that would include not sliding to do this inspection, instead, utilize the slide for a more limited purpose.

For our purposes the only time that sliding is really nessasary is to clean and or replace the insulation and do upgrades or to pull the gen. for major service that can not be done in place, such as things we are planning on doing presently.

Oil and filter changes can be done without sliding it out. Safty inspections as well!

We know all busses are engineered a little differently but for us we have 1 bay dedicated for both the gen. and the radiator. Concidering the issues you've raised with the flex pipe I'm thinking that after we do our improvements and changes, furure inspection will be done by removing the radiator and dividing wall to gain access to view instead of sliding out. This would eliminate the nessesity for replacement of that pipe as well as eliminating the expence and time of additional labor, along with the risk of damaging it.

This might seem like a lot of work but the rad. is held in with 2 bolts from underneath and the wall is removed with 6 easilly acessable wood screws. This process along with draining it shouldn't take an hour, not too much to ask on a say 2 year interval?

If this idea does become reality we can also greatly reduce the length of flex needed to say, just enough to isolate vibration instead of a large loop of it creating enough to slide out, making a lot less of an issue in the first place.

Sometimes less is better, right, help me out here. Where is this logic flawed in this circumstance?

I have already had to remove the rad. and blower behind to acess a valve related to the OTR A/C condedser in the next bay back and it was very easy and did not take long.

Unless your reaserch finds very positive results regarding that flex pipe I will give these thoughts/changes serious conciderations.

If I had to guess I would think that manufacturers are not going to be giving any guaranties in this application with repeated "exercize".

How is it that this thread is posted simotaniously in 2 different places? Magic?

[garyde]

It would seem to me that the Flexible Exhaust should be inspected every year when the Generator is normally serviced. If the Convertor can provide the resource, a new one should be ordered if necessary. Since there are few guidelines by the Feds regarding convertors on these issues, it would be best if the RVIA would step up and create some guidelines and maybe even an Alert notice through their subscriptions and Associated organizations.

[Gary & Peggy Stevens]

But Joe, isn't the fact that the Generators which are set up for ease of maintenance, and on special glide out rollers, and encased in so called Silent boxes, the WHOLE POINT? It seems a little futile to reinvente the wheel, by changing that all around, and not use the glide out to do things like check the gen sets. Surely one of the convertors ( or Mfgs. ) has noticed that the flex tubing is not acting properly when being pulled out with the gen set and willing to step up and fix the problem?

No PROBLEY NOT

Gary S

[Joe Cannarozzi]

Your right based on what I see on the Zimmerman blog, they deffinatly have not.

You are also correct about the original reason for a slide in the first place, ease of maintence. But it needed to be engineered correctly and the correct components used in the first place or it could use a change.

Concider this. When installing the pipe innitially on the gen. it is slid out. If the Man. says it is designed to be bent into a curve once only to couple a manifold to an exhaust pipe as you slide it in your already making that second adjustment.?

Again all our stuff is a little different and what I,m suggesting is that once I reinsulate, paint, replace that pipe and upgrade the lighting, in our application, it will not be nessesary to slide the gen. for anything other than a major mechanical repair. Unless Carl can reasure me that repeated flexing of the pipe due to sliding of the gen. is safe I will no longer be doing that especially since in our application it isint really nessesary in the first place.

I don't want to reinvent the wheel, just make sure the tire has air in it!

[Gary & Peggy Stevens]

I don't want to reinvent the wheel, just make sure the tire has air in it!

Joe: Touche' :D

[JIM CHALOUPKA]

A question that came to mind at the beginning of this topic and me not having a bus to look at and answer myself is:
Where is the exhaust ultimately expelled from the bus? What I am getting at here is if I were designing this system I would have the exhaust port be integral and affixed to the generator unit and move with it and line up with an exit port in the stainless door and not require a flexible connection at all.
Someone info please.
Why must the exit port and the movable generator be connected by a flex-pipe?
JIM

[garyde]

A question that came to mind at the beginning of this topic and me not having a bus to look at and answer myself is:
Where is the exhaust ultimately expelled from the bus? What I am getting at here is if I were designing this system I would have the exhaust port be integral and affixed to the generator unit and move with it and line up with an exit port in the stainless door and not require a flexible connection at all.
Someone info please.
Why must the exit port and the movable generator be connected by a flex-pipe?
JIM

One of the reasons for the Exhaust pipe is to exit it to the underside of the Coach and then to the back, or side of the coach. This reduces noise and limits exhaust fumes recirculating into a window.

[Jon Wehrenberg]

Jim,

If the generator rolls out for service a flex exhaust is required. If the generator is mounted in a fixed position the exhaust can be rigid.

The location of the end of the generator exhaust pipe is determined by the converter, and some terminate at the side, at the rear, or even up throught the roof. Gary is right about fumes, but another consideration is minimizing noise. Life really sucks when you have to park next to a motorhome with a noisy generator. It is as bad as being parked next to a cattle truck.

