Serious Generator Issues Con’t

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Last week, we published a blog about a malfunctioning generator exhaust. This week, the situation has escalated significantly as we delved deeper into the issue. For a full overview and photos, please check out the blog.

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Karl,

We are really learning a lot from this situation. I appreciate all the suggestions you’ve made so far, especially regarding the white insulation, improved lighting, exhaust plumbing, and carbon monoxide sensor recommendations—all relevant for our 86XL with over 4500 hours on the generator.

The timing couldn’t be better, as our bus is in the off-season for the next couple of months. This gives us the opportunity to implement your suggestions without any rush.

I’m also very interested to hear what you discover about the flex pipe from the manufacturer concerning the repeated in-and-out motion of the generator.

Our generator compartment is in such a messy state that I hesitate to share a photo, but we will once we start working on it. The generator will only slide out about a third of the way, making it difficult to see behind it. However, as we disconnect the exhaust and plumbing to the radiator, and remove the radiator and the dividing wall between the two, I believe it will create enough space to complete the job without having to completely remove the generator.

Great information—keep it coming!

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Joe,

It’s great to hear that you’re dedicating time to inspect your generator system. Many people only focus on checking or changing the oil as long as the generator is running, but there are several critical components in that compartment that require thorough inspection regularly, whether the system is 6 months or 20 years old.

We’ll share more information as we move forward with the redesign and reinstallation.

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I don’t mean to dwell on the less critical suggestions, but there’s something truly exciting about having a big white Cat engine, which is commonly found in many larger boats. Nothing is cleaner or looks better, and I might even go the extra mile to completely remove ours to achieve this look. Combined with new insulation and brighter lighting, this would give our Prevost the appearance it deserves!

I’m still waiting for your findings on the exhaust and insulation. If we can’t source them locally, we’ll definitely be in touch to place an order.

I’m also curious about the correct procedure for pressure testing the exhaust. Ours runs all the way back and then goes up and out through the roof at the rear. Would a couple of plugs, some low to moderate air pressure, and then waiting for a pressure drop be the way to go? Or should I use a soapy water squirt bottle to check for leaks?

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Joe,

Yes, we recommend using about 3 PSI for the pressure test. You’ll need to disconnect the exhaust from the manifold, plug both ends, and then pressurize it. As you mentioned, you’ll see a drop on the pressure regulator, and using soapy water or an ultrasonic leak detector will help pinpoint the source of any leaks.

We’re almost done with our research on tubing and insulation. While we have a preferred choice for insulation, we wanted to dedicate some time to product research on the exhaust tubing, especially considering the issue of flexing every time the generator slides in and out. As I mentioned in a previous message, most flex exhaust tubing is designed for a single flex around an obstacle, not for enduring hundreds of cycles over many years. We should have our product research finalized soon.

 

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Taking time to consider issues before acting is always beneficial. I realized that a good way to extend the life of the flex pipe is to limit sliding the generator in and out to only when absolutely necessary. This includes not sliding it out just for inspections; instead, we can use the slide for more specific purposes.

For us, the only times sliding is truly necessary are for cleaning or replacing the insulation, making upgrades, or pulling the generator for major servicing that can’t be done in place, like the tasks we’re currently planning.

Oil and filter changes, as well as safety inspections, can be performed without sliding the generator out.

We know that every bus has its own engineering quirks, but in our case, we have one bay dedicated to both the generator and the radiator. Given the concerns you’ve raised about the flex pipe, I’m considering that after making our improvements, future inspections could be done by removing the radiator and the dividing wall for access, instead of sliding the generator out. This approach would eliminate the need to replace the flex pipe, saving time, expense, and the risk of damage.

This may sound like a lot of work, but the radiator is secured with just two bolts underneath, and the wall can be removed with six easily accessible wood screws. The entire process, including draining it, shouldn’t take more than an hour, which seems reasonable for a two-year interval.

If this idea comes to fruition, we could also significantly reduce the length of the flex pipe needed—just enough to isolate vibration rather than having a large loop that complicates things.

Sometimes less is more, right? Help me out here—where does this logic fall short in this situation?

I’ve previously removed the radiator and blower to access a valve related to the OTR A/C condenser in the bay behind, and it was straightforward and quick.

Unless your research yields very promising results regarding that flex pipe, I’ll seriously consider these ideas and changes.

I suspect that manufacturers may not provide guarantees for applications involving repeated “exercise.”

By the way, how is it possible that this thread is posted simultaneously in two different places? Is it magic?

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It seems to me that the flexible exhaust should be inspected annually during the generator’s regular service. If the converter can provide the necessary resources, a new one should be ordered if needed. Since there are limited federal guidelines regarding converters on these matters, it would be beneficial for the RVIA to take the initiative and establish some guidelines. Additionally, they could issue an alert notice through their subscriptions and associated organizations.

