To all of you good people that have tried to help,with the start up noise on my 1980 450sl.As you may remember.Light knocking sound.only when car moving.In three to five minutes knoise would go away.Well a new development.This may give some of you enough info to pin point the problem.Yesterday.and today when I started the car and drove off NO NOISE.The only thing diffrent was that it was warmer.I know that the car has a cold start system among its many parts are an extra injector tha sprays extra fuel when it is cold.I am wondering if something could be messing up in that system,causing a lean run condition when cold and causing the knock.What do yall think.Thanks Michael

I don't see any form of mixture problem causing "knocking" noises. Misfires maybe.. misfire based rattles yes. Does it misfire?

How bout a loose catalytic convertor. Try banging on it with a rubber hammer with the car on a lift.

I base the thought on the difference between hot, cold. The catalyst takes longer to cool as it is well insulated.

update shesa maka noise.
 

Thanks steve for the reply.No There are no misfires.The car has been totally consistentin this light knocking.Every time when i first start it in the day.If I let it warm up a little no noise The last two days have been the only times It would not knock.The only diffrence is that it was warmer.again thanks for the reply

Have you checked the oil weight? If you run heavy oil in the winter it may take longer to fill the timing chain tensioner or hydraulic valve compensators. Rocker could be tapping. Possible??

Steve
’85 500SL (Euro)

Knockin
 

Sounds like your not having any problems other than a knocking sound. This could be coming from your Enviromental Air System. (Heater & AC). MB's have a tendancy to create a knock when they are too hot or too cold and it sounds like its coming from the engine but actually its coming from under your dash near the Floor board.