2007 M45 Overheating

[M45brasfield]

All, I have a 07 M45 that overheated Friday night. The return hose disconnected from the radiator. I reconnected the hose, refilled the coolant, bled the system and replaced the upper thermostat. It is still overheating and a Service Engine Soon alarm is on. Any ideas??

[Ilya]

Do you have a way of checking the cause of the light? Do you have a scanner?

[EdBwoy]

All, I have a 07 M45 that overheated Friday night. The return hose disconnected from the radiator. I reconnected the hose, refilled the coolant, bled the system and replaced the upper thermostat. It is still overheating and a Service Engine Soon alarm is on. Any ideas??

I have seen the SES light come on for overheating. The code was something like "engine over temperature", followed by a decrease in performance.
Does your car overheat almost immediately after warmup, or only in slow traffic?
Do the fans run?
Radiator clear of obstructions?

You didn't mention how long the engine ran while overheated, but you might still be getting the overheating indication because aluminum engines like ours don't handle overheating very well. Over a certain temp + duration a gasket leaks or engine component cracks and that's that.
To narrow down if a seal is compromised, are you seeing any of these symptoms?
1. White, sweet smelling smoke from the tailpipe
2. The engine oil looking milky
3. Coolant has an oily sheen
4. Too high or too low coolant level in the resevoir
5. Bubbling in the reservoir
6. The heater in your car doesn't seem to get warm unless you're in motion

And another maybe unrelated point - the return hose is the lower one/ driver side. These have pretty beefy clamps on and you'd need a good amount of pressure/obstruction to pop it off. Any idea what happened there?

[Sstupid]

If you didn't blow a head gasket or warp a head during the initial overheating, I'd say you might just have air in the system. It's hard to get air out, sometimes.

Edit: Ya know, I was considering why the hose popped off in the first place. I bet it was the system over-pressurizing. Your thermostat or water control valve might be stuck closed. Change the thermostat and try again. If that doesn't work, try the water control valve. There's a thread on the first page titled, "2 thermostats" that you can read for reference, from "ken in az."

[Larz]

You may also want to make sure that there are no air pockets getting stuck by the thermostat. After I had my maintenance flush done (at the dealer), about a mile later, the temp gauge shot up, the air/con shut off, and the CEL came on. The dealer re-did the flush, burped the system, and all has been fine since then.

[Kadrian21]

Mine did the exact same thing I first replaced the thermostat didn't work so I took it to a shop and it was the radiator I also had the fan shroud replaced total was a little under $700 here in Texas