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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 07-18-2015, 08:23 AM
emack23 emack23 is offline
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Mein Auto: 1998 BMW 528i
Overheating

Hi everyone. I bought a 1998 BMW 528i with 174,000 miles on it. Car is in perfect shape the previous owner did a lot of work and has reciepts to prove. Anyways the other day I was driving down the highway and I look down at my temp gauge it was all the way on HOT so I pull over to a gas station turn off the car pop the hood and smoke is coming out I look around and see the hose to the water pump is off. The mechanic there tightens the screw and I drive home. I call my
Mechanic and he says there's air in the system. So I let the car cool next day after work I "burp" the car. Turn it on let it idle and then it blows off again! Took it to my mechanic he did a pressure test he said there's no leaks he also replaced the clamp on the hose. He also told me the AC fan doesn't turn on and that is one reason my car overheated. I was running the AC the whole day because it was hot! I just want to know if he is telling me the truth
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  #2  
Old 07-18-2015, 09:15 AM
edjack edjack is offline
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Your MY aux fan should come on when the A/C is on. Have it looked at.

The I6 is difficult to bleed the air out.

Bleed cooling system 6 cyl via cn90

Nothing new, but the cooling system on the 6-cylinder engines has baffled me for a long time, why it is too difficult to bleed the air out etc.

So I will do a short and sweet DIY for those who wonder how to fill the coolant after performing cooling system work (such as cooling overhaul or water pump replacement etc.).

1. Take a minute to study the design of the E39 cooling system (see figure below). When the car is cold in the morning and you start the engine: during the warm-up phase, there is some hot coolant getting into the driver's side hose, "ready" to go through the radiator once the thermostat is open. Think about the thermostat as the "flood gate".

2. Now once the thermostat is open, the flow direction is:
Engine ---> driver's side hose ---> upper radiator ---> across radiator (to be cooled down)---> lower radiator hose ---> through thermostat area ---> Water Pump to cool engine.

- So in a normal engine at operating temp, the lower hose is considered the "Cold" side because the coolant has been cooled by the radiator but it is still somewhat "Hot" to the human hand anyway (maybe around 60-70 deg C, enough to burn your skin!). Here is the direction of coolant flow (from M54 but M52 flow is the same):

Study this M54 layout:




3. After some work in the cooling system is performed, re-filling the system is tricky because of the goofy design.
I just took another detailed look at my car again and here is the trick.

- Normally (if you haven't done any work on the cooling system at all) you want coolant at "KALT" level (or COLD level in the morning), but during re-filling, don't worry about it for now.

- Look at the thermostat housing, there is a small hole connecting the right and left sides of the thermostat housing. This hole allows air trapped in the lower radiator hose to travel through the hole to the driver's side to be bled out the bleeder screw.
(See GREEN arrow in pic below).

- If your car is on level ground, look carefully, you will see that the thermostat housing bleed screw (#1) is located at the reservoir neck and not at the "KALT" mark on the reservoir.

- Once you understand the above design, re-filling is easy.

a- Fiil coolant slowly. But I will add some tips...

b- Be patient and be patient, the hole connecting the (R) and (L) sides the thermostat housing is very small, maybe 1/16" or something like it. So air bubbles move through it very slowly.

c- Fill coolant up to the reservoir neck until it stops filling. Now some air is trapped in the lower radiator hose. Give it a good 5 minutes to settle there. Fill again until coolant fills to the neck, which is about 3 inches above "KALT" mark.

In the mean time, listen to some music and drink some beer...

d- Now open the thermostat housing 1 full turn (it takes 5 full turns to remove the bleed screw, so 1 full turn is all you need), air will come out slowly because the hole in the tstat housing is very small. When coolant comes out, close the bleed screw.

e- Don't start the engine yet, repeat the steps a through d a few times (another beer won't hurt... ) until you are sure all air is bled out of the bleed screw.

f- For the 1st fill, if coolant is at the reservoir neck, then it is OK, air trapped in the engine will be expelled out when you run the engine. It will eventually settle down to "KALT" level anyway. If you are worried, then use a turkey baster to remove a bit coolant so it sits just below the neck prior to running the engine.

This should do it. Be patient and be patient when filling the cooling system!!!

