On hard acceleration I get what sounds like engine knocking between 1900-2500 rpm. Mostly noticeable uphill but also while accelerating to overtake on a level road. Some days it's there (can pick up with a keen ear) even from lowish rpm with little load while some other (few) days it's totally absent, no matter how hard I am on the throttle.

Ambient temperature doesn't seem to be a factor. Engine temperature isn't a factor either, as it does this even if not up to temp. The knock / rattle dissipates beyond the 2500 rpm mark and reappears around 4000 if pushed hard. Which I've only done a handful of times ever. It also goes away if I lift my foot off the pedal.

I've been using 95 RON unleaded as well as 100 RON with no difference. In the video, it's 50/50 mix with würth octane booster just for the experiment.

Most noticeable in the beginning and in the end of the video. It's faintly heard in the background

https://vimeo.com/804604242

And it's beginning to drive me nuts as it ruins an otherwise perfect car

Any ideas appreciated

Last edited by vs322 on 12th Mar 2023 7:34pm. Edited 3 times in total

Vanos?

I doubt it. They had no issues when I did the chains and hg last year. Also no timing error codes thrown. In fact I get no error codes on my car other than trivial stuff.

I have the GAP IID BT. Is there a way to determine whether or not my engine is actually knocking by using the diagnostic?

On a separate note, I've looked extensively underneath and found the right side heat shield just above the cat, to be somewhat loose. Bent it slightly to increase the distance from the chassis and this seems to have helped although not for long. So it could well be a coincidence or the placebo effect. But I definitely don't get any improvement with higher octane fuel (have tried a full tank in the past) or the octane booster, that's for sure.

I've just cleared the engine adaptation values and will take her for a spin later on today, see if that helps although I'm not holding my breath...

Another point worth mentioning, I had a similar issue right after last year's engine repair which turned out to be an exhaust leak, result of a loose bolt. This one sounds a bit different though and one might miss it if not listening out for it.

Need an account to watch the video...!! Pete

__________________________________________________
2014 L405 Autobiography SDV8 4.4 Loire Blue Ebony interior
2011 L322 Vogue SE 4.4 TDV8 Baltic Blue. Parchment over Navy Interior. Sold
2012 L322 Autobiography 5.0 Supercharged Ipanema Sand, Jet Interior. Sold
2002 L322 Vogue 4.4 V8 Epson Green, Ivory over Aspen Interior (Fatty Offroader) Sold
-Click for Project Fatty off roader-

Sorry, Pete. My bad.

Should be working now First instance around the 4"mark. Again, need to focus on the background to pick it up. Earphones would help.

By the way, I had to run some errands downtown and on my way back took a shortcut through the...red light district. Thanks, Google... Guy behind me, probably having some...urges I guess, kept honking for me to go faster, to the point of eventuallt getting on my nerves. So I floored it. Once past 2,5K rpm there was no more discernible knocking, just the mean growl of the V8 resonating through the alley. I'm sure I must have scared some ladies out of their beds

I've probably ruled out any engine pinging / knocking etc. In a careful observation, the noise seems to occur between the 1900 and 2500 rpm range (most noticeable at 2300-2500). But it is not just while the rpm increase but also on their way down during an upshift (as the rpm needle drops back through said range). It has to be something loose that resonates at the particular frequency. Can't find it though ...

The front driveshaft had problems on early cars, could be a UJ moving.

It has had the recall done...

I'm at my wits' end with this noise...Have inspected everything under the bonnet.
For a moment I thought I'd found it as the power steering cooler was loose. They had forgotten to snap its pipes back, into the fan shroud clips. Turns out this wasn't the culprit.
Fitted a rubber grommet around the thin A/C pipe on the rh side. Nope.
I revved the engine gradually until 6-7 k rpm in N. Nothing.
With the foot on the brake, revved in D through the 2-2.5K rpm range briefly. Nothing.
Seems I am only able to reproduce the noise with the car moving.

Gearbox oil is fresh, transfer case and diff oils are 16 months old... No issues whatsoever with the drivetrain.

I've checked the brakes' dust shields, too.

The noise can only be heard inside the cabin. If a window is open, the road noise covers it. It cannot be heard while driving in tunnels, beside walls etc...

Had spoken earlier with a former LR dealership, now authorized garage about the issue and today dropped by to pick up their master mechanic, take the car for a spin and get his opinion.
He suggested that the engine mounts could be on the way out and since the HG and timing chain repairs last year, the engine's frequencies may have changed as well, resulting in different parts resonance etc. He also commented that the noise is so minor that he would probably send any car with similar issue on its way without any second thoughts. Maybe it's just me, being pedantic... But this noise sure wasn't there before.
I'll let it be for now and have the engine mounts replaced at next oil change.

Check driveshaft support bearing on my TD6 was failing and did knocking noise under heavy acceleration

Grazie! Will do

Wrapping this up once and for all:


Today I had the rear subframe bushes replaced. Garage felt like dropping the frame a bit more to create some space (following Rave for rhe most part) to work. In order to avoid flexing the exhaust and stressing the manifolds, they opted to remove it altogether and guess what? Right hand side neck bolts were loose. The mechanic asked me if I was experiencing any odd noises. I said yes, for more than 2 years already. Well, he said, it's gonna be quiet from now on...
I had taken up the matter with the garage that did the HG and timing chains; said it was all okay. Then another garage.
I'm picking up the car tomorrow. If this is indeed sorted, I'm buying these people a cake 🎂.

Glad that's finally sorted....  Pete

__________________________________________________
2014 L405 Autobiography SDV8 4.4 Loire Blue Ebony interior
2011 L322 Vogue SE 4.4 TDV8 Baltic Blue. Parchment over Navy Interior. Sold
2012 L322 Autobiography 5.0 Supercharged Ipanema Sand, Jet Interior. Sold
2002 L322 Vogue 4.4 V8 Epson Green, Ivory over Aspen Interior (Fatty Offroader) Sold
-Click for Project Fatty off roader-

Hey Pete,

Really, I couldn't be happier. While I had come to realize it had to be something insignificant, the fact that no one seemed to be able to identify it speaks volumes about garages here.
Not only had I complained about it, I had offered an opinion on the possible culprit and was assured it was okay not by 1 garage but two. I had even been charged for the troubleshooting and it is not the only thing I have been unduly charged for
A year and a half ago, I had a slight leak from the radiators top hose and couldn't find the genuine item so I resorted to an aftermarket one. Which leaked as well. So I asked the same garage that had signed off the exhaust as being okay if they had a genuine replacement. I ended up waiting 1 week and agreeing on a brake job that wasn't exactly due. When I popped the bonnet I found the SAME aftermarket hose that was leaking feom the same coupling!!!! Ended up importing and installing the hose myself.


Edit: Now all sorted; two birds with one stone

Click image to enlarge

Click image to enlarge