Overheating Issues

[zlatan]

2007 MS3 57K miles ( Do I still have warranty?)

My car has been experiencing intermittent overheating issues. I've spiked as high as 237 before and shut the car off and let it cool down. Cruising around my temps are normal. However, @ random times I get heat spikes and I overheat or hit temps I don't want to see (220's) I also am having heater issues where the car blows hot air at idle and stops @ times. This happens as randomly as the overheating does. I have no signs of a blown headgasket. No oil in coolant/coolant in oil. The car still pulls like a champ. However, I've reached a point of frustration where I don't know what else to try and swap out to fix it.

I've swapped/tried the following:

Thermostat (tried a used one and had the same issue now I'm on a brand new OEM)
Water pump
Coolant box and cap
Checked lines for leaks (none found)
Burped the system


I'm just tired of having to monitor temps all the time on AP. I have no idea what else to check. I've heard that the ECT sensor could be a possibility as well.

Your thoughts?

[zenger]

flush it out

[zlatan]

Originally Posted by zenger flush it out

did that

[driver311]

I think its the cap. When we crack the cap the thermostat opens and it cools right off. Its got suction in the system that doesnt allow the thermostat to open. But its intermittent. itll work for two days with 0 issues then out of no where its a pain again and overheats. I tried everything I knew.

therostat
water pump
flush
but it got bad when we replaced cap and overflow. Its like it cant breath and builds up pressure????

[zenger]

Sorry burp the system must be flush? Lol

Sent from my Galaxy Nexus using Tapatalk

[MS3-a(sore)ASS-rex]

Could be a pinhole in the radiator

[driver311]

Somethings creating suction keepin the thermostat from opening consistantly. its very weird. Its like the system cant breath

[MS3-a(sore)ASS-rex]

Pinhole in the rad would mean no leaks (fluid wise) and that air is being pulled into the system at a very slow rate. Which would explain why the overheating issue would only come back every couple of days instead of immediately.

I know you recently worked on his car, did you guys bang it or hit it with any tools by chance?

[driver311]

I have an idea. thanks for the suggestion.

[easy]

i was going through a similar situation. I tired burping, changing cap, and tstat but it kept over pressuring and spilling out of the bottom of the res. The service manual said to bleed with the cap on the res. Not sure how it works, but i guess it does. Im assuming with the cap off when trying to burp will pull in air when the tstat opens. Manual says to get car to op temp and hold the rev to 2500 for 2 or 3 mins ... do it twice and on the 3rd time rev to 3000 and hold for 5 secs. Let the car completely cool till the needle is at the C and then you can open the cap to fill if needed. This worked for me .. but i ended up replacing the res because i think i had a hair line crack somewhere.

[qtrmile beast]

So are any of you guys pushing coolant out of the overflow while boosting because it is over filling and pushing past the cap?




Also is your fan coming on? Here is a test there is a wire harness on the passengerside of the radiator with a single red wire (speed6 not sure about the speed3) just unplug it while the car is running and this will cause the fan to run all the time. If your car doesn't over heat like it has been then your fan module might be bad..

[zlatan]

Will be replacing some hoses tonight and burping the system. I will update the thread after with results.

[zlatan]

Changed out the two bottom hoses going into the other side of the block and refilled with coolant. The hoses had bulges on the edges and seemed weak and swollen. Did some WOT pulls and never hit over 199. Did some cruising around down and saw high 180's low 190's. Got home after doing some pulls and idled at 210 after sitting 5 min. Drove on it and immediately had temps go back down. Checked the bottle and noticed it was empty. I topped it off now.

Cliff note?

I think it's fixed!

[driver311]

I think the system just had some very small air leaks and needed to be bled. Im gonna try the burp deal again and check the fan. . Thanks guys for the help. Mine never gave me any grief like this. LOL