Noisy cold engine after 25sec to 130sec

[modic]

BMW M3 -1993, European modell.

The noise appear first after 25sec from cold start. The colder it is the more obvius noise, but is always very easy to hear. The noise dissapear after 120-130sec. It is located on the front exhaust side. I have really tried to find the noise around the famous VANOS in the front, but cannot locate it to it. Sounds like I am having stucked exhaust vale or something because the engine doenst run smooth during those ~100sec, the noise is like the engine would be runing on 5 cylinders, but no power problem so the firing of the cylinders seems to be OK. I have changed main chain tensoiner and tried mineral oil, no luck.

I can mail the noise.wav file to interested peoples, couldnt attach it to this message.

The comment I got from BMW is that it could be a bad valve lifter or "stucked VANOS"... Wht do u think?

[themadhatter]

I have to agree with the bad lifter theory. the euro M3 motor needs regular valve and lifter maintanance and this is one of the drawbacks of it.

when was the last time you had the motor serviced?

-Ron

[modic]

Had an oil service 5 000km ago and a service 1, about 20 000km ago. That one included controll of valve play etc. I do all service and repair myself so I checked the cam lobes and valve discs (shims), looked like new, no scratches almost no carbon deposits.

Could it be related to the build up of the oil pressure? Or the building up of oil pressure in the VANOS reservoar (the can with the steel pipe connected to VANOS unit).

[Sinned]

these things can be attributed to simple electricals in the engine...such as spark plugs, oxygen sensors on its way out...you might want to try the plugs, because my car idled way better after new plugs...but if that doesnt solve it, its usually time to adjust the valve train timing...

[modic]

Thank You Sinned. But, I have not found any failure codes and no "burning" problems on the sparks. Have a powerfull diagnose tool for the ignition system as well. Think it is related to a mechanical problem as it comes and goes away in a very systematical way after a cold start.