Hello, I have a 2000 XK8, after the engine is warmed up there is a LOUD rattle coming from where the tranny meets the engine, I listened to another XK8 and heard the same rattle but much more faint than mine (barely noticable).
It is only at idle, as soon as you give it gas it goes away. Is this a common rattle for this 4.0 or not, I cant seem to grasp what the sound may be coming from, thank you in advance for any feedback.

 

Haven't heard this myself yet, but it might be catalyst issue (so parts of the catalyst loose). You will be able to pinpoint exactly where the noise is coming from with a stethoscope. It may also help here if you record the sound.

 

I added a video of the noise on YOUTUBE here is the link:

 

A bit hard to tell but I would agree with Avos, you have a cat brick problem if it goes off when you rev the engine then comes back on the over run them definitely cat brick

 

Here's an update: got a stethoscope, and we can eliminate the cats as the problem. The rattle is definitely loudest at the bellhousing or the front of the transmission.

To summarize other symptoms:

1. Only rattles once warmed up and the engine is at low idle (~600 rpm on the dashboard tach). The noise goes away once the engine is revved above 800 rpm.
2. The noise goes away when the transmission is put in gear.
3. The transmission shifts normally.
4. No OBD II error codes.

Thanks again in advance for any insights.

 

Was this rattle ever diagnosed. My XK has developed a similar rattle. Transmission is working fine. Going to change the oil and filter soon so maybe if if is transmission there will be shrapnel!

 

No I changed the torque converter just because everything was pointing to the transmission and the noise was loud at the front of the tranny still no luck I believe the noise is the pump going out, we will see, it did not quiet down much after changing the fluids.

 

Did you ever fix it?

 

You have low transmission fluid ...I and others have had that noise..I drained out 3.6 litre of fluid and replaced it with 6 litres .....New filter /new fluid required . The torque converter is short of oil and making that noise.

 

I have a similar problem and rattle which seems to come from the Torque Converter…

• sounds like marbles in a can - made me wonder if it was baffles.
• is there from cold startup and doesn’t really go away.
• Gets much worse when A/C is engaged or other electrical load is on
• disappears when driving or revved over 1500rpm.
  
• no codes, transmission is perhaps a little slow to engage but mostly behaves other than some surging @ 50mph UNLESS in sport mode.
  
• if car hasn’t moved for a week or so - it will crawl fwd in D or backward in R for a few min. Like it’s building up pressure or recirculating fluid.

She’s parked in the garage now so I can take my time and hopefully figure it out. I was going to start by switching out the Torque Converter but reading this thread it seems that might not be the solution! Part of me is tempted to just order a whole rebuilt transmission for $4k but the resulting divorce could end up costing even more… 😖