I have a 2000 Disco II with about 143,000 miles on it.

Recently, I started hearing a clattering under acceleration. The noise is not present at idle or once the vehicle reaches a desired speed and throttle application is only maintaining speed.

The noise appears to be coming from the passenger side of the engine and is not a pre detonation knock. I've put in 93 octane fuel and a bottle of 104 octane boost just to ensure that it is not a pre detonation issue.

The noise sounds as though it is "oil muffled", if that makes any sense. In other words it is not a dry metal on metal banging or clanking, it's more of what I would describe as a clatter.

I've read about issues with push rod cups on rockers coming loose and rattling, but I would think that noise would be present in all conditions, not just under acceleration. In addition, if it were a collapsed lifter, I would think that the noise would be present at all times.

Has anyone experienced something similar, and if so, can you point me in the likely direction of the culprit?

There is no accompanying oil pressure warning light or any other indication that the vehicle is having mechanical failure.

 

Hi,
I have owned a Discovery I since 1997.
When the engine is just started for the day - after sitting all night.
You go to drive "D" and are just putting on the gas - there is a chattering noise. Has been there for many many years. This noise all but goes away when the engine reaches operating temp. In fact it for the most part does go away.

The Discovery II I recently bought - 2001.
The same exact chattering noise. Only not nearly as loud. But the exact same noise.

Must be a characteristic of the engine.

I have never worried about that noise at all.

It only is present under light acceleration when the engine is first started in the morning. Never any other time.

It would be interesting to know what it is.

 

In my case, the noise never goes away based on engine temperature. It is present under acceleration at all times. The noise subsides at idle and any time a desired speed is reached and maintenance throttle is being applied.

I read somewhere on the forum that a secondary air valve might possibly cause a clatter like this, so perhaps that is a place to start...

I will investigate that ASAP.

 

The SAI noise which comes from one of the two SAI valves not operating is a muffled exhaust leak burble sound present at idle and all other times. The other SAI noises mostly go away after the pump shuts down within a minute of a cold start.

 

Sounds like it might be an exhaust rasp, maybe. This maybe stupid, but did you drop a socket or tool down in the engine compartment? Forget to put a nut or bolt back on and maybe it dropped onto the headers? I had a chatter for 2 days, drove me nuts as I searched and searched for it. Finally, I found the source- I left an empty can of PB Blaster behind the air dam for the heat/ac. Ooops.

 

No loose tools... Suppose it could possibly be an exhaust leak, but it doesn't sound like it.

It sounds a bit like lifter clatter, but it is only present under acceleration.

It doesn't go away after warmup.

You can't hear it at idle.

You can't hear it under maintenance throttle conditions.

It is most prevalent above 2000 RPM, but only under acceleration.

Appears to be coming from the passenger side of the engine bay.

I have no warning lights present at all...

 

The SAI is in the rear left corner, behind and to the right of the fuse box. That seems like the general area of the noise you describe. My heater/a/c fan makes a funny ticking noise under acceleration when the heat/a/c is on, thats located behind the glovey. Might also be a stuck air flap for the heater/a/c. I had a car once that made a plastic-like chatter noise b/c the air flap was clogged with junk. That's also located behind the glovey. I think there was a guy on here that described his stuck air flap as making a "farting" noise.

 

Upon further investigation tonight, I'm relatively sure that the noise is coming from the rocker arms on the passenger side closest to the firewall.

Looks like I'll be pulling the valve cover off and have a look see...

 

Can you post a quick video if you can safely take it?

 

It ended up being an exhaust manifold gasket leak on the passenger side. Went ahead and replaced all gaskets on both side.

It's nice to be clatter-free... It no longer sounds like I'm driving a diesel when I pull away from a stoplight.