Engine overheating

PAISITAG

MEMBER
2003 BMW 325I
2.5L
6 CYL
4WD
AUTOMATIC
250,000 MILES

So I changed my lower radiator hose because it was leaking coolant and after I went for a ride, I saw that my temperature needle went high enough to the red part. After my car cooled down I bleed the system (with the bleed screw off of the upper radiator hose) and my car kept overheating so I tried to bleed it again but instead of using the bleeder screw I left my radiator cap off and started the car, at first I saw some bubbles coming from the tank but after a while it started to overflow and it was kind of boiling. I've even flush my coolant system and this keeps happening. Can you guys help me out with this?

BMW E46

7 Replies

PAISITAG

MEMBER
5 POSTS

This is a video I recorded.

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Wednesday, May 26th, 2021 AT 6:29 PM

JACOBANDNICKOLAS

MECHANIC
108,179 POSTS

Hi,

When you bled the system, did you have the heater on? If you don't, it won't actuate the auxiliary water pump. Do me a favor. Take a look at the directions below. These are the specific directions for bleeding the cooling system on this vehicle. Let me know if this is what was done. If it wasn't, try it and let me know if it helps.

Take care,

Joe

See pics below.

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Wednesday, May 26th, 2021 AT 8:50 PM

PAISITAG

MEMBER
5 POSTS

Hey,

I did everything you told me to do but my engine keeps overheating. I noticed that this time the lower radiator hose was almost cold and the upper radiator hose was very hot (other days both were hot). My coolant temperature was 121 and I turned the engine off, my coolant reservoir cap was cold too.

Thanks for the replay you gave me and I hope you can help me out with this.

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Thursday, May 27th, 2021 AT 6:34 PM

JACOBANDNICKOLAS

MECHANIC
108,179 POSTS

Hi,

Since this has an automatic transmission, the cooling system is equipped with a fan clutch driven by the serpentine belt. When the engine is hot, It should lock up and make enough noise to hear it. Do you notice anything? Does the vehicle overheat at highway speeds? Have you noticed the electric cooling fans turning on?

Let me know.

Joe

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Thursday, May 27th, 2021 AT 8:28 PM

PAISITAG

MEMBER
5 POSTS

Hey Joe,

Yesterday the auxiliary fan did not turn on when the engine was getting hot but today it did. So I went for a ride and my temperature needle was fluctuating between the red mark and the middle, so I turned off engine and lift the hood and I saw my coolant was overflowing from the expansion tank cap (a lil bit) and it was very hot this time, also steam was coming from the cap. After I waited for like 30 minutes for the car to cool down a little bit. So when I turned my ignition and I check my coolant temperature from the dashboard it was almost cold, (I think it marked 44) knowing the car had been overheated.I turned the car again and saw that the temperature came back as it was. Any ideas about this?

Thank you for helping me out.