Rattle/Tick On Cold Startup

[Caleb]

I've noticed a noise when I cold start my engine. It makes a distinct rattling or ticking noise when the engine is first running. It seems to last about the same amount of time as it takes for the engine to go through the catalytic warm-up stage: RPM's are slightly higher and the valve timing is changed.

I know its not the normal injector, or valve train noise, because I know what that sounds like, and those noises don't go away.

I really don't want to take it to the dealer and say "it makes a rattling noise", because I know they hate stuff like that, and it only seems to be on cold starts. So hard to reproduce.

I did do a little research, and I think the noise may be related to the hydraulic tappets (http://www.realoem.com/bmw/showparts...70&hg=11&fg=25 #7). Because on a cold start, there may be no engine oil in the tappets, and there would be a slight spacing between the tappet and the roller-rocker arm, causing the noise?. Then once the tappet fills with oil, the spacing is eliminated, and the noise would be gone?

Has anyone else noticed a noise similar to this? Or know if I'm right about the possible cause? I believe the user Mad Dragon is a service technician, and maybe he could chime in?

[KingOfJericho]

The ticking is common and most people claim it's normal.

[randomquickness]

it may be the start of waste gate rattle (very common with the N54)

[Caleb]

Originally Posted by randomquickness

it may be the start of waste gate rattle (very common with the N54)

I've seen the SIB on the wastegate rattle, and it says it happens while decelerating. I'll pop the hood and listen closer on the turbo side on my next cold startup.

[randomquickness]

yes, mine rattles on deceleration but it started rattling on start up before that ever happened.

[NewYearsBoy]

Mine sounded like it was from my exhaust.... but ya kinda normal..

[MFIZZLENYC]

To me it resembles a bad vanos rattle but it goes away on warm up so i think its normal...

[Caleb]

Originally Posted by MFIZZLENYC

To me it resembles a bad vanos rattle but it goes away on warm up so i think its normal...

Yeah, that might be it too.

Yesterday I popped the hood and listened close, and it's pretty loud. It seems to come more from the exhaust side of the engine rather than the intake side, but that might be because there is less stuff blocking the noise on the exhaust side.

I'll probalby just record a video/audio with my phone and take it to the shop.

[randomquickness]

my money is on waste gates! be sure and update us!

[adrean8j]

Originally Posted by Caleb

Yeah, that might be it too.

Yesterday I popped the hood and listened close, and it's pretty loud. It seems to come more from the exhaust side of the engine rather than the intake side, but that might be because there is less stuff blocking the noise on the exhaust side.

I'll probalby just record a video/audio with my phone and take it to the shop.

Did you ever fix this or find out what happened.

[Dackelone]

Originally Posted by MFIZZLENYC

To me it resembles a bad vanos rattle but it goes away on warm up so i think its normal...

I think this sound is normal too. I did notice when I switched my oil type from Mobil-1 0w40 LL1, to German Castrol RS 0w40 LL4, the clicking sound was much smoother & less. Not as loud or metalic-like as before with the Mobil.

Q). What kind of oil are you using? When was it last changed?

I have already changed my car's oil one more time (again with G.C.) and I really think it had alot to do with the oil type on a cold (startup) engine. Some of the noise I think is direct injection and some is exhaust related. Normal in my book.

[Caleb]

Originally Posted by adrean8j

Did you ever fix this or find out what happened.

I had my car in for a Service Engine Soon light, and I also raised this issue to the SA. They kept it overnight to fix the issue and said they would cold start it to listen for the sound. When I picked up the car, they said that the sound was normal. I don't think there is much more that I can say to them.

Oil type was mentioned above. I performed a break-in oil change myself using the regular BMW Long Life 5W-30 at 1500 miles. And last week my car said I was down a quart, so I went to the dealer and got another quart of Long Life 5W-30. I added half, warmed up the engine and the computer still said I was down a quart, so I added the other half. Oil gauge then said I was normal.

I still hear the sound on cold starts.

[adrean8j]

It is the wastegate actuator arm. I have a Procede and it there is a parameter to change
The wastegate compensation. I progressively adjusted it down. ..according to Shiv's documentation some models (2008 and earlier) need it adjusted to 40-50%. I did it this afternoon and voila no rattle. Hope this helps.

[Caleb]

Ok, an update on this. When I had my car in for the recall fix I asked about this noise again. I was able to get a technical explanation from the service foreman. Here is what he said:

"The wastegate is closed by vacuum and the electronic pressure valves. The vacuum pump takes just a little while to create enough vacuum to fully seal the wastegate as well as the DME delays the full closing of the wastegate on startup to allow the wastegates to rotate, thus cleaning the valve and seat area. The noise is loudest and lasts the longest on a cold start due to the non-expansion of the wastegate components."

[dc503]

I had the same exact issue on my 335i...I received a similar explanation, though not as detailed. In the end, my SA and tech continued to advise there was no action to take until I had the deceleration rattle.

[Dackelone]

Originally Posted by Caleb

Ok, an update on this. When I had my car in for the recall fix I asked about this noise again. I was able to get a technical explanation from the service foreman. Here is what he said:

"The wastegate is closed by vacuum and the electronic pressure valves. The vacuum pump takes just a little while to create enough vacuum to fully seal the wastegate as well as the DME delays the full closing of the wastegate on startup to allow the wastegates to rotate, thus cleaning the valve and seat area. The noise is loudest and lasts the longest on a cold start due to the non-expansion of the wastegate components."

Ok, sounds like a fair explaination.

BUT... I really noticed that my engine makes much less noise on cold starts using German Castrol RS Edge 0w40 LL-4, than with Mobil-1's 0w40 LL1.

Yes, the noise does go away after a minute or two. But now its not nearly as loud as it was when using Mobil-1.

[RPM90]

Originally Posted by Caleb

Ok, an update on this. When I had my car in for the recall fix I asked about this noise again. I was able to get a technical explanation from the service foreman. Here is what he said:

"The wastegate is closed by vacuum and the electronic pressure valves. The vacuum pump takes just a little while to create enough vacuum to fully seal the wastegate as well as the DME delays the full closing of the wastegate on startup to allow the wastegates to rotate, thus cleaning the valve and seat area. The noise is loudest and lasts the longest on a cold start due to the non-expansion of the wastegate components."

Barring any of the other explanations as being the cause, and since you say you hear the noise loudest down by the exhaust side, it may be possible that you have a heat shield that might be a bit loose, and as it warms and expands, it stops.

On many new cars there is also a distinct metallic "tinking" noise, which is caused by the exhaust system metal contracting as it cools.
Maybe you have this in reverse, where it makes a noise when it's cold and then stops. Just a suggestion.

Tappet's are usually heard on the top of the engine, and do tend to stop once oil pressure goes up.
Have you tried an automotive stethoscope, or a long big handled screwdriver will work, to listen to where the sound is loudest?
That can help you locate the point of the sound.

To use the screwdriver, simply put the bit end on the engine, as the suspected point, and place your ear on the end of the handle, and listen.
Move the bit to different locations.

WARNING:
Do not do this with long hair, or while wearing a tie or other loose clothing that might get caught in the engines whirly bits.

[3k1n]

So is there a fix for this rattle? or is this something you just have to live with? Mines usually happens up until the car is up to operating temperature.