skratch77

Just asking if this is something to worry about.I just bought a 13 p31 car with 25k miles on it and it makes a almost knock noise on cold start up and goes away completely in 2 seconds right after start up.

It almost sounds like a pulley or tentioner from the out side and slight knock for a split second from the inside.

The car will also do it after a 10-15 min cool down and start up again.

I just had the dealer change the oil and that did nothing to help.is this normal or something to worry about?

m a x i m u s

Possibly one or more of the 4 cam adjusters. Had mine replaced, but my tech told me it's nothing to worry about. True or not, though, I can't be sure.

skratch77

I will call and schedule a check up on it.the car sound perfect after 2 seconds and don't want to open a can of worms with lifter tick if they start doing work inside

m a x i m u s

Let me know what they say, especially in regards to whether or not bad cam adjusters will ruin an engine's internals.

skratch77

I will and is the cam adjusters a typical issue with these cars?

This is new to me coming from an e55

m a x i m u s

Not sure if it's common, but a few members here knew what it was straight away when I posted the problem.

skratch77

Do you have a video of your issue so I can listen to it to

m a x i m u s

No

XZACM102

I have also 13 P31 with the exact same mileage and such noise on cold start up. Your car seems to be heavily modified though.

C63amg Tokyo

Definitely not normal, however - you're going to get a ton of guesses since you haven't uploaded a video sound clip or anything. One mans description of 'knocking' could be another's banging or ticking. It sounds like a cam adjuster to me too but it's just a guess. If u have a warranty, don't worry about opening up a can of worms, get the problem resolved. Good luck and hope it's nothing serious. Also welcome to the c fam

skratch77

I will make a video now.I just hate doing cold starts as I put the car away for the winter and my car is not modded I just bought it cpo 2 weeks ago from the dealer.

Only thing it has is renntech tune and had renntech airbox. (My dealer is a renntech dealer).its 25 degrees out so this will be a truly cold start.

skratch77

Go figure I start the car in negative degree weather and its a perfect start.

Car has been sitting 2 days and it started 100% perfect this morning.

skratch77

Here is a video of the rattle

m a x i m u s

I'm having a hard time hearing it clearly bc of the exhaust at start up, but it sounds a bit different from when my cam adjuster(s) went bad. Of course, I heard mine from inside the car with the hood closed. Are you sure it's from the top of the engine? Maybe it's a heat shield?

Edit: actually after listening a bunch of times, it does sound like a bad cam adjuster.

skratch77

It's a lot louder in person and is definitely from the top of the engine.it will only do it after 30 min cold starts and not every start does it.

I will take it in and see what they say

Jasonoff

That's the cam adjuster.

This one is even worse. EDIT: Start it at 16s.

skratch77

Ok so is this a known issue? I just dropped 60k on this car and now I'm worried about it long term.

Also am I going to have a hard time getting the dealer to fix it? Im pretty sure they will say its normal

roadtalontsi

yep thats definitely an adjuster. Known issue? well like any other part sometimes they fail at times. It has to do with oil pressure bleeding down inside the adjuster. If you just dropped 60k$ your car should still be in warranty and shouldn't be an issue to get fixed. just show them the video. Worst part is getting the shop to duplicate it and figure out which one of the 4 it is.

skratch77

Yes it is a cpo and I purchased another year so I have 3 years total warranty on her.

I will call the dealer Monday and see what they say.

It was 60k all in with extra cpo and taxes etc.the car final sale price after going back and forth was 54k.they were asking 59k for it.

It's a 2013 white coupe with 25k miles
Carbon pack
Development pack
Xenons
2 tone red and black leather
Limited slip
Lane tracking/blind spot etc

I think I could of got it a little less but I spent almost 2 years looking for this color and option combo

AMGonFire

Lot of these motors make this noise common issue dealers have no idea what it is listened to 3 diff cars on their lot made the same noise as the video. mine makes it as well had the cam adjusters replaced guess what it will not fix your problem there have been a ton of posts on this noise recently. The end result for me was 4 times to the dealer diff ones too replaced cam adjusters end result said was normal and basically deal with it wont cause any harm cam lobes looked great too FYI

2012
30k miles
Been driving with the same noise occasionally on start up for 6k miles no problem side note change your oil seemed to improve the sound significantly

AMG893

OP, the 2nd vid you posted, its not my imagination is it. But a put of smoke came out of your air intake boxes??

m a x i m u s

That's strange, I do see something there. Maybe it's air going in? As in, maybe the engine sucks in air so violently at cold start that it somehow affects the pocket of air that's getting pulled in? That is weird. Or maybe it's a normal puff from the engine, but I would imagine the air flow would be inward at all times when running. I'm not an engine guy by any means, though.

8o8is

It looked like a visual effect of his headlights turning on at startup. OP's second vid is cutoff at the edges, so it's difficult to see. Also seen in his OP's first vid.

skratch77

Guys it might be the lights moving up and down on start up!

roadtalontsi

No that noise is not normal. Why does my car not make it? If it's still doing it then you got bad new parts, or they replaced the wrong ones. The only time this or a lifter tick should happen is if your car sat for a long period of time - like weeks. Find a different dealer.