Heating Problem

[AMB]

hey i got a 1991 240 and i have changed the thermostat twice already but it will still heat up untill its right under the red mark on the temp gauge it will not over heat but it is running very hot anybody have a solution.

[Three Fat Tigers]

Are you sure it is really running hot though? If that reading is correct and it's that hot, when you open the hood you will know it, it will be insane in there and the cooling fan roar should be consistently present.

Assuming it is not running hot:

→Test the gauge:

buy an potentiometer, for example: http://www.amazon.com/Parts-Express-500-Ohm-Potentiometer/dp/B0002KRE16

Connect this in between the sensor wire at the cylinder head and ground, set it to 75 ohms, the gauge should read right about the 3/4 position.

↑If that looks good: try another temp sensor;

↑If not: bypass the compensation board: http://forums.turbobricks.com/showthread.php?t=105959

and or replace the gauge.

Assuming it is running hot:

→Check the cooling fan:

Should turn stiffly by hand when the engine is freaking hot, and you should hear fan roar when engine is revved. Compare this when the engine is stone cold. If it's about the same, you need a new fan clutch; when replacing don't be tempted to buy an tropical clutch unless you really like the sound of fan roar.

→Take the fan shroud loose and back flush the external radiator fins with a garden hose to remove any trapped dirt.

→Try another radiator or have the current one flow tested.

→Make sure you are installing the thermostat correctly with the little hole pointing up.

[AMB]

thanks man yesterday i drove the car with the thermostat out to see what would happen and it was the same thing so im thinking its the gauge like you said or the sending unit thanks alot i will check every thing u said

[AMB]

what is the normal operating temp for the 240