metallic rattle on acceleration

OK so maybe this comes down to cr*p driving skills, who knows ...


When gently accelerating at SLOW speed (under 20mph), in say 3rd gear, I get a metallic rattling noise for a few seconds (front below). If I repeat the maneuver in 2nd gear, no noise. So the obvious solution is to drive in the "correct" gear?? :clap2: The problem is that (in this example) 2nd gear feels wrong - feels too strong. So I often find myself in the annoying situation of driving at too low a gear just to avoid getting the metallic rattling noise.


I've driven many other cars which will give a slight rattle or vibration if you accelerate at low speed in too high / "wrong" gear. Obviously that's not correct driving behaviour. My concern is that my TD4 (2005 model) has a particularly loud rattle, and at a gear ratio which "feels" correct.

I'm wondering if this is a sign of problems with VCU bearings, diff bushes, IRD (eek), or something else.

NOTE: All of this happens only at very slow speed driving, no other apparent problems, no rattling in neutral or idle or freeway driving. Sounds like its coming from under the front.

Is this normal for a Freelander?

could there be a loose part on your exhaust as far as I know you do not get a metalic rattle on VCU or diff bushes

your not talking about the diesel 'pinking' noise that can occur on acceleration from low rpm ???
i.e. mentioning it as it sounds sort-of-metallic .. and might be more pronounced in a higher gear ..
usually at rpm before the turbo kicks in ..
( if so .. it's normal .. and fuel / injection related ..
( i've noticed 'bp ultimate' fuel more or less negates that noise

I'd be suspecting a loose baffle in one of the exhaust boxes.

Singvogel.

I had a rattle, It sounded like a wire flapping about. Someone suggested diesel pinking, turned out to be a faulty HP sensor at the end of fuel rail.

I've got something that sounds like this and I have put it down to a loose heat shield on the front downpipe.

thanks guys - much appreciated. will investigate your suggestions and post solution if/when i find it ...

after just been out for 30 miles .. reckon i'll rethink 'pinking' as a 'metallic rattle'
( put it down to over active imagination )

anyhowz .. about a mile 'n half out .. in town .. 30 mph 'n a tad .. in 4th gr. ..
'L' driver in front drops speed goin' over a very small hill ..
found myself at about 25 mph .. or less .. in 4th just before peak of said v.s. hill ..
very gentle on the pedal ( nudging it over as 'L' had decided to up speed .. 40 limit in view ) .. noticed peak in engine vibe
as it went thru the 1200 rpm mark .. .. if anything were to be loose ..
it would certainly rattle .. engine were cold-ish as well ..

thanks hd3. i researched "pinking" after you mentioned it - had never heard of it before, and now understand what that "tinkling" sound is which I've often heard in cars before. always wondered what it was. pinking almost sounds like lots of little sparks! the noise i'm getting is a bit louder and rougher.

feel a bit dumb trying to "explain" a sound in a forum. surprised sir ming space twot hasn't ripped me off yet!!

thanks for teaching me something new!

as long as you have found it all ok but please do not keep doing it or it will not be just the tinkling of the tappets you will be hearing banging from the big ends

I had a rattle that was driving me mad. Turned out to be one of the Allen bolts in the air filter box (at the back) wasn't in properly and was rattling on the captive nut!

It's probably diesel clatter, not really pinking. Same idea tho! Bad diesel clatter sounds like your big ends have gone, otherwise it's a rattle more often at low revs, can be caused by dirty injectors among other things, making the engine labour at low revs is when you usually get it! The revs you refer to driving with are really too low for the engine to be happy hence labouring!


DD

hd3 said:

your not talking about the diesel 'pinking' noise that can occur on acceleration from low rpm ???
i.e. mentioning it as it sounds sort-of-metallic .. and might be more pronounced in a higher gear ..
usually at rpm before the turbo kicks in ..
( if so .. it's normal .. and fuel / injection related ..
( i've noticed 'bp ultimate' fuel more or less negates that noise

Click to expand...

Not 100% certain, but following hd3's advice and using BP Ultimate (and a diesel conditioner additive), much of the clatter seems to have disappeared. Must have something to do with a British car liking British fuel

I always thought pinking was for petrols caused by weak mixture and compleatly different to diesel rattle which is more mechanical ie worn piston rings?

I got a metalic rattle when i am labouring abit, comes from the subframe. Probably not the same as yours though

seraphin said:

Not 100% certain, but following hd3's advice and using BP Ultimate (and a diesel conditioner additive), much of the clatter seems to have disappeared. Must have something to do with a British car liking British fuel

Click to expand...

Ho Ho - I'm using Shell V-Power with added cheapo 2-Stroke.

A case of my Austrian-built engine liking Dutch fuel, perhaps.

I do have a metallic rattle - loose baffle in the cat. (dpf)

I always thought pinking was for petrols caused by weak mixture and compleatly different to diesel rattle which is more mechanical ie worn piston rings?

Click to expand...

pinking in petrols be pre-ignition .. fuel ignites too soon / too fast ..
the engine .. in a way .. tries to run against itself ..
weak mix .. too low octane rating .. over advanced ignition timing .. hot spots on piston crowns

diesel rattle / clatter / knock is due to the way the injected fuel expands once ignited ..
the td4 ( m47r) and no doubt many other similar engines .. employ two injections of fuel
per piston-rod power stroke .. there's a pre-injection and main-injection .. no doubt that
will effect the 'sound' of said diesel knock .. .. (to me it sounds more like petrol 'pinking') ..

there be other differences as well compared to older variations of diesel engines
combustion chamber shape .. injection / timing controlled by a microprocessor ..
common rail fuel delivery .. electro operated injectors ( as opposed to totaly mechanical )

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text from : ' The quiet diesel evolution '
The quiet diesel evolution

" .. injection is not instantaneous; “injection lag”—the time required to build injection pressure and get it to the nozzle and “pop” it open—delays things. Once fuel is injected, “ignition lag” also occurs.
.. Injector design and spray pattern, compression temperature, fuel cetane rating, and more influence ignition lag.
.. The “lag” during the compression stroke tends to cause diesel fuel to ignite spontaneously, thus creating the familiar diesel knock or “clatter” sound; upon ignition, cylinder pressure suddenly rises and “rings” the cylinder. "

~~~

compression and combustion pressures in diesels prior to microprocessors ( pic ) :

( if pic don't display .. it's in the above article link )

~~~

I got a metalic rattle when i am labouring abit, comes from the subframe.

Click to expand...

if i sit in neutral .. and slowly run the rpm from idle to 2k ..
there's a spot right at 1200 which produces the strongest resonance ..
used to make the door pockets rattle .. 'till i snugged up the torx screws ..
now it makes the dashboard area vibrate with a buzzing sound ..