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Discussion Starter #1
Greetings
I did a casual search of the forum to find an answer to my particular problem but didn't,
so I hope to do so with this thread.
Today, I had my very first overheating event. It wasn't your typical 105 degree Tucson Arizona
morning because of the Monsoon season rains, it was only in the 80's. For the first time, my car overheated and I quickly shut it off. The pressure relief port on top of the radiator next to the cap was spewing, so it looked to be doing it's job. Once the engine cooled for a bit, I was able to remove the cap without spewing coolant. The water level was not low and the red indicator rod floated to the top. I did not see or smell antifreeze. The water looked a little foamy but not much, and certainly didn't have the usual color with coolant added. I attempted to add water while the engine was running (gauge at center) and it took a little bit but quickly heated up again.
I let it sit for a while and with the cap off I decided to pour water onto the engine to assist in cooling it down and all of a sudden the water level dropped quickly in the radiator. I quickly filled the radiator with more water until it topped off. I closed the cap and let it idle for a bit.
The needle stayed at the center for about 5 minutes and then started rising in temperature.
Now, this was a behavior I associated with older American cars where the mechanical thermostat on the water jacket/ manifold inlet had failed, not letting any water through.
But being this not the same animal, I am left to believe it may be something more involved or is it?
No visible leaks yet and waiting until I can get the proper coolant to do the service. Flush, bleed and fill with proper mixture.
What do I need to know and can anyone assist me here?
I appreciate your taking the time to read my lengthy post.
Thank you,
Billy
 

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Discussion Starter #2
Update

I just added close to a gallon of water after the car had cooled down considerably.
It started just fine and I ran it up to 2500 RPM for about 5 minutes and the gauge
never rose above center. So, I can assume that it's just time for a cooling system
service. The radiator is not leaking but that pressure relief port next to the cap
bothers me, as it bubbles quite a bit. Also, the fan shroud has a tap that acts as a
mounting point for the reservoir tank. It has cracked and broken away, so I need
to repair that. I am not sure about whether my car had the plastic radiator problem
that I had seen postings about before.
It's time for me to research.
Thanks again.
Billy
 

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I decided to pour water onto the engine to assist in cooling it down
this is dangerous, hot metal can crack if you pour cold water on it
 

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The radiator is not leaking but that pressure relief port
Maybe my memory is wrong but I'm not aware of an extra pressure relief port. It's integrated into the expansion tank cap. Sounds like your bleeder screw is leaking.
 

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Wingnut
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but that pressure relief port next to the cap
bothers me, as it bubbles quite a bit.
Billy
o ring leaking on the bleed port (what you had called the pressure relief port) or the screw is damaged. that in itself is a coolant leak, refilling these machines properly takes more than just filling 'er up with water. the air must be properly bled from the system thru the bleed port(s). how long have you had the car, and what cooling system service has been done up til now?
 

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As Matt has said, that's not a pressure relief valve, that's used to bleed the system.

You have a leak, not sure if it's only the O-ring on the tank, or there are other leaks. You might start with a pressure test, after replacing the O-ring to make sure that is the only leak, and go from there. Could be only that or as you noted, could be the thermostat, or it also could be the water pump, even a clogged radiator, or even all the above.

You have to start somewhere, replace the O-ring and pressure test after would be a good start.

A proper mix of h2O and antifreeze is essential for several reasons. Be sure you are using it in the cooling system.

Jim
 

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As Matt has said, that's not a pressure relief valve, that's used to bleed the system.

You have a leak, not sure if it's only the O-ring on the tank, or there are other leaks. You might start with a pressure test, after replacing the O-ring to make sure that is the only leak, and go from there. Could be only that or as you noted, could be the thermostat, or it also could be the water pump, even a clogged radiator, or even all the above.

You have to start somewhere, replace the O-ring and pressure test after would be a good start.

A proper mix of h2O and antifreeze is essential for several reasons. Be sure you are using it in the cooling system.

