I'm in the midst of diagnosing timing chain rattle on my 4.0L LR3. There was some initial rattle when the engine started and it would go away within a couple of minutes. So I did an oil and filter change - I also used a flushing agent before removing the old oil. After the oil change the rattle was there all the time!

I changed both front and rear hydraulic timing chain tensioners and the noise went away. The engine was running really quiet. Initially I think it was just the front chain tensioner failing, because the rear one was quite firm and changing that did not resolve the problem. Only after changing the front tensioner, which wasn't anywhere near as firm, did the rattle noise go away.

I was very pleased with myself, however a day or two later the rattle returned and sounded worse than ever. I think both chains are now rattling! This makes me suspect there is an oil flow problem to the tensioners.

I'm about to drop the engine oil sump pan to see if there is any timing chain cassette debris in there and to inspect the oil pickup. It also occurred to me that the oil pump may be worn/failing, but there is no oil pressure gauge on this vehicle, presumably just an oil pressure switch.

Does anyone know where I can attach a physical oil pressure gauge to the engine? and if so what pressure I should expect to see?

 

Have you tried a different grade oil like 5w40 ?

 

No I haven't, I'm using 5w30 (Castro Edge fully synthetic), however the rattle is instant as soon as the engine starts from cold, so a 5w40 shouldn't make any difference because both oils have the same viscosity at low temperature.

 

I discovered a lot of debris in the mesh screen in oil sump pickup tube that goes to the oil pump, including some bits of what I suspect is one of the timing chain cassettes. There would certainly have been enough crud to impede oil flow, and as the hydraulic chain tensioners are at the top of the engine if the oil pressure was a but low as a consequence I can imagine it would affect the tensioners.

Unfortunately there is a small crack in the bottom of the pickup tube. It's not big enough to cause an issue at the moment so I'm going to try to repair it with a wicking superglue to prevent or at least delay it getting worse. Ultimately it's going to need replacing, but I can't find a new one locally and I can't await for one to come from the USA.