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Rattle From Engine Bay Under Acceleration

Old Jun 3, 2026 | 05:32 PM
  #11  
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Originally Posted by JP Defender
NorCal Defender - Did you ever figure out what was causing your noise?
Sadly no, the noise is worse than ever. Sounds like a bunch of marbles on lite acceleration under load (worse going up hill) only happens when engine is warmed up, never when cold and no abnormal noise on cold start either, just on acceleration in lower rpms 1600-2100 in almost all gears. Lr replaced 2 electric superchargers, spark plugs, cam actuators, pcv valve, and something else I cant recall. I plan to get some better video and audio and open another case with LR. Sounds like a POS driving down the road, can be heard with Windows up or down inside and outside of vehicle.
 
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Old Jun 3, 2026 | 06:03 PM
  #12  
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Having the exact same issue! 1500-2000 rpm under load and seems to be getting worse
 
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Old Jun 3, 2026 | 06:14 PM
  #13  
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Originally Posted by JP Defender
Having the exact same issue! 1500-2000 rpm under load and seems to be getting worse
Tech assist was leaning in the direction of timing and pinging, that's what it sounds like. But engine is smooth and doesn't stumble, no check engine light. Tried running 93 and no change, I'm in Ca so I always run hightest octane 91 from shell or 76. I'm wondering if it could be related to the broken manifold bolts or if there's some heat shield causing it. Everything is so tucked and hidden in this motor it's so hard to say. To me the noise is maybe more driver side firewall area of engine. Timing chain is on the back of this engine too, nothing seems easy going working on this vehicle. Hope you can get it sorted, are you in Ca? Have you had dealer diag yet, what year and miles?
 
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Old Jun 3, 2026 | 06:24 PM
  #14  
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I'm in PA. 2024 with ~34k. I had it at the dealer and they said the could not replicate the noise. Service mgr took it home for the night and nothing. I feel it's getting worse and to the point my 15yr old asked what was the noise! I need to schedule another appointment and ask that a tech rides along to hear the noise. Very frustrating
 
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Old Jun 3, 2026 | 07:05 PM
  #15  
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Originally Posted by JP Defender
I'm in PA. 2024 with ~34k. I had it at the dealer and they said the could not replicate the noise. Service mgr took it home for the night and nothing. I feel it's getting worse and to the point my 15yr old asked what was the noise! I need to schedule another appointment and ask that a tech rides along to hear the noise. Very frustrating
Yes, definitely rd test with ship Foreman or master tech for sure, and if you have video or audio supply that too. If suggest opening a case with LR ahead of time and schedule the drop off, that way it's a priority and will get more attention. Keep me posted, reach out and dm anytime if you need more info. Mine was down for over 3 weeks within 3 visits for this with an open case so far, noise still present. Noise should be very easy to duplicate, sure hope you can get to the bottom of this. It's been a while since I posted about it, maybe throw up another new post here and FB, maybe someone has some new info to report or LR tech may chime in.
 
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Old Jun 3, 2026 | 08:09 PM
  #16  
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Could this literally be as simple as the broken exhaust manifold bolt head being caught in a spot and rattling?
 
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Old Yesterday | 08:37 AM
  #17  
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Could be I guess however it only happens between 1500 - 2000 rpm and under load. Nothing at startup or any other time.
 
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Old Yesterday | 12:07 PM
  #18  
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Originally Posted by JP Defender
Could be I guess however it only happens between 1500 - 2000 rpm and under load. Nothing at startup or any other time.
Maybe one of the bolts sheared or loosened and now the exhaust manifold is leaking, and is only making the noise under certain load conditions.
 
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Old Yesterday | 09:49 PM
  #19  
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Hi all, new here but have been lurking a while. I have experienced the same rattle in my 2025.5 P400 on occasion, under the conditions described. I am convinced that it is spark knock from poor quality fuel combined with higher engine/air temperatures. Seems to improve with 93 or 91 from stations that are selling lots of premium and turning their inventory. My guess is that I got “winter” blend fuel in warm weather when it had the issue. 20k on my Defender and 75% of miles is towing an enclosed trailer and getting 10 mpg, so I am working it. I am in the upper Midwest and the fuel formulations change with the season.

Also…although not a true authority on the subject…I am a mechanical engineer and did research on the drivers of knock in forced induction engines for a former employer that is an engine manufacturer. Knock is all about charge (air plus fuel) temperature. Warm charge air, low fuel flow at these rpm’s, low humidity, and low octane = knock.

Will report back if my assessment of improvement with 93 changes or remains consistent.
 

Last edited by Blade004; Yesterday at 10:07 PM.
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Old Yesterday | 10:39 PM
  #20  
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Originally Posted by Blade004
Hi all, new here but have been lurking a while. I have experienced the same rattle in my 2025.5 P400 on occasion, under the conditions described. I am convinced that it is spark knock from poor quality fuel combined with higher engine/air temperatures. Seems to improve with 93 or 91 from stations that are selling lots of premium and turning their inventory. My guess is that I got “winter” blend fuel in warm weather when it had the issue. 20k on my Defender and 75% of miles is towing an enclosed trailer and getting 10 mpg, so I am working it. I am in the upper Midwest and the fuel formulations change with the season.

Also…although not a true authority on the subject…I am a mechanical engineer and did research on the drivers of knock in forced induction engines for a former employer that is an engine manufacturer. Knock is all about charge (air plus fuel) temperature. Warm charge air, low fuel flow at these rpm’s, low humidity, and low octane = knock.

Will report back if my assessment of improvement with 93 changes or remains consistent.
You're right it sounds just like engine pinging, tech assist had my dealer bump up octane levels above 91 (highest we can get in ca is 91) and all I use. The dealer checked at 93 and I even consistently add octane boost during my fill ups to be 93 octane and it's still a constant rattle and no codes stored.
 
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