[JIM CHALOUPKA]

Jim,

If the generator rolls out for service a flex exhaust is required. If the generator is mounted in a fixed position the exhaust can be rigid.

The location of the end of the generator exhaust pipe is determined by the converter, and some terminate at the side, at the rear, or even up throught the roof. Gary is right about fumes, but another consideration is minimizing noise. Life really sucks when you have to park next to a motorhome with a noisy generator. It is as bad as being parked next to a cattle truck.

Jon, Thats an interesting analogy. What ever made you think of that? Am I missing some deep and underlying humor?
Thanks all for the ans. to my questions. I figured as much but try to get some baseline facts declared by others. When a system is designed and works most manufacturers tend to let it alone until some outside force comes along and forces a change, such as competition, government regs., safety, failure to function. You know if it aint broke don't fix it.
I don't think any of the converters intended for the exhaust to last a lifetime. Maintenance must be performed here as well as all those other places discussud on this forum.
My take is that there was great surprise that the gen. exhaust, was silently lurking in the underbelly waiting to poison and incinerate unknowing rvr,s. No one really thought about this as a maintenance issue.
It's just my nature to look for a different and better way to do things. I think if Karl doesn't come up with satispactory flex pipe replacements that there are other ways to achieve the desired results.
For one the gen. unit when slid out into the maintenance position would disconnect the exhaust, and when you slide it back in it would mate up with its other components attached to the undercairage. Another would be to have rigid tubing move with the gen. slide and exiting under the bus. Even with everything made from rigid tubing it would not last forever.
So what has occured here may be nothing more than the discovery of a maintenance issue. Check the flexpipe often and replace as needed.
My observation of the forum is that most involved are excessive compulsive about the bus (that's a good thing) and that there is a lot of nit picking of details. " A chain is only as strong as its weakest link". I think it's to the point of, now the weakest link ,(one of which there will always be) is being chased.:eek: :eek:
God why do I run off like this. :D JIM

JPJ is influencing me?

[Jon Wehrenberg]

Just remember Jim, if you choose to have a "breakaway" exhaust on roll out generators that becomes a highly probable leak point. It also precludes running the generator when it is rolled out, such as when you wish to do a manual start.

On our coach the generator box is ventilated with a fan, and it is pulling air through it so pressure is low. I'm not suggesting it eliminates the need to check the flex hose exhaust, but it does help to avoid some danger. Consistent with that we also have CO detectors in the house.

You need to own one of these coaches to understand the reliability and service life of the systems and components. There are flaws and we often discuss them, but in the overall scheme of things the coaches are very well thought out and extremely reliable.

[gmcbuffalo]

My Beaver 92 conversion has the generator on a slide out. The exhaust system is a sliding ridged tube. One fixed tube with the generator tube sliding inside the that one. The only flaw is as Jon states the seal when the generator is all the way in closed. There is a asbestos seal, but if it is not tight I have a leak. I really feel I need a better sealing system. Maybe a removable cuff that clamps on around the opening of the larger fixed tube and sliding tube.
GregM

[JIM CHALOUPKA]

My Beaver 92 conversion has the generator on a slide out. The exhaust system is a sliding ridged tube. One fixed tube with the generator tube sliding inside the that one. The only flaw is as Jon states the seal when the generator is all the way in closed. There is a asbestos seal, but if it is not tight I have a leak. I really feel I need a better sealing system. Maybe a removable cuff that clamps on around the opening of the larger fixed tube and sliding tube.
GregM

Yes sir Greg, That's what I envisioned. Maybe have the penetration length longer. That would tend to reduce the pressure at the joint. You could taper the socket tube and the penetrating tube so when they came together the joint size along the taper would get smaller and finally an the moment of engagement become tight and a spring loaded asbestos gasketed flange at the end joint. ;) JIM

[kmuller]

Gentlemen - A little more info on the generator exhaust. The flex tubing that was in the coach was the typical auto parts store variety. It was spiral wrapped, which means it had a spiral seam it's entire length, and intended for a one time flex. Much of the seam had failed. Not the best choice. We have located a very high temp rated flex hose, extruded to shape (not spiral wrapped) and tested to 50,000 cycles. As we suspected, there is an ASTM specification that is applicable and highly desirable. We have custom spec'd the product, our pressure test requirements, and the type of couplings we want, to the manufacturer and expect delivery of the product shortly. Once we have the product in our hands, I will report further.

As Jon mentioned, this coach also has an "exhaust fan" which is intended to help with the heat of the compartment. The fan blades were covered in fine soot. We noted there was no indicator which would tell the owner if this fan was operating or not. It's position does not allow for a visual inspection while the generator is running. We will re-design that as well.

[Joe Cannarozzi]

"And tested to 50000 cycles." That has to be one heck of a way better product. About 50000 times better!

I would really hope, EXPECT, all these high end, high priced converters to already be doing such things? Especially concidering the ramifications of a failure here. Ya think vision could be blurred by all the paint and polish?

Once again, WHAT A GREAT CLUB.