4. The above little trick will help get rid of air outside of the engine.
Air Lock (air trapped inside the engine behind the thermostat) is another issue. Do a search.





howdy c90,i had an e34 m20b25 and currently a '97 528i m52b28.this is how i bleed my cars with ease and success all the time:

1. open both bleeder screws
2. fill up radiator with water till full
3. close radiator bleeder screw
4. blow into radiator filler neck till water comes out of engine bleeder port.ensure nil air bubbles.tighten engine bleeder screw
5. top up water if required
6. blow again till water comes out of radiator bleeder port.ensure nil bubbles.tighten radiator bleeder screw.
7. you're done.
8.to fill coolant,drain the reservoir tilll empty and fill up with coolant.no bleeding required.
9. step 6 will require you to top up water approx twice
10.i live at the equator so coolant used more for water pump lube and antirust purposes

cheers
________________________________________
Last edited by moots; Today at 09:49 AM.
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  #3  
Old 07-18-2015, 09:33 AM
emack23 emack23 is offline
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Ok thank you for ur response! But my question is because my AC fan doesn't come on does that cause over heating?
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  #4  
Old 07-18-2015, 09:37 AM
edjack edjack is offline
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It can. The aux fan is a "helper" for the mechanical fan when using the A/C. Later MYs use a thermostatically-controlled variable speed aux fan.
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  #5  
Old 07-18-2015, 09:44 AM
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Wgosma Wgosma is online now
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Not a 100 pct certainty, but very likely the cause....if the rest of the cooling system is known to be fully functional you could test drive with a/c turned off and see how it responds- bring engine up to temp in your driveway and observe temp gauge for couple of minutes before putting the car in gear and going for a drive. Cooling systems on these cars require regular PM to insure they remain operationally solid- the motors do not withstand overheating well, shut the car off right away if that temp needle starts moving towards the red zone.
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  #6  
Old 07-19-2015, 02:57 AM
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mjalloul11 mjalloul11 is offline
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The AUX fan does nothing when the car is moving at a steady speed and should not come on unles you have a problem. The AUX fan IS importent in slow speed and heavy trafic. It looks you have a problem maybe a cloged rad?
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Old 07-19-2015, 01:19 PM
edjack edjack is offline
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Quote:
Originally Posted by mjalloul11 View Post
The AUX fan does nothing when the car is moving at a steady speed and should not come on unles you have a problem. The AUX fan IS importent in slow speed and heavy trafic. It looks you have a problem maybe a cloged rad?
You must have a different IHKA panel than the one fitted to North American cars. The '97-'98 NA models work as I stated above. On the '99+ models, the aux fan is controlled by the LKM, and is only comes on when needed, whether the A/C is engaged or not.
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Last edited by edjack; 07-19-2015 at 01:20 PM.
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  #8  
Old 07-19-2015, 02:00 PM
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mjalloul11 mjalloul11 is offline
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On 96 to 98 models the AUX fan is controled by two things, one is the AC panel andthe fan is on when the AC is on and the other is with the temp switch on the side of the radiator and only coes on when the temp is high enough in low or high speed. The op has a 98 model with the rezistor type one.
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  #9  
Old 07-19-2015, 10:40 PM
emack23 emack23 is offline
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My mechanic said he did a pressure test and everything was holding pressure he told me that he needed to change the fan behind my bumper. The previous owner had the whole cooling system replaced from the fan fan clutch thermostat thermostat house and water pump. I just don't want to get ripped off. So when the guy sold me the car he gave me all the receipts so I took it to the same
Mechanic because he knows the car. I hope this is the problem
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  #10  
Old 07-19-2015, 10:41 PM
emack23 emack23 is offline
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My water pump hose blew off twice! So he said he replaced the clamp on that. Like I said he said that the fan was the problem so I'm trusting him
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  #11  
Old 07-20-2015, 06:55 AM
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Wgosma Wgosma is online now
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If the aux fan itself has failed it is kind of a pain to replace, front bumper has to come off, ugh. No difficult but time consuming. Good luck/Bill
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  #12  
Old 07-20-2015, 08:50 AM
emack23 emack23 is offline
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Help overheating

My mechanic is telling me that my 1998 BMW 528i is overheating because of the fan behind my bumper. He bled the system and did a pressure test. My water pump hose also blew off twice! Is this the reason why? I am going to spend a lot of money for him to replace this. The owner before me had the whole cooling system replace from the fan fan clutch thermostat and thermostat housing.
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  #13  
Old 07-20-2015, 08:51 AM
emack23 emack23 is offline
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Could that be the reason why it's over heating?
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  #14  
Old 07-20-2015, 09:15 AM
pleiades pleiades is offline
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You say a hose blew off the water pump. Which water pump are you talking about?

The engine water pump that is turned by the serpentine belt does not have any hoses.

If you are talking about one of the large hoses that come off the t-stat housing, then maybe your problem is a failed t-stat that isn't opening up at temp.

I'm talking about part #7 in this diagram.

http://realoem.com/bmw/enUS/showpart...diagId=11_1546

Last edited by pleiades; 07-20-2015 at 09:21 AM.
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  #15  
Old 07-20-2015, 11:07 AM
emack23 emack23 is offline
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Yes it's the bottom hose. Right below the over flow tank
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  #16  
Old 07-20-2015, 11:20 AM
emack23 emack23 is offline
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If ur looking at the front of the car is the bottom hose on the left
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