Trying to diagnose a loud rattle coming from the floorboard

No experience here.
Possible motor mount failure?
What happens with hard acceleration in lower gears?
Pat

I had such a rattle...was an exhaust hanger. Try to replicate the experience...run it up...and then climb under and touch every item with a long-ish metal bar..like a screw driver.


Gary Haupt

My thoughts, it takes 30 minutes to appear gives the impression it's heat related. I would start right from where the exhaust pipes leave the engine compartment and inspect each connecting point,especially the heat shields.
Catalytic converters will rattle once they warm up IF the ceramics have broken loose.(rare).

My 08 Jeep had such a problem, drove me crazy, only after it warmed up. Believed it was converter. Took it to a muffler shop, where the pipes crossed over there was a metal skid plate, it had a broken weld. Why only when it was warm was a stumper even for the muffler expert.

My guess is it's the shields. Get a mirror and a flashlight and get under there OR get a shop to inspect on a lift.That's money well spent.

On my 2008 Fleetwood 31' with the E-450 engine I also had a bad rattle at highway speeds. It was a loose plastic engine shroud on the bottom of the engine. I took it off and the rattle stopped. One day I will put the engine shroud back on with new plastic clips.

I've had the exact rattle for years in my 2005 E450 motorhome chassis. It started after we had owned it for a couple of years maybe with 15K to 20k miles on it - just like the OP.

EVERYTHING has been checked by me and others down there underneath ... all shields, mounts, brackets, torque converter cover, etc..

I'm convinced that it's probably some of the guts of the catalytic converter loose/broken and rattling at certain speeds and/or heat conditions. If catalytic converters didn't cost so much, I'd just replace it to get rid of the occasional racket. However, it seems like in the last year or so that the rattling has maybe lessened a bit and is not so irritating. (By the way, alternatively, is there some kind of a resonater in the exhaust line that could have loose parts rattling around inside of it?)

I'm very interested in what the OP discovers it is if they pursue it all the way, including installation of a new cat converter.

pnichols wrote:
I've had the exact rattle for years in my 2005 E450 motorhome chassis. It started after we had owned it for a couple of years maybe with 15K to 20k miles on it - just like the OP.

EVERYTHING has been checked by me and others down there underneath ... all shields, mounts, brackets, torque converter cover, etc..

I'm convinced that it's probably some of the guts of the catalytic converter loose/broken and rattling at certain speeds and/or heat conditions. If catalytic converters didn't cost so much, I'd just replace it to get rid of the occasional racket. However, it seems like in the last year or so that the rattling has maybe lessened a bit and is not so irritating. (By the way, alternatively, is there some kind of a resonater in the exhaust line that could have loose parts rattling around inside of it?)

I'm very interested in what the OP discovers it is if they pursue it all the way, including installation of a new cat converter.

Also there are baffles inside the muffler that get rusted and can come loose. I would tap on the muffler, cat and resonator if you have one and see if it rattles.

Depending on your states vehicle testing....one can have the cat converter removed. They are a in constant state of deterioration.

Gary Haupt

I don't know if this the same thing but my MH sounded like symbols. It was the shields , I bought "S" strips, cut and drilled holes pushed them all around the edge of the shields, screwed self taping screws in and that was it. Hope his helps.

I wonder it it's the infamous E350/E450 serpentine belt "rattle"?

This has been discussed a lot in the Ford owners forums. I believe the solution has something to do with an additional, or different, idler pulley between installed at a certain place in the belt's path so as to better support the belt at certain engine speeds.

All of my delayed rattles have been exhaust related. My Jeep, motorhome and diesel pickup. Inspect very closely, there is metal touching metal somewhere. My GMC it was the bracket that holds the exhaust as it leaves the manifold, my jeep a crossover bracket connected to the cat and my "C" a exhaust shield bracket under the shield and difficult to see.

I found my rattle on my C by driving home after smog inspection with the dog house off, kind of tough to do and only a few miles but the rattle noise with and without the dog house sounds like two totally different areas.
To check your motor mount, raise hood, apply parking brake and gently accelerate and see if the engine tilts or lifts. You can have someone watch from a safe distance or record with your phone. Hold foot brake as well, just a touch on the accelerator will do it.