Resolved: M42 louder after installing new timing chain components

[Tech X]

Problem: After replacing timing chain components on M42 engine louder after warmup.

Attempted resolve: The detent clip from the tensioner had worked itself out of its groove and was causing friction, not allowing the tensioner to work properly. The driver side guide rail was broke. The tensioner, guide rails and gaskets.were replaced. The tips of the cam gears and crank gear and sprocket were rounded with no sharp teeth. The chain was solid and showed no sign of wear. On reassembly the cam gears were aligned as per Bentley and rotated the engine by hand numerous times, triple checking the arrows on the cams, the alignment of the rear cam lobes and timing with top dead center. I then attached the lower timing cover and the crank pulley, and poured some fresh oil on everything, and spun the engine with the starter. I took the crank pulley and timing cover back off and rechecked the timing marks with TDC. All marks lined up, everything looked good and the chain was taught. I then reassembled everything in the engine compartment and thought it was ready to go. When I started it it sounded great, perfect idle. After it warmed up, I brought the engine to 3500 rpm's to give the new tensioner some oil pressure. Engine was quiet and smooth, so I took it for a gentle drive. Unfortunately after 10-15 minutes a diesel sounding noise appeared. I removed the valve cover, rotated to TDC, used the flywheel locking tool and rechecked my timing marks. Cam timing was correct, nothing had moved, and the chain was tight as it should be.

Additional: After the above I checked for exhaust leaks and found none. I check my hoses and found no leaks, no bad lines. I was getting good circulation in the coolant system.

Anybody have any hints, suggestions or leads? After brainstorming I thought maybe oil pump or oil valve, but the temperature isn't getting hot.
Speculations: ignition coil? fuel injector? DME?

Any help appreciated. Thanks very much.

[bmwconnect]

Sounds like oil pump or Oil pressure is the problem

[DesktopDave]

I'd be strongly tempted to check the timing chain idler gear if the noise seems to come from the front of the engine.  The bearing has a tendency to die, in a worst case scenario they'll even snap the mount off the inner chain case.

Number 11 in this diagram.

Also, have you checked the lower oil pan bolts recently?

[Tech X]

Thanks. Oil delivery might be part of the problem.
I checked the oil filter last night and found tiny bits of plastic through the filter. I drained and changed the oil and filter and added a half a can of seafoam. After driving it around for awhile I changed the oil and filter again, and took it for another test drive. The noise was notably diminished, but not gone.

A forum search brought up a possible valve under or in the oil filter housing but I can't see it on realoem. Does anyone know of this or any other reachable oil blockage areas that I can address?

[Tech X]

Update: Situation resolved.
In the past week ran the engine with a mixture of oil and CD-2 cleaner.
The engine was flushed, drained and refilled with this mixture four times, each time with a new oil filter.
After looking at the photo of the broken chain guide it appears the pieces became wedged in between the rail and the chain. This wedging most likely resulted in a "cheese grater" effect, as the chain rotated it must have shaved off little pieces of the plastic. As these tiny shavings fell down they mixed into the oil pan. Their presence in the system created a bit of temporary oil starvation. The first two oil and filter changes showed the shavings, but the third and fourth filter changes were clear. The car now sounds like a typical chain driven M42 engine.

Thanks again for the input and helping to narrow down this problem.