We recently bought a 1987 300e, no records, showing 133k. I noticed that the overflow tank does not fill up as the car heats up, and there is no pressure in it when the car is hot. Additionally, the hose to the pump below the tank jerks approximately once each four seconds. Finally, the radiator top is hot on the drivers side but virtually cool on the passenger side. Coolant is green. Any thoughts? Thanks, Bob.

I would start with the basics. Flush out the green coolant and replace the thermostat. When refilling the coolant, use the MBZ coolant or MBZ approved coolant. You may have an air bubble in the system since it is low. Do you have any other problems cuurently with the car, (smoke, hard starts, no heat, sweet burning smell, high temperature or very low temperature etc..)?

Your radiator is not circulating properly. Get this checked ASAP. Do as advised above. What is your temp gauge telling you. It otta be on the high side. If so, don't wait, you are flirting with a blown head gasket.

Be sure to install a new factory Radiator tank cap first@!

I have seen hundreds fail. The small check valve will fail and allow the system to vent instead of building pressure.