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E39 (1997 - 2003)
The BMW 5-Series (E39 chassis) was introduced in the United States as a 1997 model year car and lasted until the 2004 when the E60 chassis was released. The United States saw several variations including the 525i, 528i, 530i and 540i. -- View the E39 Wiki

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  #1  
Old 07-01-2012, 01:03 AM
mkc5150 mkc5150 is offline
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Location: St. Louis, MO
 
Join Date: Jul 2012
Posts: 7
Mein Auto: 2002 530i E39
Exclamation Trying to replicate coolant sys problem....

Ok gang, so my 5 series has been leaking anti-freeze for about 6 months now. I've been topping the coolant level off every so often to alleviate the OBD indicator to check coolant level. The other day, (100 degrees F here in the LOU) unexpectedly I was idling at a drive through with the AC on, and the digital "CHECK COOLANT TEMP" message displayed in the dash.

I noticed that the analog temp display in the dash rapidly went from the middle of the gauge where it normally sits, to the red end of the temp spectrum. So, I immediately turned the AC off, dialed the temperature for the interior heating system up to 90 degrees, and forced all of the air through the front defrost vents. This almost immediately remedied the over-heating problem. The analog gauge returned to the half way mark between cold and hot; and the digital OBD message disappeared.

Since then, I have been reluctant to drive the car, for two reasons: one, I don't want it to cause damage by overheating; two, it's too damn hot to be driving around St. Louis with the heater on when it's nearly 110 with the heat index factored in!

Also, I cleaned the engine bay out with a mild engine cleaner about a month ago. Now, I notice that there is some over-spray of what looks to be engine coolant all around the front of the engine bay---near the radiator and surrounding components.

Up to today: I have tried to duplicate the issue by idling with the AC on, even holding red-line on the tach to try and get the problem to reoccur. No such luck. But I do smell a peculiar odor in the engine bay...today I checked the coolant level, and it seemed to be on the low side, so I added more coolant to top the level off. Shortly there after, the "CHECK COOLANT LEVEL" message displayed in the OBD dashboard. Later, this evening, after a 5 minute drive home from the local pub, I removed the cap from the radiator/expansion tank, and immediately, coolant began to over-flow from the reservoir....

The "CHECK COOLANT LEVEL" message is still being displayed, and I'm frustrated as all get out. Could this be a stuck thermostat issue? Water pump? Leaking hoses? Even a faulty temp sensor?

I had auto-zone do a code read on the vehicle, and there were no stored faults, nor are there any 'check engine' lights on...

Any and all suggestions/help is greatly appreciated!

THANKS!

Mike Coffer

e39 530i 2002--114k
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  #2  
Old 07-01-2012, 02:39 AM
loudbmw loudbmw is offline
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Location: Virginia
 
Join Date: Sep 2010
Posts: 13
Mein Auto: 530i E350 C320
I have same year and mileage as you as well as owned a '99 528i. I assume you haven't done a cooling system rebuild. At around 100K miles, the cooling system starts to leak. You could do what I did the first time and start changing parts as they fail. But after pulling the radiator 3 times for 1) a leaking radiator 2) leaking water pump 3) fan clutch I gave up and changed all three at the same time on my 2002 530i.

As long as you're at it, change all the hoses, belt idlers and thermostat. It's about $500 in parts if you can manage it yourself but your cooling worries will be over for another 100K miles.
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  #3  
Old 07-01-2012, 06:13 AM
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mmm635 mmm635 is offline
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Location: Jackson, MS
 
Join Date: Mar 2005
Posts: 1,179
Mein Auto: '02 525i Sp/5, 95 FJ80 LC
Quote:
Originally Posted by mkc5150 View Post
Ok gang, so my 5 series has been leaking anti-freeze for about 6 months now. I've been topping the coolant level off every so often to alleviate the OBD indicator to check coolant level. The other day, (100 degrees F here in the LOU) unexpectedly I was idling at a drive through with the AC on, and the digital "CHECK COOLANT TEMP" message displayed in the dash.

I noticed that the analog temp display in the dash rapidly went from the middle of the gauge where it normally sits, to the red end of the temp spectrum. So, I immediately turned the AC off, dialed the temperature for the interior heating system up to 90 degrees, and forced all of the air through the front defrost vents. This almost immediately remedied the over-heating problem. The analog gauge returned to the half way mark between cold and hot; and the digital OBD message disappeared.

Since then, I have been reluctant to drive the car, for two reasons: one, I don't want it to cause damage by overheating; two, it's too damn hot to be driving around St. Louis with the heater on when it's nearly 110 with the heat index factored in!

Also, I cleaned the engine bay out with a mild engine cleaner about a month ago. Now, I notice that there is some over-spray of what looks to be engine coolant all around the front of the engine bay---near the radiator and surrounding components.

Up to today: I have tried to duplicate the issue by idling with the AC on, even holding red-line on the tach to try and get the problem to reoccur. No such luck. But I do smell a peculiar odor in the engine bay...today I checked the coolant level, and it seemed to be on the low side, so I added more coolant to top the level off. Shortly there after, the "CHECK COOLANT LEVEL" message displayed in the OBD dashboard. Later, this evening, after a 5 minute drive home from the local pub, I removed the cap from the radiator/expansion tank, and immediately, coolant began to over-flow from the reservoir....

The "CHECK COOLANT LEVEL" message is still being displayed, and I'm frustrated as all get out. Could this be a stuck thermostat issue? Water pump? Leaking hoses? Even a faulty temp sensor?

I had auto-zone do a code read on the vehicle, and there were no stored faults, nor are there any 'check engine' lights on...

Any and all suggestions/help is greatly appreciated!

THANKS!

Mike Coffer

e39 530i 2002--114k
From what you describe, you might have a thermostat sticking.

Also, check underneath the water pump for any visible signs of leaks. It can leak very slowly there, fall on to the underbody protection and evaporate before you see it.
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  #4  
Old 07-01-2012, 08:05 AM
jglover jglover is offline
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Location: Fairfield, California
 
Join Date: Sep 2005
Posts: 445
Mein Auto: 2000 528i
I have experienced the same sort of problem you have discribed. I was sitting at a stop light when my temp gauge which was sitting at normal went straight to red. I kicked the trans in to neatural and gave the engine a few revs. The temp gauge returned to normal and new missed a beat after that. This happened on a 49 degree morning in the beautiful Napa Valley. Although i never got coolant warning light, I did change the water pump, thermostat, clutch fan, and hose for safety. When I went to do the repairs, I found that the water pump had a "slow leak". What ever was leaking had been coming out of the relief hole on the water pump and been flung around by the crank pulley and was forming some weird white deposit over the front of the engine. I had a icecicle growing from the underside of the thermostat house. Have pic of it but not good at posting pic. Since replacing part all good but still nervous since I have had the cylinder head replace some years ago and still have shell shock from the process.
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  #5  
Old 07-01-2012, 08:48 AM
edjack edjack is offline
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Location: San Jose, CA
 
Join Date: May 2007
Posts: 9,203
Mein Auto: '97 540i 6 speed
The stick and float that measures coolant level is of a different plastic, and is one of the first components to disintegrate. Does it still float when you top up?

When you have a leak, you get air pockets in the cooling system.

If the cooling system is original (date sticker on the rad), it's best to overhaul it pronto. Remember, the six is much more sensitive to an overheat than is the V8, and you run the very real danger of damaging the engine.
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