The other day my 300m overheated very quickly and puked coolant and steam every where. So far I have checked the fans, hoses, and individual cylinder compression. All of those are good, and there is no noticable loss of coolant under the car. After tons of bleading of the system the heat started to work again. Tomorrow I will take the thermostat and water pump out. I will probably replace both either way.

Is there anything I am missing?

 

Did the fans stay on all the time when you were driving? And did they ever turn off?

 

The fans cycled on and off a few times in the ~20 minutes of idle I tested with. I even held the throttle at 2k rpm for ~3 minutes. I could not get it to overheat again.

Right now it is in the air. I went for removing the thermostat, but once again the cramped quarters ran me off. Is it worth the extra room to remove the alternator and oil filter? I need an oil change anyway I guess. What sizesocket is used to adjust the alternator belt tensioner?

Thanks for the help!

 

i would look into the radiator being blocked before taking out the stat.the location sucks,if its only while your driving.in all the years of working on these 300's ive only repplaced 2 stats and one was because i was rebulding the engine.moe

 

Part of the process of getting the thermostat out involves draining the cooling system. I plan to do a flush at the time. I am able to get good flow from the bleader valve, so I don't think the system is blocked. I will know more when I do the flush. This beast is just shy of 200k miles! I don't mind throwing in an $11 part just to be sure I don't have to do this again. After the thermostat I plan to get the water pump off and check it. What is the expected life of the water pump on these cars?

 

I have removed the top and bottom mounting bolt for the alternator. Are there any other mounting bolts? Do you have to remove the bolt holding the electrical wires to the back of the same hole as the top alternator mounting bolt? How do you get the top alternator mounting bolt out of the hole? Its brake time, but I am set on getting this alternator out today.

 

I finally broke down and removed the upper radiator support. It was much easier to do than I thought, and it gave me tons of room to work. Tomorrow I will buy more coolant and test the system out. I also plan to check the torque on the tie rod I installed last week.

 

How much would a cooling system flush, thermostat & gasket replacement, and oil & filter change cost at the dealer? I just totaled out at $95, with extra coolant.