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Discussion Starter #1 (Edited)
(if you dont want to read the whole story, scroll down to the end)

Hi all,

First of all, I want you guys to excuse my English but it is not my native language although I understand it really well. This is my first post given the circumstance that I have not found the answer to my problem on other threads.

I have read several threads about overheated BMWs and I have done everything that e46fanatics recommended to solve the problem and still have not found what is causing the car to overheat.

One day I noticed that suddenly a lot of green liquid was on the floor and I decided to go to the mechanic. On my way there, the car overheated very quick and I turned it off and call AAA since I did not want to jeopardize the engine.

I arrived to the auto repair and they told me the fan clutch was not working properly and replaced it. They charged me $354. I thought everything was fine and went home. That day everything was perfect. The next day I started the car and within 20 minutes the car got overheated again.

I did not want to bring my 325i to the mechanic again since they did not solve the problem and only changed the fan clutch. Right now, I think they may have changed that and it was not that bad. They charged me quite a lot and I dont have enough money right now.

I decided to fix it myself. I started looking a different threads here and since the overheating occurs very quick, I thought I could be the thermostat (stat). So, I went to Autozone and got the original one for $90 (I could have ordered the one with aluminium gasket online, but since I wanted to solve it ASAP, I bought that one at Autozone). I follow several tutorials to remove everything and reach the thermostat and changed it successfully. My big surprise was that when I started it, it overheated again.



My next step was to check that water pump (which I should have done when I changed the thermostat), but before doing that I decided to check if there was air in the cooling system, and it was. I drained the air and the overheating was gone for 1 Hour. The electric fan was working so I figured out that the hose that goes from the thermostat to the radiator was hot (which I think that is what turns the electric fan on).

I was very happy with my first DIY.
However, the next day I was driving to sears to buy something for my next project (change the seals in the VANOS) when the car overheated again.
The hose that I was talking about was not hot which leads me to believe that the coolant was nor circulating in the cooling system.


This morning I took the water pump out and it was perfect (a little bit rusty) but overall looked good. I doubt the rusty propel may be causing the car to overheated. I put it again there but I have not put the main (mechanic) fan or start the engine.



Please, please.... can you help me out to figure out what the problem is. And how to check something else.
Thank you guys....

SUMMARY:
The car overheats very quick after reaching normal temperature.
I changed the stat and checked the water pump and it was ok.
The hose that goes from the stat to the radiator remains cold, so the coolant is not circulating.

What possible thing may be causing this (excluding thermostat and water pump)?

RaCeS 1986
 

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Discussion Starter #3
Hi CyclonRed,

I am very new in this forum and I did not understand the linked that you just posted.
What does that mean?

Races
 

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Hi CyclonRed,

I am very new in this forum and I did not understand the linked that you just posted.
What does that mean?

Races
I'm not sure what he meant either, but you seem to have touched on most of the "usual suspects". Replacing your thermostat and water pump is good preventative maintenance anyway.

Try using the search feature above and type in "overheating".

Sorry I can't help any further, replacing the electric fan solved my problem a few months ago.
 

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Discussion Starter #6
Hi all,
First of all, thank you for your great replies. I bled the system correctly and it looks like it is not overheating anymore.
However, the last time it was ok the first day and overheated the next day.

I am going to copy and paste the correct bleeding procedure that I got from Smolck in bimmerfest.com
"Leave the car running with the cap off and bleed screw open. Turn your heater on full blast set to 91 degrees and the three red dots on the center vent. It is best to have it on defrost (blowing at windshield). Pour coolant slowly till it starts coming out the bleed screw. Tighten the screw and cap the radiator. No mor air bubbles"

Thank you

Races
 

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When you bleed the coolant with your cap open, leave it running until you see no more bubbles before closing cap.
 

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Discussion Starter #8
Hi Verg64,

I bled the cooling system twice and it doe snot overheat more.
I found incredible how a bleeding problem can cause so many problems.

I took me 3 days to figure out that the whole overheating was being caused by a poor bleeding procedure.
 
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