I've had EVERY problem that one can have with overheating...

There are two W124s in my garage, both are currently normal.

#1. Make sure you "burp" your cooling system. Disconnect your upper radiator hose and fill it wth distilled water, preferably while on an incline.

#2. Make sure your cooling fans are plugged in properly. My 91 300TE was wired backwards...it can happen!

#3. Thermostat...change it. Always have three floating around and anyone can fail and still look like its perfect.

#4. Water pump...yep...had one fail.

#5. Fan clutch.

#6. Do all the easy ones first...its probably one of those. Good Luck!

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I have never met a man so ignorant that I couldn't learn something from him. -Galileo Galilei, physicist and astronomer (1564-1642)