Seeking opinions on S54 noise

[scmtx]

2004 e46 s54. Motor was rebuilt around 10k miles ago. Just started this “knocking” with a cold start the other day. Goes away when car warms up. Need to adjust valve shims, cam sprocket bolts, or something else? Thanks in advance for the help.

https://youtu.be/Tk_aXXmZhUs

[lemoose]

sounds like an S54 to me. the sound doesn't get louder if you give it some gas does it?

[maupineda]

It does sound a bit rough. How many miles on the oil? Since we don't have hydraulic lifters , i doubt is the valve train, valve adjustment is more of a tick noise, not knock/tap.

i never liked 10w60 as it gives rough cold starts, i prefer 5w50 or 0w40 with ceratec. It does make a difference on smoothness on cold and the ceratec thickens the oil a bit.

[Pklauser]

I've got a similar sound. In my unprofessional opinion it sounds like piston slap, which in my equally unprofessional experience is pretty inconsequential.

[cobra]

These engines seem to make some kinda nasty noises but as long as your vanos is bulletproofed then it shouldn't blow up.

[Pklauser]

Lol, coming from BMW M20s and Volvo B230s I've learned that unless it sounds like something really banging, it's probably fine. It's easy to go nuts with a stethoscope chasing minute sounds that everyone's motor is making but most just aren't noticing.

[sapote]

It sounded like a knocking (piston hitting spark plug tip and hopefully not the early rod knock), not slapping as these pistons don't have a lot of radial plays. After 1:00 it also sounded like high pitch bearing noise -- I would remove the belts to see if it will change.

[heinzboehmer]

I would remove the belts to see if it will change.

+1. I would look at the pulleys/belts first as well.

I once forgot to fully torque the bolts on the water pump pulley and had a similar noise, albeit much louder.

[bmwfnatic]

One thing I can't help to notice is when you zoom the camera in and out the sound/volume of the "knock" we are listening for drastically changes, which would also lead me to believe this might be outside of the engine, +1 for running without fan/belts and checking if still there.

[Toby22]

I’ve got similar sound, but yours seem a bit more excessive

[scmtx]

Thank you everyone for your input. I have a shim kit coming tomorrow...so I guess I will open her up. I agree with the bearing/belt related sound, I'll pull the belts too. Probably related to whatever belt/pully sound, but the car used to/maybe still does make a high pitched belt squeal for the first .5 sec right when the motor first started.

I'm running Castrol Edge supercar 10w60...which coincidentally I changed just prior to this noise. I'm pretty sure the motor sounded "normal" on the first start after the oil change though.

If the noise is metal hitting metal, or metal hitting something....then since the noise goes away when the car warms up, is it not just the metal expanding and closing whatever gap their was? I guess most of the videos I watched, with the same or similar sound, don't go out long enough to hear if the motor quiets down. The piston slap theory seems plausible. Just doing some quick research...stock pistons are cast, my motor has JE Forged 84.5 mm. From what I have read the forged pistons will generally require a little more space in the bore for clearance....greater expansion in the type of aluminum? If any of that was true though, why would it all of a sudden start making the noise. Wear over time?

Thanks again.

[sapote]

my motor has JE Forged 84.5 mm. From what I have read the forged pistons will generally require a little more space in the bore for clearance....greater expansion in the type of aluminum? If any of that was true though, why would it all of a sudden start making the noise. Wear over time?

No noise in the previous cold winter? I don't think wear over time would suddenly cause the new noise. Do you know the clearance of this JE set?

[Arith2]

Forged pistons slap and that's what this sounds like. I'm surprised it didn't happen sooner. Forged pistons are smaller when cold and over time, will wear more when cold. The noise length of about a minute is consistent with how long they take to warm up. The good news is forged piston are softer than cast so that offsets it a bit. The silicone content is slightly higher making them better for heat and elasticity. They're also FORGED with a hammer. The tradeoff will be the wear caused because of piston slap. Unless you need forged by pushing 700+ horsepower, stock is for you. Stock internals are proven to be very robust. With forged pistons, your rod bearings won't wear as much, in theory. The only real downsides are weight, cost, inconvenience of getting internals changed, and sightly more wear. Forged are superior in almost every way.

Please don't go and put thinner oil in. That is NOT the solution. Oil additives aren't the answer either.

[Andy2424]

Have you checked the air pump and the valve to see if they are tight and if the valve is working?