As usual Im trying to trace down some noise or leak, this time Im getting a rattle/click type noise at idle. It only does this when hot and when you rev it up it goes away by 1250 rpm. At cold Idle it is quiet and reved up it sounds nice and smooth. So far I have tried 5w40, 15w40 and what I have currently 10w40 no change in noise. I ran the oil pressure readings and they where all good. 14psi at hot idle. A couple weeks ago I had to replace the driverside cat because it was making a horrific clatter when deaccelerating, Im wondering if this noise Im trying to find now is the other cat, just wasnt sure because the driverside cat only made noise on deaccelaration. This noise it makes kind of sounds like a diesel motor, where the noise is not completely consistent with rpm. I have cralwed around underneath with a dowel rod trying to pinpoint the noise but, nothing conclusive. Im running by the exhaust shop tomorrow to see if they can tell if it is coming from the cat while up on a lift. Any one have any ideas what could be making the noise? Its definetly coming from down underneath, really cant hear it under the hood. Any ideas?

 

Bang the cat with your fist and see if it rattles. If your engine only rattles when hot then I don't think it's the cat though.

 

Cant get the cat to rattle by banging, but I also couldnt get the other cat that made horrific rattles to make noise when banged. It also only made noises when hot, but it only made its noise on deaccelerating not at idle.

 

Welcome to the club. Unfortunately, you a now part of an elite LR club. Highly doubt ts your cat that's making the racket. In your description you liken the "rattle" to a diesel engine. Sounds like valve-train/ cam-lifter noise. You are not alone my friend.

I have/ had the same noise (it comes and goes) for months. If you nor your exhaust shop can trace the sound to the other cat, then try an engine flush with some ATF to help clear the oil passages. Drain your engine oil and replace it with six quarts of ATF. Run the engine at nothing higher than idle speed for 30-35 minutes. Monitor the temp at all times. Then, drain ATF and remove the oil filter and replace with fresh engine oil and new filter (Mobil 1-301)

How many miles are you showing?

 

thanks. Its at around 102k miles. The sound is definetly coming from the bottom, you really cant hear it at the top with the hood up, but you hear it with windows down and your next to another car or building or if your underneath.

 

Had the exhaust shop put it on the lift and check out the other cat and it is fine. The exhaust guy said the engine is knocking, I also stood underneath and it really sounds like its coming from the bottom of the engine. The noise is gradually getting louder, I have only driven this thing around a thousand miles since I bought it, am I already looking at a mjor engine repair? Any thoughts on what could be causing the noise? Its very much a tapping/rapping type noise that is the loudest when listening at wheel wells and underneath, not very loud under the hood. What could it be?

 

So was it doing that when you bought the vehicle?
The source of noise can be misleading since they echo and reverb throughout the engine. With that said, a rod knock is a deep thud in the lower part of the engine, this is serious and indicates a big problem. A metallic click or tick is something else in the valve train and many 2003/2004 discos do that, some have been running like that for 45k miles.

 

Here is the audio/video of the sound. it is the rapping/tapping sound. What do you all think?

 

That describes exactly what mines does and about a dozen others. I have replaced just about every moving part in the engine, the only original parts are the pistons, crank, valves and valve springs and it still does it. I have tried different weight oils and it makes no difference.

 

Its not a deep thud its more of a tap or clacking, but I dont think its coming from the valve train, maybe midway up the motor. It was not doing this when I bought it, it really started a couple weeks ago after I switched to 5w40 synthetic oil from the unknown oil that came in it. I have since switched back to 10w40 mobil 1 dino oil.