Jim
Distilled water is a better option and easier to acquire in a pinch. Don't
just dump any antifreeze in there. Antifreeze is called antifreeze for a reason...
you can add that later; BMW brand, once you have fixed the problem....not that crucial
in a warm climate until you get things worked out. I'd rather dump a bunch of distilled water
into my cooling system than a mix of off brand coolant. I carry a two jugs of
pre-mixed BMW coolant always...Reverend..!
 

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Under the lift arms
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Id recommend a New Main fan clutch a brass bleeder upgrade and new cap

start with that,

Depending on your mileage you might want to consider a new Tank and or some hose,
Its not as bad as people make it seem... you just cant be tooling along with the radio on while the car is DONG'n! to death
 

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Distilled water is a better option and easier to acquire in a pinch. Don't
just dump any antifreeze in there. Antifreeze is called antifreeze for a reason...
you can add that later; BMW brand, once you have fixed the problem....not that crucial
in a warm climate until you get things worked out. I'd rather dump a bunch of distilled water
into my cooling system than a mix of off brand coolant. I carry a two jugs of
pre-mixed BMW coolant always...Reverend..!
Good point, however I look at it a little differently. Distilled water is cheaper, but also has a lower boiling point than does antifreeze, which could be called antifreeze/antiboil, but it's just not as catchy. Also, once you have diluted the cooling system with water, you're going to have to bleed off quite a bit to get back to a good 50/50 mix when the system is repaired.

Do you expect to lose more than a gallon? If so, you're probably talking pulling the rad, so then are you going to refill with h2O in case it leaks more?

But then again, I'm one of those heretics who uses Prestone 50/50.

Jim
 

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Wingnut
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But then again, I'm one of those heretics who uses Prestone 50/50.

Jim
almost a ditto...i use the full strength, figured the 50/50 mixture based on system capacity when i did my system overhaul, then carry a jug premixed in my trunk just in case.
 

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Discussion Starter #12
o ring leaking on the bleed port (what you had called the pressure relief port) or the screw is damaged. that in itself is a coolant leak, refilling these machines properly takes more than just filling 'er up with water. the air must be properly bled from the system thru the bleed port(s). how long have you had the car, and what cooling system service has been done up til now?
My car was purchased 5 years ago. It's been routinely serviced and has never had any issue concerning cooling. It currently has 120K miles on it and runs strong.
IF you could be so kind, point me to a video or resource for addressing the O ring and bleeding of the system, or should I say restoring the level of coolant. I am currently not using the car and am out of town at the moment.
BIG THANKS to all who replied.
Billy
 

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INSANELY UNPREDICTABLE!
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Did the car overheat while sitting idle (traffic) or while moving?

If idle I would check to make sure you aux fan is operating properly if at all.

If while moving (40 mph or faster) could be a few other items. Based on the year and BMW's reputation for faulty aux fans I would start there.
 

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Discussion Starter #14
Did the car overheat while sitting idle (traffic) or while moving?

If idle I would check to make sure you aux fan is operating properly if at all.

If while moving (40 mph or faster) could be a few other items. Based on the year and BMW's reputation for faulty aux fans I would start there.
When the instrumentation alerted me, I was sitting at a traffic light after driving 45+ mph.
So, both. The aux fan works fine.
 

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My car was purchased 5 years ago. It's been routinely serviced and has never had any issue concerning cooling. It currently has 120K miles on it and runs strong.
IF you could be so kind, point me to a video or resource for addressing the O ring and bleeding of the system, or should I say restoring the level of coolant. I am currently not using the car and am out of town at the moment.
BIG THANKS to all who replied.
Billy
There is an immense amount of great info available here. Up at the top of each page you will see, on the right hand side, a search box, there you will find everything you need and then some.

Here is a sample that might help you.
http://www.bimmerfest.com/forums/showthread.php?t=558386

Please be aware, the cooling system in these cars is a weak point. Be sure to examine it upon occasion. Look for bulging around the clamp areas.

The O-ring is a simple affair, you can pick up a whole brass screw on e-bay quite reasonably, and the O-ring is included.

You will likely need a cooling system overhaul in the not to distant future. Would be wise to read up on it and see what and why.

