Got an L200 that sounds like the engine is trying to escape through the bonnet. It’s the newer shape 2006-onwards model.
2.5 diesel, auto gearbox.

Had a problem where it wouldn’t start at all so has been in the local garage for about 3 months. Turned out to be some kind of pressure hose/switch thing but it took a lot of trial and error.

Apart from the noise it now runs the best it ever has. Fuel economy up, more “poke”, it just sounds awful. Really rattly, seemingly coming from rear of engine, I’d probably say top end rather than bottom but it really is too loud to pinpoint. The noise disappears completely from around 2000rpm if you rev it in neutral. If the engine’s under load (i.e. when driving) the noise remains, although it does get better the higher the rpm. If you’re driving along maintaining speed and find the sweet spot where there’s very little load on the engine the noise disappears, but comes back if you either press the accelerator or take your foot off and start coasting. The local garage is flummoxed, because apart from the noise it’s great.

Can STW’s resident experts think what might possibly be the cause?

Loose heat shields, something else loose, air inlet rattling where pipes join, loose baffles in exhaust.

Pop the bonnet and with an assistant on the throttle, get looking and listening.

Flux capacitor has come out of alignment failing that it’s definitely the nuclear reactor that needs a clean with some white spirits.
Failing all that some sort of heat plate or whatever is on top not quite tight enough?

I’ve had BIL round with screwdriver/ear defenders and it seems to definitely be engine rather than something outwith being loose.

Hang on, I’ll do a YouTube video

Water pump on way out ?

Timing belt and water pump were changed last year and timing was re-checked as part of the trial and error in the garage recently.

Rad fan ???

As a purely speculative crystal ball guess That sounds very similar to when an injector clamp is loose.

Sounds like your thrunge impeller gasket is going widdershins.

The ivy is ruining the pointing on your wall

Sounds like “injection” or “firing” noise to me, but check the engine and gearbox mounts, as sometimes at low rpm the engine oscillation and movement can be large enough on worn mounts to cause it to touch the chassis and resonate horribly!

Does the noise sound different then the engine is cold? Modern diesel engines sound very different when running in “multi-injection” mode as to when they run in “single-injection” mode, and sometimes this sounds like an issue when it isn’t and the modes they run in are speed and load dependent. For example, start the engine from cold, leave it idling, and you can spot when it gets warm enough to swap into multi mode just from the noise change. Certainly check the security of the injector fuel feed pipe work and the injectors themselves, as pressure pulses at low speed can cause these to resonant.

Injection too advanced?
I don’t know these engines but an increase in economy/performance BUT with an increase of ‘diesel clatter’ is an indication of injection that’s very slightly too far advanced.
Especially if the fuel pump had been removed.

That sounds just like my 2009 2.4l Transit, I drive it for months like that and I’m pretty sure it was the dual mass flywheel falling apart. The in-house garage refused to look at it but the next driver/keeper of the van said it went in for a new flywheel and clutch later that year.

It was a clattery noise that increases with revs, after a while it started to quieten down, I imagine it had blended most pieces of the flywheel up 🙂 Occasional the clutch would fail to return fully.

Just remembered I also took a ‘video’ when it was particularly bad, to try and convince the mechanics to sort it.

I’ve been thinking it’s something to do with fuelling, will have a look at injectors. Timing was checked when it was in the garage so it’s not that.

It’s an auto so don’t think there’s a DMF involved, but I guess it’s worth checking the transmission anyway.

Cheers for the ideas so far.

Loose engine mount?

An update if anyone’s interested. The torque convertor wasn’t correctly bolted onto the engine. The noise was a loose bolt rattling around inside the case. Not quite enough to write it off but still about £1000 to fix, something to do with a flex plate taking the brunt of the damage.

Now I just need to get the bill from the first garage to see what they did when sorting the engine problem out. Can’t imagine they undid anything transmission related, but you never know.

still about £1000 to fix

Ouch! ☹️