Very loud POP

[OceanTom]

Time to ask the pros_
What happens:
When my 2016 Ventana LE is turning onto a downward grade such that she rolls, there is (not every time) a super loud metallic pop that comes from under either the driver’s or passenger’s seat.

It actually sounds like a weld breaking, but a weld can’t break again and again- thank goodness. If you’re expecting it, you’ll actually feel it in your seat.

On the phone with FL shop and Newmar at the same time, the FL man suggested it sounded like one of the “fishplates” were slipping. He explained that the drawings call them “coupling plates”. They attach the frame/foundation of the Newmar coach construct to the Freightliner chassis rails. I was told in that call that no one welds to the Freightliner main chassis rails.

They retorqued everything in the chassis, but ran out of time to hunt for the coupling plates.

FL and Newmar both said they could not share a drawing showing the location of the plates. (Doesn’t that seem weak?)

Evidently the first plates are maybe hidden within the enclosure walls of the basement.

Does anyone have any experience opening the “walls” of the forward basement to expose the junction where the coach frame sits on the FL chassis?

Any thoughts from this experienced group is greatly appreciated.

Thanks,
Tom

[Dav L]

I would get a "chassis michrophone" which there are multiple michrophones that you can put in several proximate areas. You can then focus your listening to one of the mikes to isolate where the noise originates from by switching from mike to mike.

https://www.amazon.com/STEELMAN-0660...6449402&sr=8-3

I will use mine this weekend to isolate which wheel bearing is bad on my wife's escalade. A handy tool. In your case, the $100 tool might save hundreds in misdiagnosis. Pretty sure it's the passenger side wheel bearing. Bearing is $150 and labor is about two hours. So if it saves misdiagnosis, tool is paid for twice over.

Find a road where you can circle back and forth to duplicate the noise. Drive the same each time to get repeatable diagnosis.

Could be a bad ball joint. Or a driveshaft U joint (less odds). Or a cracked weld.

This is the type of thing that a good DIY'r can be better than a shop because proper diagnosis can take time. Time the owner doesn't want to pay a shop for. DIY'rs will spend the time to understand what's wrong. You can then point the mechanic to the exact area for them to further address (if you don't want to tackle the repair yourself depending on what you find).

[dbike199]

Originally Posted by Dav L

I would get a "chassis michrophone" which there are multiple michrophones that you can put in several proximate areas. You can then focus your listening to one of the mikes to isolate where the noise originates from by switching from mike to mike.

https://www.amazon.com/STEELMAN-0660...6449402&sr=8-3

I will use mine this weekend to isolate which wheel bearing is bad on my wife's escalade. A handy tool. In your case, the $100 tool might save hundreds in misdiagnosis. Pretty sure it's the passenger side wheel bearing. Bearing is $150 and labor is about two hours. So if it saves misdiagnosis, tool is paid for twice over.

Find a road where you can circle back and forth to duplicate the noise. Drive the same each time to get repeatable diagnosis.

Could be a bad ball joint. Or a driveshaft U joint (less odds). Or a cracked weld.

This is the type of thing that a good DIY'r can be better than a shop because proper diagnosis can take time. Time the owner doesn't want to pay a shop for. DIY'rs will spend the time to understand what's wrong. You can then point the mechanic to the exact area for them to further address (if you don't want to tackle the repair yourself depending on what you find).

I never knew there was such a tool, Amazing the knowledge on here. Cool tool too.
Thanks Dav L

[GMDLA]

Let me know if you figure the noise out. I have had it for 2 or 3 years and it has done the same thing as you described. Every year when I drop off at the local Freightliner for preventative maintenance I have them search for it. On the bright side I have not noticed any irregular tire wear or tracking problems. It is annoying, the wife just about jumps out of her seat every time it happens.

[Dutch Star Don]

Tom....sometimes, you just need to crawl under there and look for things amiss. A broken weld will have rust/dust around it. A shock ma have lost it's rubber grommet. Often sway bars brake a link or lose their rubber grommets.

Probably not your issue, but on my 2014 DS, it did the exact same thing....turns out of driveways it would clunk. I crawled under the front end and looked around. I found the five bolts holding the steering box to the frame were all loose. A couple had backed out a 1/2" . Clunk resolved.

[OceanTom]

Originally Posted by Dav L

I would get a "chassis michrophone" which there are multiple michrophones that you can put in several proximate areas. You can then focus your listening to one of the mikes to isolate where the noise originates from by switching from mike to mike.

https://www.amazon.com/STEELMAN-0660...6449402&sr=8-3

I will use mine this weekend to isolate which wheel bearing is bad on my wife's escalade. A handy tool. In your case, the $100 tool might save hundreds in misdiagnosis. Pretty sure it's the passenger side wheel bearing. Bearing is $150 and labor is about two hours. So if it saves misdiagnosis, tool is paid for twice over.

Find a road where you can circle back and forth to duplicate the noise. Drive the same each time to get repeatable diagnosis.

Could be a bad ball joint. Or a driveshaft U joint (less odds). Or a cracked weld.

This is the type of thing that a good DIY'r can be better than a shop because proper diagnosis can take time. Time the owner doesn't want to pay a shop for. DIY'rs will spend the time to understand what's wrong. You can then point the mechanic to the exact area for them to further address (if you don't want to tackle the repair yourself depending on what you find).

Very interesting tool Dav L.
Thanks!
Tom

[OceanTom]

Originally Posted by Dutch Star Don

Tom....sometimes, you just need to crawl under there and look for things amiss. A broken weld will have rust/dust around it. A shock ma have lost it's rubber grommet. Often sway bars brake a link or lose their rubber grommets.

Probably not your issue, but on my 2014 DS, it did the exact same thing....turns out of driveways it would clunk. I crawled under the front end and looked around. I found the five bolts holding the steering box to the frame were all loose. A couple had backed out a 1/2" . Clunk resolved.

Yes, I’ve looked and looked and I’ll undoubtedly keep at it.
I have a good rapport with the FL guys and they’ve given me their complete assurance that they’ve torqued every bolt and that all is safe. Glad you found you clunk before serious trouble.
Thanks,
Tom

[OceanTom]

Originally Posted by GMDLA

Let me know if you figure the noise out. I have had it for 2 or 3 years and it has done the same thing as you described. Every year when I drop off at the local Freightliner for preventative maintenance I have them search for it. On the bright side I have not noticed any irregular tire wear or tracking problems. It is annoying, the wife just about jumps out of her seat every time it happens.

Wow!
If I figure this out, I’ll definitely share the find.
Glad you’ve not had any noticeable problems.
FL guys assure me that it’s safe.
Thanks,
Tom

[Jgeib]

Does your coach have front drum brakes? If yes, could be the S cams. They can be very loud if they stick then release when breaking.

[OceanTom]

Originally Posted by Jgeib

Does your coach have front drum brakes? If yes, could be the S cams. They can be very loud if they stick then release when breaking.

The fronts are disks.
Thanks for thinking about my issue though!
Tom