I have a 1998 E320. The water temperature doesn't seem to get above 80 degres C even though the outdoor temperature is about 40 degrees F. What is the factory specified normal operating temperature for the V-6 engine? At what termperature does the thermostat open? How does one replace the thermostat if it is defective as a DIY project? Thanks, Tom

 

80 degrees C is normal operating temp. Do the conversion to F and you wil;l see that its much higher.

 

I need to change my thermostat too. Its on a 1997 E320 with the 104.995 engine (straight six). The change looks fairly straight forward on my engine, just unbolt the cover and change. However, I have a question for those of you that have done this; can this be done without draining the radiator?

 

It is easy to do it yourself with an Inline Six, i would recommend to drain the coolant, if you haven't had a flush. So you can start a fresh one.

 

I drained the radiator (which drained the resevoir) and replaced this coolant less than one year ago. I did not have a way to drain from engine as it did not have a block plug. Is there any way to flush engine block as a DIY? And as I originally asked, can the thermostat be changed wihtout draining. It seems that it may be high enough but wanted to ask first.

 

Since you said you had your coolant change, then you don't need to drain it to change your thermostat, but you have to keep in mind there's gonna be coolant under the thermostat.