I know this will be a guessing game but I'm out of better ideas. I rebuilt the 4.6 engine in my DII about 6k miles ago. Been running great with no issues until about a month ago on my way home it started making a loud clattering noise. When I rebuilt the engine it got a sleeved block, new cam, tappets, refurbished crank, oil pump, all new bearings and pistons. It runs great, uses no oil, doesn't smoke but especially at idle there is a very loud clatter. First thought was lifters so I pulled the top end and replaced all the lifters with new oem style lifters from Atlantic British. Didn't see any issues with the ones I pulled. They were all pumped up and had zero wear. After all that the noise came right back. Next I pulled the oil pan and timing cover. Some of the rod bearings were worn more than I'd prefer so I replaced them all with new and new bolts. Checked the oil pump and it was in good shape as well as the pressure relief valve. Put it all back together today and same exact noise.

It only occurs when the engine is fully up to temp. Not even idling for 15 minutes will cause it. The noise is worst at idle and under light throttle. When you go heavy on the throttle or if you hold the brake and put the engine under load it goes away. Even while making the noise it seems to be running smooth and has the same power it always has. If it sits for 5 or 10 minutes and you start it up the noise is gone until it builds some heat back. I talked to a reputable rover mechanic near by and he thought it was lifters still. I just think it would be a MAJOR coincidence for it to make the same exact sound with all new lifters. My only other theory is a sticking valve or a weak valve spring. When I did the lifter job I motored the engine over on the starter and everything functioned smoothly. I'll try to post a video of it idling in a few.

 

Hopefully the video will come through

 

Have you checked the oil pressure? Measure the exact temperature the clatttering starts. What rpm does it go away at if you rev the engine?

Three things cause clattering on a D2 engine:
1. Slipped liners
2. Valve train noise (usually low oil pressure due to walked cam bearing or broken oil pump)
3. Rod knock due to low oil pressure (see #2).

 

I have not checked the actual pressure. I know the idiot light works and is set to 7psi according to rave and minimum oil pressure is supposed to be 10. I’m doubtful it’s an oil pressure problem. It doesn’t go away with RPM, only engine load and temperature. It’s not Rod knock because I just put fresh bearings in and inspected the oil pump gears. If it was oil pressure related I’d expect to hear it on a cold start but I don’t.

 

Once it starts clattering I can rev the engine in neutral and the noise persist at all RPM. If I put it in drive and hold the brake and accelerator the noise goes away until I let off the gas.

 

So the frequency of the clattering increases with RPM? If it goes away with load I am going to get cracked flex plate or bad torque converter.

 

Correct in the frequency. I replaced the flex plate when I rebuilt the engine. I looked at what I could with the oil pan off. Can’t rule it out but the sound really seems like it’s in the engine.

 

I have some annoying knock in the block as well - slipped liner. It was kind of hard to tell where it's coming from. Here is my ghetto diagnostic procedure.

​​​​​​Get obd reading of your engine RPM at idle. Divide by 60 and multiply by 10. Record a clip of your engine. Trim video to exactly 10 seconds. Slow down the video to 50%. Count the knocks. If you are counting half as many knocks as rotations of crank, then it's ur valve train. Same number of knocks is ur rotating assembly, flex plate or tc.

 

I had a clatter that, like yours, did not appear until the engine came up to temperature. Turned out, surprisingly, to be the exhaust heat shield, not an engine thing at all.

 

That's a good idea. I previously had tried downloading a noise app hoping it could determine the frequency for me. Never thought about slowing the video down enough I could count the knocks. Thanks.