i recently bought a 1989 530 from down south drove it back home approx
200 miles , 3/4 the way back started to overheat , stopped car and
checked water which was obviously low , a new radiator had been fitted
very recently so we thought that perhaps it had air in system and
was`nt bled properly , so off we set got home with no further
problems , on driving the car around locally the next week ,
discovered that temp gauge was`nt heating up just going onto the end
of the cold blue marker , i then decided to take the thermostat
housing off and replace the thermostat , again thinking that it was
probably stuck open , you no what im going to say next there wasn't
one fitted , so i replaced it and bled the system , took it for a run
and then it was overheating again , ive read an article which tells
you to bled them over and over and over which i have now done , the
car now still only registers on the end of the blue marker , but if i
get in traffic it will go up to the half way mark which ive always
thought on any car is correct , my problem is its still running
lumpy , on checking the spark plugs ive discovered that out of the six
plugs , 5 are what i would call perfect colouring with one , number 1
plug is black not oiled black but sooty black , can anyone shed any
light on what they think might be the problem , another thing ive
forgot to mention is at slow speed car does`nt seem to want to pick up
ie when you put you're foot down on accelerator peddle it hesitates ,
once you get it up to 60 or 70 shes fine  , cheers wayne.