911T - any thoughts on engine noises. Main bearing?

[RobFrost]

First real start and run of my newly acquired 2.2 911T - here's a video (click the speaker to unmute). I took this within about 1 minute of a cold start. It's been running within a couple of months and has new oil, leads and plugs.

https://photos.app.goo.gl/bmEra73MHUFi2pjt8

Any thoughts or comments? I'm a complete noob so have no idea how normal it all sounds, really.

If you listen carefully to the first five seconds there's a low-frequency knocking noise. What's this? Is it the main bearing? I moved my phone around a bit to give an idea how the noise changes. If you listen at the very start, that knocking noise is the most obvious thing and it's a bit deeper in tone than it comes across in the video - more of a "knock" than a "tap". It's fairly audible in person, I think it's a bit too low-frequency for the phone's microphone to pick up.

There are a few pops which seem to be backfires through the inlet valves and after a few minutes, a healthy misting of blue oil smoke surrounded me.

Obviously it will need to be seen by an expert but I'm looking for any first impressions before I compression test etc. The big question is, am I looking at a rebuild?

[PMNorris]

I couldn't hear any obvious noises that I would be concerned with. I would start with valve adjustment and a tune. Mine has quite a noisy clutch bearing. Does the noise change if you dip the clutch?

[chris68]

Sounds pretty normal to me too. Those Webers probably need setting up. Sounds like they're spitting back which suggests some throats are running a bit lean on idle circuit. 911 bottom end is very robust so unless abused doesn't normally give trouble.

Can help with setup. Give me a shout if you're stuck.

Cheers

[RobFrost]

Sounds pretty normal to me too. Those Webers probably need setting up. Sounds like they're spitting back which suggests some throats are running a bit lean on idle circuit. 911 bottom end is very robust so unless abused doesn't normally give trouble.

Can help with setup. Give me a shout if you're stuck.

Cheers

Hey - you're nearby! I assumed the spitting back was leaking intake valves, no?

Let me know if you're in the vicinity to have a listen to this knocking noise. Also, it's burning a lot of oil so top priority for now I think is a compression and possibly a leak down tests. Carbs may be a bit further down the road.

[Bruce M]

I can hear a knock (barely) when you move to the left side. Might be low pitch sound and mostly rolled off due to microphone range.

If much clearer/ louder in person, it might be rod knock.

Use a mechanics stethoscope, or a long screwdriver at your ear, to hear it better. Just don’t get it caught in the fan belt!

[RobFrost]

I can hear a knock (barely) when you move to the left side. Might be low pitch sound and mostly rolled off due to microphone range.

If much clearer/ louder in person, it might be rod knock.

Use a mechanics stethoscope, or a long screwdriver at your ear, to hear it better. Just don’t get it caught in the fan belt!

It's quite loud in person and most audible when you close the lid and step back a bit. Low pitch, like someone knocking on an oak door with their knuckle. Supposing that's rod knock, is it best not to drive too far and it requires a bottom-end rebuild, right?