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Discussion Starter · #1 ·
Afternoon/morning to whoever is reading this. I’m new to this forum and I was wondering what are the possible reasons my car is still overheating. I’ve changed out the entire cooling system with new parts. I’ve replaced the radiator, auxiliary fan, fanclutch, coolant reservoir and Radiator cap, thermostat, and water pump. Additionally, I’ve bled the system properly so there’s no air.
Symptoms:
However, current problems that I have been able to notice in regards to the cooling systems include: auxiliary fan is not turning on by itself when connected to the car (I had separately wired the fan to a switch in the driver compartment and it turns on) and the radiator is cold including Lower hose. (Sometimes the thermostat opens. However, when driving the temperature goes above 3/4 and requires me to step on the gas or rev the engine at 4-5 rpm to get the thermostat to open, allowing heat gauge to lower). And when over heating, steam and Coolant comes boiling out of the tightened radiator cap
Sorry if this post is long winded, I figured the more information the better. Thanks for responding.
 

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2004 330Ci 115k miles
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16,757 Posts
To summarize, the electric fan is not working properly?

Does pressure build up inside the cooling system fairly quickly and before it warms up much, say after less than 5 minutes?

Has this engine already overheated? If yes, how far did the temp gauge needle go to the right and for how many minutes?
 

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‘89, ‘03 and ‘98 E39
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Did you have the heat turned to max temp and low fan speed in the cabin when you bled/refilled? I am learning on these cars too, but it seems like there is air somewhere, maybe drain/fill again?
 

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BMW e46 323ci (M52TUB25) / Fiat Punto mk2b
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Well, im far from being a mechanic, there is many people way more skilled than me here but, what I would do after refreshing the cooling system I would check for bubbles (there are plenty of videos in yt about the subject) and then would test the head gasket by performing a cylinder leak down test. (There is a vid by 50skid showing the procedure).

Have a nice day and let's hope you can fix that 323!
 

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2004 330Ci 115k miles
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Did you have the heat turned to max temp and low fan speed in the cabin when you bled/refilled?
Although this is BMW’s general coolant bleeding procedure, it’s not necessary on the non-M3 E46 because the heater valve is open when unpowered and there is no coolant recirculation pump.
 

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What brand thermostat did you use? I think I remember 50’s kid on YT saying if you don’t get the right OEM part that it won’t open. It sucks to fix all of that and still have the problem!
 

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Discussion Starter · #8 ·
To summarize, the electric fan is not working properly?

Does pressure build up inside the cooling system fairly quickly and before it warms up much, say after less than 5 minutes?

Has this engine already overheated? If yes, how far did the temp gauge needle go to the right and for how many minutes?
The pressure does build up quickly. And the temp gauge has gone in the red before and to the far right while I was attempting to open the gauge again by bringing the car to 4-5 rpm. As soon as it went to the FAR right I turned off the car released pressure through the screw and gave it 3 hours to cool off.
 

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Discussion Starter · #9 ·
What brand thermostat did you use? I think I remember 50’s kid on YT saying if you don’t get the right OEM part that it won’t open. It sucks to fix all of that and still have the problem!
I’ve used the duralast thermostat, original bmw thermostat taken from the junk yard, and mahle thermostat so far all with the same issue.
 

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Discussion Starter · #10 ·
Well, im far from being a mechanic, there is many people way more skilled than me here but, what I would do after refreshing the cooling system I would check for bubbles (there are plenty of videos in yt about the subject) and then would test the head gasket by performing a cylinder leak down test. (There is a vid by 50skid showing the procedure).

Have a nice day and let's hope you can fix that 323!
Thanks! I’ve been doing the bmw bleeding procedure which includes turning on the heater. I haven’t tried a head gasket test so I’ll go try that out as well.
 

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2011 335i xDrive, 2003 325xi 5spd SOLD
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The pressure does build up quickly. And the temp gauge has gone in the red before and to the far right while I was attempting to open the gauge again by bringing the car to 4-5 rpm. As soon as it went to the FAR right I turned off the car released pressure through the screw and gave it 3 hours to cool off.
Open bleed screw = just reintroduced air back into the closed systen.
 
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