Rocks in chassis rail

[westvic]

My PC has developed a rattle. It is a metalic sounding thing that sounds like loose washers being rattled somewhere and only at certain frequencies. I have checked everything I can think of. It has been up on a hoist for suspension check (and every thing else) and been through the local dealer for a service. Still nothing has been found. At least that rules out anything obvious.

I'm now strongly suspecting I've picked up a stone (or several) in the chassis rail. Anyone got some tips or advice on how to remove stones from in there?

thanks in advance

[old Jack]

Remove the end fitting off a garden hose and insert the hose into the access holes in the high points of the chassis in the wheel arches. Run the hose at full pressure and you will see a stream of sand, dirt, grit and rocks flow from the chassis drain holes.

I do this every time I clean the car after an off bitumen trip and are surprised at what collects inside the chassis rails.

I doubt this is your problem.

I would be also looking at the bash plate mounts, there are 6 in total, these crack even when the factory splash plates are fitted. When these mounts break you get a metallic rattle you can hear from the cabin.

OJ.

[Kingbrown]

I recall a few instances of a loose shroud surrounding the rear output shaft & seal of the transfer case. Might be worth a look to see if that shroud has come adrift..

Attached to the chassis rails just behind the front wheels there are two 'boxes' that I think are support points. These 'boxes' can easily catch a handful of gravel or rocks. You have to bend your wrist in a tight arc and reach into the top of the boxes to feel for debris.

The rear mudflaps are formed with a large void in the moulded upper part, just behind and directly above the mudflaps. . There's only a small drain hole for that void but plenty of rocks get trapped in there. Again, you need to have 'Inspector Gadget' hands to feel in that space.

[westvic]

Remove the end fitting off a garden hose and insert the hose into the access holes in the high points of the chassis in the wheel arches. Run the hose at full pressure and you will see a stream of sand, dirt, grit and rocks flow from the chassis drain holes.

I do this every time I clean the car after an off bitumen trip and are surprised at what collects inside the chassis rails.

I doubt this is your problem.

I would be also looking at the bash plate mounts, there are 6 in total, these crack even when the factory splash plates are fitted. When these mounts break you get a metallic rattle you can hear from the cabin.

OJ.

Thanks OJ. I have double checked all the mounts and all seem fine so not this. The stones I have already pulled out have often been larger than the drain holes in the chassis rails so I dont think a hose will fix this problem.

[westvic]

I recall a few instances of a loose shroud surrounding the rear output shaft & seal of the transfer case. Might be worth a look to see if that shroud has come adrift..

Attached to the chassis rails just behind the front wheels there are two 'boxes' that I think are support points. These 'boxes' can easily catch a handful of gravel or rocks. You have to bend your wrist in a tight arc and reach into the top of the boxes to feel for debris.

The rear mudflaps are formed with a large void in the moulded upper part, just behind and directly above the mudflaps. . There's only a small drain hole for that void but plenty of rocks get trapped in there. Again, you need to have 'Inspector Gadget' hands to feel in that space.

Thanks Kingbrown. Checked all these and problem still there. I had already cleaned out the boxes and there are 2 towards the rear as well. All had stones in them which were removed but problem still there.

I hadn't checked rear mudflaps though. The drivers side was empty but removed 30+ stones from the passenger side.

The hunt continues.

[westvic]

So....this bloody rattle is still there.

I can definitely confirm it isn't bash plates mounts. I have removed the plates and had the mounts over-welded.

Currently driving without bash plates (I'm waiting for Boos plates to arrive ) and the rattle is still there.

I still havent flushed the chassis rails though.

Any other suggestions??

cheers
Steve

[craka]

Is there any dust/stone cover over any of the uni joints on the prop shafts? I'm not familiar with challengers but had an old gen 2 pajero where the dust cover around a uni joint had come loose and making a hell of a racket.

[Alex86]

Does it happen when the vehicle is stationary at certain rev ranges?

I had a metallic rattle on my NL Escape at certain rpms (stationary and moving) that eventually got tracked down to the little metal label/plate (exhaust manufacturers brand label) which is tack-welded onto the exhaust pipe. One of the two tack welds had broken, and the metal plate vibrated.

Just another easy thing for you to look for.

[old Jack]

I also had the stone shield on the rear of the transfer case come loose and rub on the tailshaft intermittently, took me weeks to find it. When it was rubbing it made a screeching noise like a worn brake pad.

Towbar attachment bolts tight?

Exhaust not hitting on towbar?

Spare tyre up nice and tight, no rocks on top of the spare tyre?

OJ.

[westvic]

OK now I need a giant red faced emoji.

Working my way through all the suggestions above (which I had mostly already covered but thought I had better double check) and I think I have found it. Loose/dag end of spare tyre chain rattling inside the spare tyre steel rim.

I ended up being able to make it happen on demand. Aprox 1400rpm under light acceleration but not stationary. I rarely drive at that rpm which is why it seemed intermittent.

Anyway, it did serve as a great excuse to upgrade bashplates and mounts

thanks to everyone for replies
cheers
Steve