Disco gods are after me My Disco had a random thud, it did not change appreciably with RPM and vanished at higher rpm,maybe 1200-1500. I was checking the alternator under load and cold oil pressure it is good 48 at start 30-25 as she warmed up (my monitoring cell was charging) so no solid on the temp.

It sounded like a loose exhaust pipe hitting the body, but it is not that,I checked. It was pretty global so not isolated to any single location.

I shut down and have restarted 3 times since no noise - any ideas.

I do need to take the Disco for a run to get her well warmed up but this was very odd.

No codes, no over pressure, temps are good 183-194 running

 

does it only thud under load while driving or also while revving in park? I'd check all engine and transmission mounts. exhaust would rattle more than thud, from my experience.

 

@tnrangerover It was in park at idle,it was a really weird sound. I know rocker ticks, liners increase with rev's and are "more metallic".

• You could not hear it from the cab with hood up, I was turning things on 1 thing a time to check alternator voltage draw.
• I noticed it after one trip in and out, tried to isolate it no luck
• Rev'd the engine at the throttle body to see if increased, no real change
• Got in the cab I could not hear it
• It will drive me nuts - could just be one of those things

 

my old 92 Range Rover made a pop sound at about 45 mph. no vibrants or anything weird that I could find. It didn't always do it, and it only happened at one road speed, but never while parked or in neutral. it was so odd, but I just learned to live with it. in the meantime, if you've got a spreadsheet going, then just mark your mileage and the date of the sound and keep a record of it every time you hear it.

 

Did the exact same test today nothing other than a bit of lifter tick, crazy stuff.

 

Got a suggestion from my club forum fuel detention in the exhaust or cat. Did some research it is right sound, I am doing exhaust work tomorrow and I can also whack the cats and is if stuff is rattling.
Hit all the bolts with a whack of wd40 so I may have introduced enough fumes in the exhaust as it burned off to create the problem, had kind of forgotten about the WD40 and possible fuel issue

 

Richard, did you check motor mounts, as suggested by tnranerover?

Also, just for clarification...is it a thud (like somthing dull hitting something dull) or Numm, numm, numm (rotational noise, like main bearing)?


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@The Deputy thud almost like an axe hitting wet wood or thick oil coming out of a plastic bottle. Not rotational at all almost no change with rpm increase. As it happened when the Disco was stationary I only did a visual of the motor mounts, they look ok.

I checked the cats cold by hitting them with a rubber hammer no noise
I did notice the front driver side o2 has carbon around the base, like an exhaust leak.
And I do have a couple of exhaust leaks
No codes or pending codes
I did find a video of a similar noise from unspent fuel detonating in the exhaust very similar sound.
Has not occurred - did the same alternator test today, the Disco has not moved. 3rd start to full temp without a reoccurrence

 

So I undid and re torqued the right side y pipe connection, the driver's side need more penetrating oil they are locked up solid.

Checked everything and fired her up the

Videos below is what she sounds like, there is a concrete 1/2 wall to the left so a bit of sound reflection, also there was a almost rattle sound for about 4 minutes until she completed heated up - I have not tightened the intake or exhaust manifolds yet :

Cold start


Up to 150-160 deg just before heading out


After the drive 188 - 186


As far as I can tell other than a bit of tick at idle she is running fine

 

Well still have a tick until warm maybe 5 minutes then nothing, time for an oil change. Tried to get the sound on the phone no joy, basic engine noise is louder when driving

Need to check for intake or exhaust leaks, could still be a sticky lifter or bad rocker - but I have spares

Power is good o2's are reporting better which is priceless