Question - Engine noise

[fm]

Hi.

It seems that experienced m42 owners are talking on this forum.
So I hope one of you guys will help me.

Has someone ever heard such an unpleasant noise coming from the inner part of a M42B18 ?

http://www.youtube.com/watch?v=7OhiKwDOuaU

First, a little noise appeared at 3000 rpm one year (5000km/3100Mi) after I bought the car.

The previous owner changed the chain tensioner.

18 months later - today - the noise has increased significantly.
Another noise is now present under 3000 rpm during deceleration and the engine has become noisier above 3500 rpm.
Since a month, the idle is rough a bit like a big twin.

From the beginning, the main noises - those you can hear in the video - appeared only when the engine was warm. Now I can hear them even when the engine is cold.

When the car is stopped the noise seems to come both from the exhaust and from the top of the engine - resonating in the intake manifold.

So I changed the whole exhaust line from the manifold to the silencer but that didn't solve the problem.

However the power is still there and the engine is able to accelerate from 1000/1200 rpm in 5th gear.

I guess the timing chain or the flywhell bearing is worn. Or both ?

Are the timing chain sprocket teeth in good condition ?



Thanks for the advices.

[keflaman]

Hello and welcome to the forum.

I can't tell anything by the video, but the teeth on your timing chain sprockets are definitely worn. The M42 engine is fairly noisy as far as engines go and I've been asked twice in the last month by non-BMW enthusiasts if my car is a diesel.

 

[fm]

Hello.

Thanks for the reply  .

The noise of my engine is not exactly the same but very similar to this one :
www.youtube.com/watch?v=-FpGTCaiioc

I know that the M42B18 can be noisy without failure or fault.
But mine was not noisy/vibrating when I bought it in 2012 -12000 km / 7500 mi less than today.

This is why I think it is faulty now.

I noticed other details when I removed the cylinder head cover :

The two camshafts are slightly shifted (right word ?) towards the right side = the chain side.



The camshafts are not perfectly aligned. What is the tolerance ?



Could this explain the noises and vibrations ?

[keflaman]

By no means am I an engine expert, but I would suspect your noise is from extremely worn timing chain components. The pointed timing chain sprockets is one pretty good indicator. If you have a mechanic's stethoscope, use a wooden dowel held against your ear and probe the surface of the engine. You can pinpoint the area of noise pretty accurately and diagnose from there.

As far as your "cam shift" question, I don't believe that has any significance in regards to your concerns.