Engine overheated and shut off
 

I started the X up this morning like i do every morning and let it idle to warm up. when i came out about 10 mins later it was off with all the coolant on the ground and it was not running. Opened the hood and the top of the coolant tank had blown apart. I put a hose in the bottom part of the tank and started it to try and get it to cool down. Engine was making a lot of noise for the first 20 sec. sounded like detonation till the engine started cooling down. It starts up fine and sounds like it always does but my temp gauge is pegged on hot after it has sat all day. Im going to order a new tank, water pump and thermostat. When I had it started there was no smoke or steam coming out the exhaust and the oil was not milky. I just can't believe the amount of problems i'm having with this truck! Its an 04 with less then 40,000 on it,it should not have the list of repairs i have. Any one know why the temp gauge would be pegged on hot after it has sat all day and is there anything else I should check?
Any help would be great. Thanks, Ron

My guess is the coolant temperature sensor is F#%*ED. New one is $20

^ a coolant temp gauge? I'm saying you have at least a full cooling system replacement. If the expansion tank has failed then all the rest of the cooling system is not far behind. I hope that you did not overheat the motor until failure. Have a professional assess what has happened and move on from there. Good luck.

also consider that the coolant system needs to be pressurized. if not, it won't operate correctly.

Really 40k miles? Did you buy it new?

Dinan, what do you mean by the system needs to be pressurized to work? Do you mean, as in no leaks, or is there something special you have to do to these cars? I am guessing just no leaks, and it will pressurize by itself.

Slick, just meant that the cooling systems on these cars are designed to operate at around 15psi. Not sure if that affects the OP's issue.

I agree with this. It's not so much the miles but the age. I had my coolant expansion tank go bad recently(05 4.4i with 70k miles). The black plastic parts in the engine gets brittle and hoses dry out after time. My mechanic examined the car and noticed my upper coolant hose was looking bad. This prompted me to replace,

expansion tank
upper and lower coolant hose
thermostat
radiator
water pump

You should also check your belts and other rubber hoses in the vicinity. My power steering hoses were also going bad so I had to change those also. At the very least I would change the tank, hoses, and thermostat. I got them from AutohausAZ and it was very reasonable.

Thanks guys i'm going to start going through everything this weekend. Going to start with video scoping the cylinders to see if theres any scoring. If that checks out i'll change out the temp sensor,water pump, thermostat, coolant tank and anything else that needs it.
Slick, I bought it used in 06 with just over 12k on it it has 38,757 on it now. Here's what i can remember of what has gone wrong. front CV boots, the whole air ride system witch the dealer had for almost 2 months the first time a few window regulators, brakes, nav screen,sunroof track and motor,the coolant tube that runs from the front to the back of the engine block, that was a lot of fun! front air springs and compressor witch i just replaced again but this time with Arnott parts and i was just about to replace the transmission mechatronics module because it hangs up sometimes shifting from 3rd to 4th and when going along at like 45 it feels like the brakes are being tapped every 10 sec. and im sure theres a handful of little shit i missed. Is it me or does that seem like a lot in 25k?

RC, you're right on the money with your analysis and parts replacement. It appears that all the specific 4.8is problems have been addressed already and this current problem is just a time/mileage issue. Good luck and let us know how it turns out.

Yea man in 25k miles that seems like a ton of shit. Don't feel bad. I am the third owner, and I got all the service records from my 4.8is. The two owners that had it before, were at the dealer every month getting some random shit replaced, or diagnosed, or some rattle complaint. I would kill myself if I had to go to the dealer once a month. I am just praying that all the BS got replaced and upgraded with the previous two owners, but alas, I too have developed a leak somewhere. Don't know which fluid yet, but looks greasy. I'll start a thread soon after some more investigation.

Good luck with replacing stuff. Look on the positive side, once you get this taken care of, you will be good again for a while.

seen this before, a dealer i knew used to go start each car and leave it idling until one blew the motor.

man i know you must be suffering but i have to ask why would you do that, leave the car unattended idling??

its not like your in a cold climate are you??

i think your hand book tells you to not do that, but to get in and start driving from the get go. just take it easy till it warms up,

bit late now i know, but once you get it sorted i wouldnt be doing that again

Slick, All I know is when im done fixing this i still have the transmission to get to! one good thing I did was set up a wholesale account at my BMW dealer today. Spent 96 bucks on a coolant tank and temp sensor that should have been around 160. BigWave, Most of the time it warms up for 5 mins and im driving. Monday i got sidetracked for 15 mins. I think my coolant tank just failed and boiled the coolant out. I had to replace the tank in my M3 a few months back because one of the little vent hose barbs broke off when i touched it changing the oil. i've read alot about these tanks failing. Im hoping thats what caused this. Started working on it tonight scoped 2 cylinders and they look good ill do the rest tomorrow. drained the oil, no water in it. Also pulled the temp sensor and thermostat for now. One good thing is it started right up and ran smooooth for the minute it took to get it on the trailer and off when i got to my shop. keeping my fingers crossed that everything goes good tomorrow. Ill let you know. Thanks again for the input guys.

Well I finished scoping the rest of the cylinders and they all looked fine. Did a compression check on all cylinders and they where all around 180 PSI accepte # 5 it was at 155 PSI. Changed the 2 temp sensors, pump, tank, thermostat, oil, filter and spark plugs to E3s. Started it up and ran it for about 45 mins checking the temp with my IR temp gun. It never got above 165 but the temp gauge in the dash is still all the way on hot. When I turn the key the gauge moves to cold and as soon as the engine starts it goes right over to hot. Not sure what else to look at. Any ideas? Everything is working the fan comes on it runs fine and it's not making any funny noises. I tried disconnecting the battery for about 10 mins but the temp gauge is still not working right. Going to take it to get it scanned and hope that tells me what I need to know about the temp gauge.

Hmmm, if you changed the temp sensor and you're still getting a false reading then I would think its either the gauge itself or something in the wiring is off.

Did you try and see what the temp gauge will do with it disconnected from the sensor? You would think it would not move at all but if it has the same behavior then that should confirm its not the sensor.

Assuming nothing wrong with the gauge or sensor, I'm thinking maybe its not grounded properly or something in the wiring is shorting/loose.

I did check it with the sensor unplugged and it did the same thing. in the big red book it shows the sensor, a/c, fan, temp gauge and other things plugged into an ECM. I'm thinking ether the ECM needs to be reset using a scan tool or the ECM or gauge is bad.