Hi I have a 1987 300d 220000 KM, when I first bought it it ran fine but slowly over the past 4 months or so I noticed this problem getting worse, what happens is when i start it cold it blows a lot of blue smoke and runs rough, it was not noticable at first but it has gotten worse and worse more smoke than usual and now very rough, I hold my foot on the gas now and give it some gas so it dosent run so bad while it is warming up, as soon as it warms up it runs fine and does not smoke.this does not just happen during the 1st and 2nd glow cycle but continues untill it warms up to about 60-80 deg........what I have done so far is tested the glow plugs, they are all getting power but are verry black...compresion test was good, new fuel filters, pulled and cleaned the injectors, new fuel primer pump and new air filter,and it does not burn much oil at all when driving..... what could be causing this problem? the fact that this has been happening slowly and getting worse should be a clue right? I do have some little vaccume leaks could this be it? any sugestions????

 

Quite likely it's oil seepage past the valve stem seals.