Thread: Weird rattle coming from underneath

For months I have had a noise that sounds like something touching as engine /fan rotates.
Starts at about 2000 rpm and ceases at 2400, and I cannot hear it when in top (auto).
Sounds more like a "clattering" that more happen if say a blade was touching something as it rotated.
Have checked all over nothing loose, nothing touching, no loose heat shields.
From drivers seat sound appears to be coming from left of centre nearer the firewall rather than up near engine front

If I place my hand on the high/low range selector I can sort of feel a vibration that matches the noise am hearing.
Vibration through H/L selector stops when noise stops.
Cannot see anything loose on H/L linkages ect (but bit hard to get close up to). I do have a scope if there is some place I should be looking.

I was thinking something to do with torque convertor/drive plate (from the sound of it), but it has gone on so long I doubt it is in that department.
Has near new engine mounts, but original gear box mount. Do gear box mounts perhaps add noises /vibrations?

Just an annoying noise, but I'd like it gone if anybody can suggest what to look at.

Originally Posted by Graeme

Is the heat shield above the muffler loose?

My heat shield above muffler is loose (just sits off the body on its mount bolts, but not tight up against the underbody), would that deliver a rattling noise that starts at 2100 revs but disappears at 2400rpm?

Jamb something between the shield and floor then check if the rattle stops.

If the flexible joint in the exhaust just below the turbo is a bellows type then the bellows eventually stretches leaving the lower end to rattle on the internal limit stop.

Originally Posted by Graeme

Jamb something between the shield and floor then check if the rattle stops.

If the flexible joint in the exhaust just below the turbo is a bellows type then the bellows eventually stretches leaving the lower end to rattle on the internal limit stop.

I do have the flexible bellows, noise does appear to come from that direction.
The front pipe is only about 40k old as did away with front muffler when re-mapped and fitted new pipe.
Maybe a bunky bellows.
Will look.

Originally Posted by vbrab

For months I have had a noise that sounds like something touching as engine /fan rotates.
Starts at about 2000 rpm and ceases at 2400, and I cannot hear it when in top (auto).
Sounds more like a "clattering" that more happen if say a blade was touching something as it rotated.
Have checked all over nothing loose, nothing touching, no loose heat shields.
From drivers seat sound appears to be coming from left of centre nearer the firewall rather than up near engine front

If I place my hand on the high/low range selector I can sort of feel a vibration that matches the noise am hearing.
Vibration through H/L selector stops when noise stops.
Cannot see anything loose on H/L linkages ect (but bit hard to get close up to). I do have a scope if there is some place I should be looking.

I was thinking something to do with torque convertor/drive plate (from the sound of it), but it has gone on so long I doubt it is in that department.
Has near new engine mounts, but original gear box mount. Do gear box mounts perhaps add noises /vibrations?

Just an annoying noise, but I'd like it gone if anybody can suggest what to look at.

I have what sounds to be the same as yours. Mine is coming from the hand brake. I can remove the noise by gently pulling on the hand brake during that rev range the rattle disappears.

Originally Posted by trout1105

I had a simmilar sound coming from under my D2a just before the output bearing in the transfer case carked it.
Have a look at that before you celebrate

I am optimistic that hopefully not transfer case bearing as transfer case fully rebuilt by very reliable trans guys less than 25k ago.....but stuff does happen.
I ONLY get the noise (which sounds like resonance linked to revs rather than rumble or anything actually hitting) between 200-2400 rpm, and once it in top, sweet as.
As noise appears to emanate from passenger side near front exhaust pipe i am inclined to think (hope) that is as others mention, possibly loose flexible lining in flexible area on front pipe.
I recently gave away a new front pipe, damn!!

On my 99 TD5 D2, I had a very pronounced rattle when accelerating from stopped. If I pulled the handbrake on slightly then it would stop. I had new handbrake shoes inside the drum fitted and everything was fine after that as far as rattles go.

on my 2000 V8 D2, there was a type or flange behind the harmonic balancer which was rattling. I cut it out and that stopped. Good luck

1999 td5 Oxford blue 365k 6 seat rear aircon

TJM bar, rear bar, ECB rack, Hdi lights, Aldi 9” LED Spots, vhf 4.5db, EGR blank, ACE disabled, rear bags removed, reverse camera, in line thermostat, engine watchdog, brass diff plugs, Tfr case done, auto done, amigos away making trouble elsewhere, (HSE interior and CDL next)