213 K miles on MB 300TD. Have owned since Dec. Replaced Valve seals, Alternator, Belts, and AC compressor.

Now having first warm weekend and have temp gage rising at idle to over 100C I am sure this has been asked before in this forum.

Pertinent background looks like a DIY shade tree mechanic with channel locks replaced the water pump. They barked up fan bolts so bad can’t get socket on them. Car does not consume oil. So not sure if the past presumed overheating problem lead to ring damage...Also appears to be loosing coolant but without obvious leaks.


Let's check the possibilities

Thermostat,
Clutch on fan
Head gaskets, booo

Please let me know if for instance there is some thermostat, solenoid or bypass valve or some such that I am not aware of.

Also help me set the priority on the first likely /least costly paradigm that I should try on this problem.


Thanks

Stephen Porter








but histor

Hey Stephen,
How much coolant is your car using? There is a possibility that the previous owner overheated the engine and caused major damage, but let's not focus on that yet.
First I would check the cooing system to ensure that there is no air trapped in the system. Do this by removing the temp sensor on top of the t-stat housing, cold eng, res cap removed. If no air is trapped in the system coolant will be immediately present.
Next I would test the t-stat. It may be partially stuck closed.

Replace the Thermostat
 

Greetings,


Almost all overheating problems, or excessive heat in cooling system ends up referring to a few basic parts. The first and cheapest is the thermostat. Just change it, and if the bolts are as bad as you say, file down the sides until the next smaller size socket will fit, then replace them with the thermostat. If you water pump is failing you will see antifreeze seeping from the weep hole on top of it's housing, that's why they drilled the hole there for, to tell you your pump seals are toast. The last item would be a head gasket leak which would show mostly white smoke during operation at idle, regardless of engine being warm or cold, more pronounced before operating temps, because coolant is trapped in the block until the thermostat opens.
My best guess is that the thermostat is not OEM and has failed. Order the thermostat off Fastlane before you start your dissassembly, so you can go ahead and change it out.


Charles

Water Temp
 

Charles Will try the thermostat route first thanks

Stephen

Check the electric aux. fan first.
Could be a simple as a fuse.

A lot of cooling problems especially on older cars is a plugged radiator either inside or out or both. When you have the coolant drained it would be worth while to pull the radiator out and have a look.