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Old 01-21-2015, 09:19 PM   #1
LV3series
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Please help with overheating!

Hi, guys! I apologize for posting another overheating problem. I have searched plenty of treads about this issue, but can't seam to find one that covers my problem.
I have a 2000 323Ci convertible with 167 000miles, manual transmission. Had the water pump replaced about 8 months ago and put approx. 2500 miles on it since, without any over heating problems.
The other day I noticed the temp. gauge needle raise to the 3/4 mark while driving, but it fell back to normal shortly after. This didn't happen often, but it concerned me. So I replaced the expansion tank, but that was not the problem. But while doing it, I realized the expansion tank coolant hose (11531436410) was leaking. I do believe that leak probably caused air into the system. This hose also had a gasket inside that was pretty worn out/broken, and I am fearing some piece of it may have caused a blockage...I do not know.

I have followed Mango's cold start bleeding procedure...both on level ground and with the front raised...but still overheats...actually now it happens more frequently. It goes to 3/4 stays there for 10-15 sec before falling back to normal.

- The upper radiator hose is hot, but the lower hose and radiator doesn't heat up.
- Thermostat housing is hot
- The electric fan doesn't come on (not when starting the car, not when it overheats nor using A/C)
- The electric fan fuse #37 (50amp) is good, and I also used a digital multimeter at the fan connector and I'm getting 12V ( I do understand that the fan needs a pulse from the DME in order to kick in)
- The heater works
- There are no codes stored

I think the overheating is caused by the electric fan not working/needs replaced, or the thermostat is stuck closed...or debris has a clogged passage.
At this moment I'm totally lost and therefore reaching out, before throwing $$/parts at it. I have a feeling someone probably knows the cause...
As always, greatly appreciate your feedback, guys.
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Old 01-21-2015, 09:25 PM   #2
patrickmurray2
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I've never had this happen, but I'll give it a shot. Did you replace the thermostat and also I know you said you bled the system, did you do it properly to where you had no air coming out of the bleeder screw? I recent refreshed my system, I bled it once and a week later I had to bleed it again because all the air was not out the first time, it takes a couple times to get all the air out of the system. Goodluck!
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Old 01-21-2015, 11:34 PM   #3
LV3series
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Thanks for your reply patrickmurray2!
I am letting the car cool down as we speak. I will take out the thermostat and test it later.
As for bleeding...yeah, tried several things. The one thing I don't understand with Mango's cold engine bleeding procedure...if the engine is cold, the thermostat will stay closed. Somebody else asked this question, but nobody answered it...ignition on, max heater setting and blower on low...does that open up the thermostat? I really don't think so, but hey, maybe it doesn't need to be open
Also, does the water pump turn on when ignition is in the second position?
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Old 01-21-2015, 11:39 PM   #4
patrickmurray2
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Yeah its odd how that work but it does actuality open up the thermostat. I'm not sure about the water pump though
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Old 01-21-2015, 11:57 PM   #5
LV3series
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I appreciate your feedback, patricmurray2, but I still can't wrap my brain around it...the thermostat is a very simple device, triggered by the water temperature. I found another post stating that the procedure would open the heater core, but nothing was mentioned about the thermostat.
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Old 01-22-2015, 01:33 AM   #6
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Hmmm, well what I would do is re-bleed the system make sure there is so air bubbles and make sure coolant is at the right level, these cars are easy to overfill. May I ask how exactly you are bleeding the system? It's a bit tricky first time around, you want to keep pouring coolant in the expansion tank with bleeder screw off, key in 2nd position, fan speed low, heat all the way high (91) keep pouring until coolant cones out of the bleeder hole and there is no air, let it sit for a min. And take your turkey baster and get the level just under highest level. Make sure you try that, you don't want to drive when your car gets hot yoy could end up blowing the head gasket.
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Old 01-22-2015, 01:34 AM   #7
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Also forgot to mention, if the thermostat has never been replaced, just swap it with a new one, they go bad all quite often in these cars
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Old 01-22-2015, 02:03 AM   #8
LV3series
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Trust me, I have followed the bleeding procedures down to a tee....several times.

You said you had to bleed the car twice...did your car overheat after the first time? Did the temp gauge needle behave just like mine....going to 3/4 mark, staying there for 10-15 sec, slowly going back to middle. Remember I stated the car overheating while DRIVING.

