Ok so I have had this car for about a year and a half, I'm trying to work with it and I love it to death but i'm really just learning. So to the problem at hand, when I start the car it runs fine, except it takes a little longer to shift then it used to, there aren't any irregular noises coming from it but after about 5 minutes it slowly creeps from its usual 86 degrees to more then 120. So I can only drive it for about 12 miles maybe more before it over heats and shuts off, then I have to wait for it to cool off before I can drive it again. Now the weird thing is it doesn't heat up at all when its idle. I flushed the radiator and check the fans but im not really sure what else to do, can anyone help me?

Well it has to be eliminated so change the thermostat. It may not be the problem but youi have to know. Also you could check for bubbling in the coolant first.

Do you shut it off, or does it shut it's self off? These cars do not have an auto-shut down feature if they over heat...if it shuts off it is seizing up!

__________________
1979 240D- 316K miles - VGT Turbo, Intercooler, Stick Shift, Many Other Mods - Daily Driver

1982 300SD - 232K miles - Wife's Daily Driver

1986 560SL - Wife's red speed machine

__________________
Jim

Welcome to the forum.

The thermostat is the first course of action. If it's stuck closed, the symptoms will be identical to those stated.

The other possibility is a decomposed water pump.........happens on occasion but it's relatively rare.

Please also state the ambient temperature when this issue occurs.

Also, please provide a history of the problem. Did it suddenly occur........or did it gradually occur.........starting at 90° and slowly creeping up toward 120°C. BTW, running the engine at close to 120° C. and then waiting for it to shut itself off is a recipe for a cracked head..........don't do it. If the temperature reaches 110°C. and you are not on a very long climb on a hot day........pull the vehicle to the side of the road and call a wrecker.

I would love to check if the thermostat is shut closed or not but I don't know how. I really am new with this sort of car.
As for the history, about a month ago the car started to take a lil bit longer to shift and I had to put a lil more gas to get it to shift to the next gear, before it died it took like 3 to 4 minutes just to get to 30 and I would have to push the gas almost to the floor and this is in about a month time span.