Engine Ticking noise

Hi folks.
Recently, i have noticed at ticking noise from my 300tdi engine with 121,000 miles at higher revs that doesnt seem to occur so much when the engine is cold. The engine has just been serviced with oil and filters. Its not very loud but as the revs increase the noise is more noticable. I cant hear it when the engine is ticking over so i am struggling to diagnose the problem. One other thing i have noticed (not sure if related) is after i warmed the engine up and then opened the oil filler cap i noticed small amounts of oil spitting out... is this a sign of engine wear, i didnt noticed it before (but the engine was cold).

and one last thing... ive noticed that the brake pedal makes a hissing noise when depressed when the engine is running during a run out. Is this normal???

thanks alot.. Josh

sounds like your brake vacuum pump is starting to fail - plunger within runs against cam lobe and can wear creating a hollow and as this rotates so can find a new area to run on so creating a tapping noise. Your brake hiss can be the small rubber "o" ring behind master cylinder to servo joint.

I concur with bmp42.

Thanks for your help. How soon should i change the vacuum pump if its ticking like it is? As i plan to do over 100 miles on saturday and dont think i will get the time to replace it.. Is this not wise?