I just took off the thermostat....silly me, I thought I could take the actual thermostat out and put it in boiling water...but of course, these cars have an integrated thermostat and housing.
I give up...will just start to order parts at will. I was really hoping someone would actually be able to pinpoint the problem with the symptoms and info I provided, but hey, maybe next time

Last edited by LV3series; Yesterday at 08:49 PM. Reason: grammar
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Old 01-22-2015, 02:12 AM   #9
patrickmurray2
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My car never over heated, just had a coolant light come up then went back and re bled, it's hard to pinpoint the problem, but if I had to guess get a new thermostat and coolant temp sensor, don't really know what the problem could be other than that, I've never had problems like this because I replaced all the cooling system parts at once
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Old 01-22-2015, 03:32 AM   #10
azatabbasov
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It is the thermostat for sure because Ifor the top is hot but bottom is cold that obviously means that the thermostat is closed shut. 45$ at autozone.
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Old 01-22-2015, 03:44 AM   #11
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Might want to check the actual temperature with the OBC (option 7.0: http://forum.e46fanatics.com/showthread.php?t=239619 )

Watch what it does...the numbers should go pretty steadily up/down. If it's not staying constant, you might have a problem with the temperature sensor.

Also, have you replace the temperature sensor in the lower radiator hose? There are two temperature sensors on the car....the temperature gauge is connected to a sensor under the intake manifold. This is the "real" temperature sensor. The sensor in the lower hose controls the electric fan.

Unplug that sensor and start the car. If the fan comes on, then the sensor isn't working. If the fan still doesn't come on, then there's a problem with the fan or the wiring to it.
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Old 01-22-2015, 03:46 AM   #12
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Quote:
Originally Posted by azatabbasov View Post
It is the thermostat for sure because Ifor the top is hot but bottom is cold that obviously means that the thermostat is closed shut. 45$ at autozone.
Not necessarily. If the temperature is jumping up to 3/4 and only staying there for 10-15 seconds, it's likely that the gauge isn't reading the correct temperature and the thermostat isn't really up to temp yet.
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Old 01-22-2015, 12:27 PM   #13
sandovaltac0574
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Mine did similar but I seen smoke cone from under the intake so I replace the radiator thermostat coolant resivior tank. Happened to be the the plastic tubes that go under the intake that had a crack in it. Could check that if you want just to make sure.
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Old 01-22-2015, 03:41 PM   #14
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I also vote for thermostat issue. Sounds like it is sticking. They usually fail open, but not always.

Tstat does not need to be open when bleeding, coolant will get to both sides via the two main radiator hoses. Putting the temp to high and fan low opens the heater coolant valve so that coolant will get to the heater core.

A failing electric fan will show up most when you are idling at a stop with a fully warmed up engine. The temp will start to creep up until you start moving. With forward speed there is good flow over the rad even without the fan and it will cool back down. If your A/C is on, it will also kick off due insufficient flow over the condenser. Then come back on when you start moving again.
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Old Yesterday, 04:49 PM   #15
kornfed44
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Idk how to make my own thread can someone tell me how
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Old Yesterday, 08:35 PM   #16
LV3series
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patrickmurray2, azatabbasov, kkasson, sandovaltac0574 and havnfun328...I want to apologize for my late reply and thank you guys for your feedback at the same time. I had pretty much given up and gave in...I just ordered bunch of parts...too much, but I just wanted to be sure. This whole warm up the engine and let it cool again...doing it over several days, just drove me nuts...sorry for being impatient. My bad

New thermostat fixed it. At least for now. I am still on the fence, because I don't know what would cause it to stick closed in the first place. I took the old thermostat and ripped it apart...but no corrosion or anything like that. But hey, at least now I know it's an electric thermostat
I was leaning towards the thermostat from the get go, but I read somewhere that with a closed thermo, I wouldn't get heat from the fan, and mine did...then I realized that internet isn't always right...no heat from fan indicates thermo stuck open...right?

From doing some internet searching, the electric thermostat should have thrown a code when it's faulty...mine didn't, but then again, I went to autozone....looks like you need a proper BMW scanner to read them.

Thank you so much, kkasson for the fan testing procedures. Very much appreciated. Even though the thermo fixed the overheating, I will go ahead and test my old fan....I ordered a new on, but still in the mail system somewhere.

So what have I learned from all this:
- Have patient...e46fanatics members will come through
- the thermo is electrical and integrated to the housing...can't buy separately and test the thermo with the old "put it in boiling water"
- When bleeding, jacking up the front really helps. After installing the new thermo, I started the bleeding process with the car level...pored the coolant slowely until no more bobbles out of the bleed nipple...waited a couple of minutes and then jacked up the front. In doing so, lots of air boobles came out and the water level in the expansion tank dropped...filled it up again all the way...no boobles at bleed nipple...turkey basted some of the coolant in the expansion tank in order to prevent overfilling/too much pressure. I am currently letting the car cool, and will check level again tomorrow.

Again, thanks for the feedback/sharing of knowledge

Last edited by LV3series; Yesterday at 08:46 PM. Reason: add info
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Old Today, 03:44 AM   #17
patrickmurray2
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Glad you got it! You're very welcome
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