I have a high mileage (165,000) 4.2SC that has an odd reverberating noise around 1900-2200rpm. It does it in every gear regardless of speed so I've partially ruled out drivetrain.

I wondered if at 165K it's feasible for the CATs to be breaking down or be partially blocked giving me this reverberating/humming noise. It's very loud, louder than the engine, but almost seems louder inside the car than out. The noise goes away if I put my foot down or back off, typically the throttle load I guess is about 25%

I've tried recording it, but my phone doesn't pick it up at all so I know this isn't going to be an easy one to diagnose - just wondered if anyone else had experienced similar?

Dan

 

Does it do it if you sit still and rev it to those revs, and does going up or down a hill make any difference?? 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-

Process of elimination............., engine / transmission mount?

does the vibration occur stationary during torque stall ? don't over heat the trans! might eliminate transmission Regards
Royston

2008 4.2 Supercharged Autobiography
1994 Classic Vogue SE
1999 Rover BRM
1987 Rover Vitesse Twin Plenum

Loose heat shield somewhere? As said above, can you replicate it stationary?

Get underneath with a rubber hammer and bang at stuff to see if there is anything loose. There is nothing that can't be fixed with a hammer😜😜
FFRR 4.4 SDV8 Autobiography Santorini Black.
KIA E-Niro 4+
2010 LR D4 Commercial 2.7 TDV6

Thanks for the replies:

It only does it whilst driving and under load, worse when light throttle is causing the engine to labour slightly.

The noise is so deep and boomy I don't think it could be an exhaust shield as these tend to be a tinny rattle. but I will add them to the things to check.

I hadn't considered engine/gearbox mount, thanks. 

Well I found a second hand exhaust, cats back so we'll see if this resolves the issue, worth a punt for £100 I thought.