Folks i need some advise, i have a 1990 300E 2.5 turbo, I just purchased knowing the diesel knock was not much to worry about. I had read all the posts ref this concern & as the car has 165000 i thought new injector nozzles "Bosio" would cure the problem.
Replaced them yesterday, engine was much smother but still has the nasty diesel knock just a little more uniform now. there is no smoke and car has all the power, turbo works fine, no blow from the valve cover. it also seems the # 5 cylinder is not running as strong as the others, " i crack the fuel line with not much change in sound or rpm".
this is my first diesel Mercedes, i am a competent master tech but have not much experience with diesels.
I had a thought & wondered if maybe the hyd valve lifters may have collapsed, the engine runs very smooth when cold " all cylinders seem equal " the running deteriorates on # 5 when correct eng temp is reached. diesel knock is always there until engine is brought of idle, also # 5 cyl is ok after approx 1700rpm.

all problems are at idle only, i was very surprised at the great performance from a 2.5 diesel, i get approx 40mpg with ac on.

any help would be much appreciated.

thanks very much.