Engine rattle at low revs/light load but only in 5th/6th gear

[Daza101]

Hi,
I was hoping someone might have an idea as to what my issue could be please.

I've got a 2013 Galaxy Titanium X 2.0 Diesel with Powershift Gearbox. It's covered just under 100k miles, 80k miles of which I have driven since buying it around 8 years ago. It has a full main dealer service history including all Powershift gearbox services and the cambelt and water pump were done within the last year.

Around 9 months/6k miles ago I started getting what sounds like an engine rattle which only occurs at low engine revs (1500-1800 rpm) and only in 5th and 6th gear when trying to maintain a constant speed or on very gentle acceleration. It doesn't occur in gears 1,2,3 or 4.
It occurs whether the engine or outside temperature is hot or cold and doesn't mater if driving with the gearbox is in automatic or sport/manual mode.
There are no error lights or fault codes when read with OBD reader and no odd noises or rattles if the engine idles or is reved while stationary.

The car has been to the main dealer 3 times for this issue. Twice I was told it sounded completely normal but on a test drive with a senior technician he suggested the noise/rattle was injector related. Leak off tests were performed and all injectors were replaced under warranty as they weren't with expected tolerances.
The new injectors have made no difference to the rattle and I've been told to just live with it!

Despite the noise only occurring in 5th & 6th gear, while under light load, I believe it is coming from the engine and not the gearbox.

The only other time I hear anything similar is when a DPF regen is happening and the engine seems to get rattlier/noiser for a few minutes. This has always been the case whereas the issue I have here is fairly recent (9 months max).

Is it normal for Diesel engines to just start getting noisy when they approach 100k miles despite being well maintained?
Is there anything specific that should/shouldn't happen only at low revs/light load in 5th & 6th gear?

Any suggestions would be much appreciated.

[Mirez]

Diagnosing noises over the internet is notoriously difficult unfortunately but to answer your question, no. Unlike a petrol engine, a diesel is only about a third of the way through its life at 100K and shouldn't be noticeably louder then it was on day 1.

There are however a lot of accessories on modern diesels, most of which aren't quite so robust. One of them is the EGR and the other is the DPF, so it's interesting you mention that although it's normal for the DPF to make an engine chug a little whilst its doing a regen. The EGR is likely to be fully open at the time you describe and at 100K it's also likely to be very silted up so I'd look here as a possible cause.

[Daza101]

Diagnosing noises over the internet is notoriously difficult unfortunately but to answer your question, no. Unlike a petrol engine, a diesel is only about a third of the way through its life at 100K and shouldn't be noticeably louder then it was on day 1.

There are however a lot of accessories on modern diesels, most of which aren't quite so robust. One of them is the EGR and the other is the DPF, so it's interesting you mention that although it's normal for the DPF to make an engine chug a little whilst its doing a regen. The EGR is likely to be fully open at the time you describe and at 100K it's also likely to be very silted up so I'd look here as a possible cause.

Thank you very much for your suggestions.
I'll try to take a look at the EGR.
The car's due an MOT in around a month so I'm guessing if there's an issue with either the EGR or DPF then the emissions are also likely to be bad as well.

[Mirez]

Sometimes but not always, a heavily restricted EGR for example will still open but the flow is unlikely to be monitored.

[Solentview]

I am probably way off course here, so ignore this if it sounds stupid, but our Alhambra developed a vibration at steady 50mph/1500rpm-ish, and only showed itself in high gears at a steady speed/light throttle with wheels dead ahead on the motorway. That turned out to be the tripod bearing inside the inboard joint of the nearside driveshaft. I am not familiar with Ford driveshafts and ours was vibration rather than noise, but it might be worth checking the driveshaft joints if only to eliminate a possibility.
When I went underneath and grabbed the shafts, the offside was rock-solid at both ends, but the nearside rattled nicely inboard. And a professional technician failed to diagnose that one, as well.

[Daza101]

I am probably way off course here, so ignore this if it sounds stupid, but our Alhambra developed a vibration at steady 50mph/1500rpm-ish, and only showed itself in high gears at a steady speed/light throttle with wheels dead ahead on the motorway. That turned out to be the tripod bearing inside the inboard joint of the nearside driveshaft. I am not familiar with Ford driveshafts and ours was vibration rather than noise, but it might be worth checking the driveshaft joints if only to eliminate a possibility.
When I went underneath and grabbed the shafts, the offside was rock-solid at both ends, but the nearside rattled nicely inboard. And a professional technician failed to diagnose that one, as well.

Hi,
Thanks for your suggestion.
The noise is a kind of mechanical rattle which I'm positive is coming from the engine.
I have checked the drive shafts from underneath but don't seem to have much play or rattle.

As per the previous suggestion, I'm leaning towards thinking the EGR could be clogged up especially given the mileage.
I've watched a couple of Youtube videos showing how to remove/clean/replace it but to be honest it's a little beyond me.
The cars due an MOT soon so I'm thinking if the EGR is the issue then the emissions are likely to be bad during the MOT so I'll ask the garage to take a look then.

[Solentview]

A mystery! Our Alhambra (BRT engine) has a WAHLER EGR valve and suffers from what VW Customer Services refer to as 'EGR bounce', insisting that it is a perfectly normal part of BRT operation. This shows itself as a momentary misfire usually when accelerating at about 2000rpm, but it does not generate any untoward noise. The valve was changed under the original VW warranty and then again about 6 years ago, but even a brand new valve does not entirely banish the issue, which very slowly gets worse as the valve (presumably) cokes up.