slight rattling under very light acceleration

S

StevenH72

Lifer
Evening all.

So it's common knowledge that the S54 is a very tappety/ rattly engine in general.

However, I was driving yesterday and under very light acceleration, (i.e. just barely touching the accelerator) at about 1.5 - 2k revs there was a rattling noise (different to the normal tappety noise). If I put pressure on the accelerator the noise disappeared.

The car drove fine and didnt react strangely at all.

Just wondering if anybody else has had any similar experiences.

The recent rod bearing discussions have got me paranoid... :|
 
Bearing shell failure is recognised as a "knocking" noise which is in time with engine RPM and once it starts will remain thereafter. My guess is that the noise is from a loose heat shield.
 
Vanos bolts coming loose can be an issue....

Its usually shows around that RPM too....

Will it do the noise if you just free rev the car without driving it ?
 
Its probably just part of the general rattly/tappet engine type noise and you have just tuned into it now and keep trying to make it make the noise so your hearing it more and more, They would sound much quieter with a sound deadening panel under the bonnet but then you would be losing the rawness of the beasts.
 
Z4M-2006 said:
Vanos bolts coming loose can be an issue....
Click to expand...

I guess this is the other issue I am concerned about.

It disappears under normal acceleration (and doesn't seem to happen in every gear, I noticed it mainly in 4th, 5th, 6th).

I'm hoping it is just a normal trait of the engine, it is a very quiet noise and I doubt if a passenger could even hear it. I'll have a look this weekend to see if I can spot anything.
 
Shell nitro is a good fuel...

Pinking is pre ignition and it can sound like a rattle...Its usually heard when your labouring the engine a little in gear.High gear and low RPM's,then upon trying to accelerate a momentary rattle can be heard.
The S54 does pink,some more than others...Bad pinking can be symptoms of headgasket problems,common on the S54..

Is the idle rock steady or does it feel a like it has a stumble ?
 
Wouldn't happen to sound like this would it? I've still yet to get mine looked at and this noise is such a pain!

04B929B8-B257-4AFB-9A2F-DFEF48C1262C-1718-000001FDCEF01699_zpscf66b115.mp4
 
http://i1136.photobucket.com/albums/n488/xiaxio1/04B929B8-B257-4AFB-9A2F-DFEF48C1262C-1718-000001FDCEF01699_zpscf66b115.mp4
 
Xiaxio said:
Wouldn't happen to sound like this would it? I've still yet to get mine looked at and this noise is such a pain!
Click to expand...

No as soon as I start to accelerate the rattle disappears and isn't as defined as that.

Z4M-2006 said:
Shell nitro is a good fuel...

Pinking is pre ignition and it can sound like a rattle...Its usually heard when your labouring the engine a little in gear.High gear and low RPM's,then upon trying to accelerate a momentary rattle can be heard.
The S54 does pink,some more than others...Bad pinking can be symptoms of headgasket problems,common on the S54..

Is the idle rock steady or does it feel a like it has a stumble ?
Click to expand...

Yeh this basically sounds like what it is.

The tell-tale sign for head gasket problems is the gunk under the oil filler cap right?
 
No...

The S54 rarely blows the gasket into the oil or water galleries..
It always blows across the cylinders as the gasket is so thin..

You then get cross blowing of the cylinders and this pushes super hot combusted air into the opposing cylinder,overheating the cylinder.
This then causes that cylinder to have preignition..

The S54 usually stumbles slightly on tickover when the headgasket fault is present..

It's a weird fault as the pinking is the only real outward sign that something may be going wrong..but if the car is very lightly pinking under load, I wouldn't worry .
 
Z4M-2006 said:
No...

The S54 rarely blows the gasket into the oil or water galleries..
It always blows across the cylinders as the gasket is so thin..

You then get cross blowing of the cylinders and this pushes super hot combusted air into the opposing cylinder,overheating the cylinder.
This then causes that cylinder to have preignition..

The S54 usually stumbles slightly on tickover when the headgasket fault is present..

It's a weird fault as the pinking is the only real outward sign that something may be going wrong..but if the car is very lightly pinking under load, I wouldn't worry .
Click to expand...

There's no stumble, I think i'm just being paranoid.

With the potentially catastrophic issues (rod bearings, vanos etc) and the S54 being a very tappety engine I was a bit on edge.

This thread seems quite useful for me:

http://www.z4-forum.com/forum/viewtopic.php?f=9&t=29806

It doesn't sound like a vanos issue, or the other video here.

I'll just keep an ear on it to see if it changes. I'll also get the valve clearances checked.
 
Ah...

Thought u was in Yorkshire for some reason...:(

You would have been more than welcome to hear and drive mine to see if there was any difference
 
Z4M-2006 said:
Ah...

Thought u was in Yorkshire for some reason...:(

You would have been more than welcome to hear and drive mine to see if there was any difference
Click to expand...

Ah, I appreciate the sentiment anyway, cheers. :thumbsup:

Hopefully at the kent meet on 3 Nov there'll be a few MC's there I'll be listening very carefully to.
 
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