Jim
 

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Discussion Starter #16
there is an immense amount of great info available here. Up at the top of each page you will see, on the right hand side, a search box, there you will find everything you need and then some.

Here is a sample that might help you.
http://www.bimmerfest.com/forums/showthread.php?t=558386

please be aware, the cooling system in these cars is a weak point. Be sure to examine it upon occasion. Look for bulging around the clamp areas.

The o-ring is a simple affair, you can pick up a whole brass screw on e-bay quite reasonably, and the o-ring is included.

You will likely need a cooling system overhaul in the not to distant future. Would be wise to read up on it and see what and why.

Jim
thanks!
 

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INSANELY UNPREDICTABLE!
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When the instrumentation alerted me, I was sitting at a traffic light after driving 45+ mph.
So, both. The aux fan works fine.
You have tested it? You have waited to see it actually turns on? Not to be confused with the clutch fan.

If both of these fans check out, i would replace the thermostat and properly bleed the coolant system and hole for thr best. If no cooling system work has been done to this car recently this is a cheap and usually effective way to deal with overheating issues. Unless you have a blown headgasket (also common on m50/52) engines)
 

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Discussion Starter #18
You have tested it? You have waited to see it actually turns on? Not to be confused with the clutch fan.

If both of these fans check out, i would replace the thermostat and properly bleed the coolant system and hole for thr best. If no cooling system work has been done to this car recently this is a cheap and usually effective way to deal with overheating issues. Unless you have a blown headgasket (also common on m50/52) engines)
The engine is okay, in that it's behaving fine. I found the leak area around the underside of the radiator. I got home today and took it for a drive. It didn't overheat and the gauge stayed right where it should. With that in mind, I assume the thermostat to be good. So, the leak scenario makes sense as to the cause of the overheating. I only noticed water under the car once before and it was clear, so I suspected it was the air conditioner draining water like they do. If I had noticed any color I would have been alarmed to the coolant. This bothers me because it appears that perhaps there was no antifreeze/antiboil additive to begin with.
My assumptions could really be a bad thing!
The links to the videos are a huge help and I really appreciate the help. I will follow the advice and in particular, will do the specified cooling system servicing and replace anything that needs
to be replaced.
I will certainly post my findings here in case anyone is curious.
BIG THANKS!!!
 

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The engine is okay, in that it's behaving fine. I found the leak area around the underside of the radiator. I got home today and took it for a drive. It didn't overheat and the gauge stayed right where it should. With that in mind, I assume the thermostat to be good. So, the leak scenario makes sense as to the cause of the overheating. I only noticed water under the car once before and it was clear, so I suspected it was the air conditioner draining water like they do. If I had noticed any color I would have been alarmed to the coolant. This bothers me because it appears that perhaps there was no antifreeze/antiboil additive to begin with.
My assumptions could really be a bad thing!
The links to the videos are a huge help and I really appreciate the help. I will follow the advice and in particular, will do the specified cooling system servicing and replace anything that needs
to be replaced.
I will certainly post my findings here in case anyone is curious.
BIG THANKS!!!
Looks like you got it figured out! That's great! A leak will certainly cause your overheating problem. Make sure to source a quality radiator for replacement.
 

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Discussion Starter #20
Thanks to all who helped.
The problem has been sorted out. The bleed screw next to the expansion tank cap was broken, sheared off by someone
attempting to loosen it before I bought the car. Under pressure, it was leaking from there.
I replaced it and the other one on the water thermostat body. I performed
the bleed procedure and its fine now, runs cool as a cucumber so to speak.
However, I am noticing a small steady drip of clear water back by the rear transmission housing.
I thought maybe that was the air conditioner draining but
I am not sure. I turned the AC off and let it run awhile and the drip remains.
So, I am going to see my mechanic and get the car up on a lift to inspect to see where it's coming from.
I'll keep you posted but in the meantime, does this make sense to anyone here, perhaps shed some light
on what might be causing this?
Thanks again.
Billy in Tucson.
 
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