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But Joe, isn’t the whole point that generators are designed for easy maintenance, set up with glide-out rollers and encased in so-called silent boxes? It seems somewhat pointless to completely change that setup and not utilize the glide-out feature for tasks like checking the generator. Surely one of the converters (or manufacturers) has noticed that the flex tubing isn’t functioning properly when being pulled out with the generator and would be willing to address the issue.

But probably not.

Gary S.

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But Joe, isn’t the main purpose that generators are designed for easy maintenance, equipped with glide-out rollers, and housed in so-called silent boxes? It feels a bit futile to overhaul that system and not take advantage of the glide-out feature for checking the generator. Surely one of the converters (or manufacturers) has recognized that the flex tubing isn’t working properly when the generator is pulled out and would be ready to tackle the issue.

But probably not.

Gary S.

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I’m not looking to reinvent the wheel; I just want to ensure the tire has enough air in it!a

Joe: Touché!

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A question that came to mind at the start of this discussion, especially since I don’t have a bus to examine, is: where does the exhaust ultimately exit the bus? What I’m getting at is that if I were designing this system, I would have the exhaust port integrated with the generator unit, allowing it to move with the generator and align with an exit port in the stainless steel door, thus eliminating the need for a flexible connection entirely.

Can someone provide more information on this? Why must the exit port and the movable generator be connected by a flex pipe?

Jim

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A question that came to mind at the start of this discussion, especially since I don’t have a bus to examine, is: where does the exhaust ultimately exit the bus? What I’m getting at is that if I were designing this system, I would have the exhaust port integrated with the generator unit, allowing it to move with the generator and align with an exit port in the stainless steel door, thus eliminating the need for a flexible connection entirely.

Can someone provide more information on this? Why must the exit port and the movable generator be connected by a flex pipe?

Jim

One of the reasons for the exhaust pipe design is to route it to the underside of the coach and then out to the back or side. This approach helps reduce noise and minimizes the risk of exhaust fumes recirculating into windows.

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Jim,

If the generator rolls out for service, a flex exhaust is necessary. However, if the generator is mounted in a fixed position, a rigid exhaust can be used.

The placement of the generator exhaust pipe’s end is determined by the converter, with some terminating at the side, the rear, or even venting through the roof. Gary is correct about managing fumes, but noise reduction is another key consideration. It’s quite unpleasant to park next to a motorhome with a loud generator; it can be just as disruptive as being next to a cattle truck.

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Jim,

If the generator rolls out for service, a flex exhaust is necessary. However, if the generator is mounted in a fixed position, a rigid exhaust can be used.

The placement of the generator exhaust pipe’s end is determined by the converter, with some terminating at the side, the rear, or even venting through the roof. Gary is correct about managing fumes, but noise reduction is another key consideration. It’s quite unpleasant to park next to a motorhome with a loud generator; it can be just as disruptive as being next to a cattle truck.

Jon,

That’s an interesting analogy! What made you think of that? Am I missing some deeper humor here?

Thanks to everyone for answering my questions. I figured as much, but I wanted to establish some baseline facts from others. When a system is designed and functions well, most manufacturers tend to leave it alone until an external force—like competition, government regulations, safety concerns, or functional failures—pushes for a change. You know the saying: if it ain’t broke, don’t fix it.

I don’t think any of the converters intended for the exhaust to last a lifetime. Maintenance needs to be performed here, just like in all the other areas discussed on this forum.

My impression is that there was a significant surprise when the generator exhaust was found lurking under the vehicle, posing a risk to unsuspecting RVers. This aspect was likely overlooked as a maintenance issue.

It’s just my nature to seek different and better ways to do things. If Karl doesn’t come up with satisfactory flex pipe replacements, I believe there are alternative solutions to achieve the desired results.

For instance, the generator could disconnect the exhaust when it slides out into the maintenance position, and then reattach itself to its components under the carriage when slid back in. Another option could be to use rigid tubing that moves with the generator slide, exiting under the bus. However, even rigid tubing wouldn’t last forever.

What we might be witnessing here is simply the discovery of a maintenance issue: check the flex pipe regularly and replace it as needed.

I’ve noticed that many people on this forum are quite meticulous about their buses (which is a good thing!), but there seems to be a lot of nitpicking over details. A chain is only as strong as its weakest link, and it feels like we’re now chasing that weakest link.

God, why do I tend to ramble like this? Is JPJ influencing me?

Jim

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My 1992 Beaver conversion has the generator mounted on a slide-out. The exhaust system consists of a sliding rigid tube, with one fixed tube and the generator tube sliding inside it. The only flaw, as Jon mentioned, is the seal when the generator is fully closed. There’s an asbestos seal, but if it’s not tight, I end up with a leak. I really think I need a better sealing system—perhaps a removable cuff that clamps around the opening of the larger fixed tube and the sliding tube.

Greg M.

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