Originally Posted by archrival
Check your fan clutch and also all your pulleys on the engine
98 M44's do not have a fan clutch, their all electric fans only.
I'm thinking it's just your belts slipping on start up, to test this, next startup when it's making this noise get some belt dressing and spray the belt and see if it goes away. If so a new belt is all you need and possibly a a belt tensioner.
If no difference +1 on archrival"s advice for finding a worn bearing.
"They say ignorance is bliss..... I don't know what the Fu*k that means but I'm pretty happy". Ricky Trailer Park Boys.
Current Mods....X-Brace, Stromung Cat Back Exhaust, 17/225/45 M3 Replicas, HotBits Adjustable Coil Overs, 40% LSD 3:91 Diff, E30 Gearbox, Boosted.