[djrule]

Hi Guys

I have this really weird noise being produced around 2k-4k rpm on the N53 engine. E92 330i manual 100k miles. No error messages.

On a cold start there is a really loud rattle that occurs under light load at around 2k rpm. This only happens for the first minute of engine startup then disappears until the next cold start.

But there is also a damped metallic ringing sort of noise around the same rpms that exists always. Under load and when coasting.

See video below at 0:15 and 0:24

Any ideas?

[E92William]

Wait what I've never heard this one before lol. I'd be inclined to say it's a disa valve flopping around but not all n53s got that manifold and it doesn't sound like one when it breaks off. Have you tried this with the serp belt off? I don't think it's something as serious as a timing chain or whatever or you'd have vanos codes but I wouldn't rule that out. You could also have something like a broken piece of catalytic converter material in the exhaust manifold, try tapping it and hear if anything seems to be moving jnside. I'd also check all intake connections for anything loose or unseated.

[djrule]

Originally Posted by E92William

Wait what I've never heard this one before lol. I'd be inclined to say it's a disa valve flopping around but not all n53s got that manifold and it doesn't sound like one when it breaks off. Have you tried this with the serp belt off? I don't think it's something as serious as a timing chain or whatever or you'd have vanos codes but I wouldn't rule that out. You could also have something like a broken piece of catalytic converter material in the exhaust manifold, try tapping it and hear if anything seems to be moving jnside. I'd also check all intake connections for anything loose or unseated.

Yeah weird one eh. Im gonna have to give it a go without the serpantine belt. My manifold is the 3 stage one so will have two disa valves. I doubt they are broken. When accelerating I can feel when the disa valves move.

This might be a long shot but it sounds to me like a jet of liquid hitting metal. maybe the injectors have a bad spray pattern and are hitting the pistons or engine wall? but surely the engine wouldn't run nicely and would throw codes if this was the case?

Could the rattle on a cold start be knock?


Inpa shows my vanos adaption for intake and outlet in the red, around 15 for both. Loose timing chain?

https://bimmerprofs.com/wp-content/u..._positions.png

Thanks for the help!

[E92William]

Give it a try without the belt it's not a hard job to take it off and back on. I think we're looking at some chain or actuator issue with the vanos actuations behaving like that though, who knows maybe it's just not getting oil up there from clogged check valves though this is a very long shot.. I don't think if it was injectors you'd have a relatively smooth running engine at all.

The chain tensioner is easy to replace at least the one on the side of the engine and fairly affordable

[djrule]

Originally Posted by E92William

Give it a try without the belt it's not a hard job to take it off and back on. I think we're looking at some chain or actuator issue with the vanos actuations behaving like that though, who knows maybe it's just not getting oil up there from clogged check valves though this is a very long shot.. I don't think if it was injectors you'd have a relatively smooth running engine at all.

The chain tensioner is easy to replace at least the one on the side of the engine and fairly affordable

Sorted! I replaced the cats as they were coming up with inefficiency errors, but while I was that deep into the engine I made sure to tighten everything up properly. I did notice that one of the intake jubilee clips was slightly loose so I tightened that up.

Not sure what sorted it, but its sorted. Sounds so much better without that constant ringing.

When the N53 is running right it is such a lovely engine.

[E92William]

Maybe it was some piece of cat broken off inside them:either way it's good that it's fixed!