S52 Rattling Like Mad!

[iStagl]

Let me start off by saying that yes, I have searched, and yes I am familiar with these engines. I recently rebuilt the timing system on my 328is and the VANOS system. I recently sold that car.

Just two days ago I picked up an E36 M3 sedan (in techno Violet, for what it's worth...) I got it cheap because it is likely it's going to need an engine due to scoring on the cylinder walls of cylinder 1 & 2. That's for another time, though. It has somewhat low compression in those cylinders but frankly seems to have plenty of power still minus the occasional puff of smoke out of the tail pipe.

While accelerating, it has a WICKED rattle under load. It starts at about 2k rpms and continues well up into the Rev range, eventually dying off near 4500rpms or so. Lot's of surging throughout this, as well as a code of VANOS stuck (mechanical). Don't have a specific code value at this time. Just wanted to see if this noise sounds familiar to anyone. It's unlike any VANOS rattle I've ever heard. It also comes on, let's say, if you're cruising 50-60 mph steady and start to go up hill, which I assume would be when VANOS would try to cycle to allow for more torque.

I guess what I am asking is, by the crazy sounds this thing is making, should I bother messing with this unit or just source a good unit? The previous owner had a new head put on this car with all new valves, and a used VANOS unit IIRC. Where should I begin my testing?

I am also curious if this is potentially the sound made by not catching the very first tooth whilst reinstalling the VANOS unit onto the camshaft. I've never heard what that would sound like.

Also, the car threw a crank position sensor code this evening and started falling on it's face BAD. Any throttle over 2k rpms would result in immediate falling on it's face and acted as if the engine was cut off. I know the typical thing to do would be to replace the CKP sensor. The PO replaced it with an aftermarket unit and left the OEM unit in the box of the new part. Replaced with a HELLA brand. My question to this is, can a potential VANOS fault be screwing with the CKP sensor to the point where the car is thinking it's getting a bad reading? I don't want to start throwing expensive CKP sensors at it, if it is being caused by something else.

Thank you for your time, and I linked a video of the wicked rattle from the engine. It's a bit hard to hear, especially at first because it's Rattling right as the video starts, but you'll hear it stop when I let off the accelerator. I press the gas twice more before the end of the video for two short bursts and immediately it starts Rattling again.
Tomorrow, during daylight I will get a video of the cold start noise as well as a better quality video of the rattle.

[Eric93se]

Check the engine and trans mounts, they could be shot or hard mounts (aftermarket). As for the damaged cylinders, I recall that if the upper timing tensioner goes bad it can leak pressure.

Knowing that they put a used vanos is not enough info, you need to know if it was rebuilt.

Test your fuel pressure. Clean all your wheel speed sensors. Pull your fuel rail and check to see if your injectors are leaking.

Get the SRS reset/scan tool:
https://www.ebay.com/itm/B800-Diagno...n/202463823392