Car overheating - United Bimmer Community

DEATH2000 · 06-25-2006, 01:05 PM

Well this is retarded. For the first time since ive owned the car its starting to overheat. I dunno whats wrong, but the other day one of the top rad hoses poped off. so i stop the car wait for it to cool off then re attach the hose,drive the 1km to my house in which the temp is fine and all even though im running low coolant. Then when i top it up it starts to overeat. So im like ok, let it cool off and what not, then when i take off the cap a bunch spews out so im like ok w/e. Wait a little till the car is kool, top off the coolant again then it overheats again. I think its the thermostat thats busted but im not sure. Any ideas?

witeshark · 06-25-2006, 01:26 PM

Yeah the thermostat may be clogged and it seems there could be a leak somewhere

**Dudesky** · 06-25-2006, 05:53 PM

I waited a few hours to jump in here . . always feel like a dick for trying to answer everyone's technical q's

Anyhoo, once the car has reached normal operating temperature, you should feel pressure and flow in the top radiator hose; that'll tell you if the thermostat is working. If you can easily squeeze it, then your t-stat could be stuck. But my guess is that you have air in the system, just gotta bleed it . . it's the usual culprit for weirdness like that.

DEATH2000 · 06-25-2006, 06:03 PM

Quote:

Originally Posted by Dudesky

But my guess is that you have air in the system, just gotta bleed it . . it's the usual culprit for weirdness like that.

Well see the top rad hose did pop off so that could be the problem. Only thing is i dunno how to bleed it. Would a coolant flush work too?

**Dudesky** · 06-25-2006, 09:26 PM

http://www.pelicanparts.com/BMW/tech...lant-Flush.htm

**Spieluhr** · 06-26-2006, 02:56 AM

also are you adding just coolant? because our cars require a mix of coolant and water (distilled i believe), and a mix of 50/50.

but yeah, check to make sure your t-stat isnt stuck.

**c1apton** · 06-26-2006, 07:33 AM

Hey "D", what's your definition of a "little while"? The average BMW takes hours to cool off enough to open the radiator cap. I tend to think Dudesky has it right - you need to bleed the system and that should solve your problem.

DEATH2000 · 06-26-2006, 01:54 PM

Speiluhr i add a mix off coolant and water. C1apton, i think since the temp cauges climbed so high so fast and then within 20 mins allowed me to open the rad cap that it might have beeen the thermostat. But ill replace the thermostat and bleed the system just incase.

**bitcore** · 06-26-2006, 05:49 PM

you need to bleed your system.
when you overheat and a lot of the coolant boils off (it expands and overflows out of the pressure cap) and is replaced with air. When you top off, the reservoir is full, but there is still air in the engine\top of the radiator.
Open the bleeder valve and let it bleed out, it may take a while. Pelican parts article describes how to do this.

There is also a reason that this happened in the first place.
1. Hose wasn't clamped tight enough (whoever may have worked on it could have tried to avoid crushing the radiator hose neck since they are fragile and force you to replace the entire radiator) -tighten but BE CAREFUL because you can destroy your radiator by turning that screw too much!
2. Thermostat stuck closed and pressure built up, blowing the hose open. - replace
3. Your pressure release cap (the radiator fill cap) is bad and is holding more pressure than it is suppose to - replace
4. Your car got mad and you are now in for one hell of a coolant part replacing binge.

Just remember - bleed it out thoroughly, air in the system is bad. The reservoir on the side is just that, a reservoir. If there's air in the top of the radiator, but the fluid is below what there is on the reservoir, it WILL NOT fill the engine. You must bleed it out through that hole.

Check this thread: http://forums.bimmerforums.com/forum...d.php?t=470644 and read my last post. The antifreeze choice is yours, but if you just want to be safe, the BMW coolant isn't to expensive.

DEATH2000 · 06-27-2006, 12:06 AM

Were is the bleeder valve located? And i think the hose wasnt clamped tight enough and thats why it poped off, might have been the thermostat but i dunno yet.

**Dudesky** · 06-27-2006, 05:40 AM

Bleeder screw is just to the right of the coolant cap, has a cross on it, and says "ENTLUFTUNG" around it. Look at figure 2 in the Pelican Parts article.

DEATH2000 · 06-29-2006, 12:16 PM

Well my car is even more fuked than i thought. So the mechanic i took it to replaced the thermostat and the water pump cause the seal was about to go. And it still overheats. So hes thinking maybe the clutch fan cause its not engaging. If its not that what could it be?

**c1apton** · 06-29-2006, 12:28 PM

Have him pressure test your cooling system. (pressure test with pump, etc) If it leaks down & doesn't hold pressure you have yourself a "cooked" headgasket. I'm assuming this mechanic knows to bleed the system (if he's not up on BMWs - they usually don't know to do it) It's possibly a fan clutch but before you throw more ca$h at it, have him pressure test the system.

DEATH2000 · 06-29-2006, 12:35 PM

Ok thanks C1apton. If it is a cooked headgasket ill use this chance to get an M50 manifold