1990 500sl overheating
 

this is my first post on this forum. I was told to come here because it was full of "wrench monkeys." Anyway, i got this car from a good friend who bought it, intending to restore it, but now i have it. By the way, im only 16 years old and im pretty mechanically inclined. So, im trying to do as much work myself so that i can save some money. the engine overheats after about 10 minutes, even when sitting at idle. we replaced the thermostat and i had the radiator checked and it was A-Okay. :) However, the previous owner replaced the mechanical fan assembly with an electric type, which really sucks. also, when they did this , the removed the fan shroud. so, now the fan is only drawing iar though a spot about half the size of the radiator. my question is; would this be enough to cause such severe overheating? Or does the fan only turn on when the engine starts to overheat? Lastly, does anyone have a manual or know where i can get one for reletively cheap/ preferrably free, like off the internet;) thanks and sorry my post was so long.

Definately. You need to find out why the fan was changed (probably a clutch failure and this was a 'cheap' fix), and how the thermostat is connected. The fan turns on at a preset coolant temperature.

Manuals are available, CD versions are cheap. Parts aren't though, but I'm sure you'll be way ahead to find the correct fan and return the cooling system to how was originally designed to work.

ALL cooling fans need a shroud to restrict air flow to pass through the radiator fins/tubes. An unshrouded fan is simply beating the air around it, probably less than half is getting drawn through the radiator. The fan should be as big as possible.