Help!!! M3 Overheating issues!

[Urinal Cake]

First off, let me begin, I own a 1998 M3 with light mods. I have owned it since August and I must say that I am in love with it. That said, I am beginning to have the first "major" mechanical issues with the car since I bought it.

Yesterday, I let a buddy drive it while I was at work so he could begin my suspension install. He claims he was driving it on the interstate and he admitted that he was performing some spirited driving, and a radiator/coolant hose blew off and leaked coolant everywhere. It began to creep up past the halfway mark on the Thermostat gauge until it got near red, but never near red and they drove it home. The hose that blew off was the one near the intake that connects to the radiator. When this blew off, a circular metal/radiator piece blew off and broke as well. We were able to reattach the hose and tested no leaks. We filled it back up with coolant and water and I drove it around a little bit that evening and the temp gauge only got to halfway, where it normally sits.

Today, I get in the car to drive about 5 miles to return the spring compressor that I borrowed for my suspension install. About 4 miles into the trip I can see the temp gauge getting over the halfway point and towards the red. It stayed roughly around the 3/4 temp gauge. I got it to the store, and took the radiator cap off and of course it was bubbling and then the engine said "check coolant level, see owner's manual". We put a mix of water and coolant back in the car, attempted to drive it home, but it was still hot. It would hover around 3/4 hot and got close to the red. Never did it get it the red, as I played it safe getting it home by coasting where I could. One odd thing on the trip home, when I went around a corner, the temp gauge went down to halfway, then as I straightened out, it began to creep hotter and hotter again. I have it home now, and I guess my question is, where do I begin to diagnose this problem. I don't believe there are any leaks (from what I can tell). What is it that's causing this overheating problem, where should I begin. My car has never given me any trouble until the radiator hose blew off and ever since it's just not staying at the right temperature. Any help, insight, or advice anyone can provide would be greatly appreciated.

Thanks in advance.

[Bud Brown]

usually once your needle starts going north of the middle mark its too late.

:(

[Urinal Cake]

usually once your needle starts going north of the middle mark its too late.

:(

Too late for what?

[RAT3D M]

was there air in the system maybe causing an air bubble ?

[Racer01]

Something is not right. The hose should not pop off (even at the track) even if the car is driven hard. I would be looking for air in ths systerm (#1) and then possibly a thermostat (what caused the hose to pop off first?) and then headgasket (result of your friend overheating it).

[crotter]

:nono never drive the car with the needle anywhere other than straight up!

remember, in these cars the temp gauge is simply an "idiot" gauge... meaning that it will only move to the right once a certain temperature limit is exceeded. Thats why as soon as you see the temp gauge creep over, you should immediately shut it down and figure out whats wrong. Under normal operating conditions the needle should never move from the 12 o clock position...
hopefully serious damage hasnt been already done...:eek:

[Urinal Cake]

Now, we bled the entire coolant system, and filled up with new. My friend did suspect that there was air in the line. Ever since then, no overheating issues. I will drive it around, because we only tested by revving to about 3K and letting it idle, and it stayed rock solid at the 12 o'clock position where it already has. What do I need to check out to insure that no further damage has been done.

[RAT3D M]

before you drive around ,turn the car on turn the heat on hot and turn it on high ,let the car sit and watch the needle ....... also let the car run for a while and unscrew the filler screw and see if any air comes out ,if so wait till you start to see bubbles and then a steady stream of coolent then close it ....at this point all the air should be out the system ..

[Urinal Cake]

before you drive around ,turn the car on turn the heat on hot and turn it on high ,let the car sit and watch the needle ....... also let the car run for a while and unscrew the filler screw and see if any air comes out ,if so wait till you start to see bubbles and then a steady stream of coolent then close it ....at this point all the air should be out the system ..

Kudos. I believe you were the one with the correct prognosis. We unscrewed the filler screw and you could hear all the air come out. We then filled it back up with coolant, drove it around for a solid 20 min experimenting with various RPMS and the needle on the temp gauge stood pat at the 12:00 o clock position. I will keep a keen eye on the temp gauge for the next few weeks, but I believe the problem is resolved.

To all those that say "I hope nothing else major happened" because of this incident of me driving the car for a short duration while the temp gauge was past the halfway mark, I ask, what could I be looking for to reflect more damage? What else could I have done? I've already checked the oil and there are no signs of coolant in the oil. I also have verified that no leaks are present as well. Any input is greatly appreciated.

[beatniks325]

what hose came off? you didn't snap your radiator neck did you?

[L3000C]

overheating in any car is horrible, your headgasket will pay the price in the long run, and will fail when u least expect it.....

[okiem5]

Make sure u only use the blue BMW coolant. If u use that green stuff it will corrode your engine inside out. Also, only use distilled water or deposits will accumulate inside your engine.