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Old 10-20-2017, 08:43 AM   #1
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Join Date: Oct 2017
Location: michigan
Posts: 1
My Ride: bmw/330ci,325ci,k120
cooling conundrum

I have searched and read and while many have same/similar problems I am still searching.

As a preventative measure I change thermostat and water pump in my 330ci (manual trans).

Shes a garage queen. Everything seemed fine then at idle one day it was overheating slightly. Needle went just north of middle. Upon driving home needle went back to center-air flowing over system. Checked upper and lower radiator hoses by hand and with thermometer. Upper was hot, lower could hold no problem. Bled system again. No change. Took thermostat off and discovered it was bad. New one installed. Hoses both hot, BUT. Still creeping needle. Turned on hidden dash functions to watch temp. Driving its 97-98c. Got home both hoses nice and hot. Sitting at idle though, needle crept north digital temp went into low hundreds (105 I shut it down).

Checked Ohms at hot v cold at lower radiator coolant temp. sensor. Had 200 Ohm difference.

Discovered fan not working. Had power to it (at plug) could jump motor direct but found the module at back of fan near motor was dead. New one installed. I can jump power to it at plug and make fan turn on so I know fan works.

Have 12v power at plug coming to fan with car off so I know there is power.

Tried unplugging coolant temp sensor and running car and A/C. Fan would not come on.

Tried all the tricks I read here. Even swore, prayed, hopped on one foot, I may have even kicked the bumper. Nothing.

What am I missing or should I try???
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Old 10-20-2017, 08:53 AM   #2
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Join Date: Aug 2016
Location: Connecticut
Posts: 276
My Ride: 325i Touring 5spd
Year: 2002
Model: 325i
Transmission: Getrag 250g
So it sounds like the issue is just your fan not coming on? I just did the mechanical to electronic fan swap in my car and couldn't get the thing to turn on either. I just ended up taking all of the 50A fuses out one by one (since I didn't know which was the correct one) and inspected them. They were all fine but when I plugged them back in the fan started working correctly, then. That probably doesn't help you out too much but, since you didn't mention it, did you check the fuses?

The bumper is mostly metal so she can take a kick or two
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Old 10-21-2017, 07:31 AM   #3
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Join Date: Jul 2008
Location: USA
Posts: 9,674
My Ride: 2018 M240i
Read this:
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Old 10-21-2017, 11:27 AM   #4
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Join Date: Jan 2012
Location: car-nation
Posts: 1,630
My Ride: 2004xit, 2001ci
Sounds like your fan contoller is still bad. They have a bad habit of doing that, recently, it seems...

OR- check the small wires going into the plug for it carefully, especially the green with black stripe (I think) one.

I have found this one broken several times- in fact, on Jenn's car, it physically separated on its own.
If I hadn't known that the hood had never been opened about the time it failed, I would have suspected sabotage.
My theory is that the jig at Munich was off a little bit, and this small wire ends up taking the strain
of the whole harness and fatigues. Since then, I've seen several at the junkyards with this problem, too.

It's hard to spot, sometimes- you have to give a reasonable tug on the wire, and then the insulation
will stretch where the copper conductor's failed.

Something to check,
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