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  #1  
Old 11-22-2011, 07:29 PM
gerrg gerrg is offline
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High Temp light coming on only when running AC or Heater

Hey everyone. I've tried to do some searching, and have found one post that has similar symptoms but i have some additional info. Here is the post that is similar

http://www.bimmerfest.com/forums/sho...nt+temperature

First off, i'm driving a 2006 325i

Anyways, my engine temperature light (red/yellow) is coming on after a while when i'm running either my AC or heater. i could run the AC for about an hour durring the summer, before the red temp light came on, and now that it's winter i'm using the Heater. I can only run the heater for about 10 minutes before the air coming out of the vents starts cooling and then the yellow and red temp lights comes on.

Here's what i checked today.

I ran my car for about 10 minutes, and then checked fan on the radiator and it was on and blowing hot air.

I then turned my heater on until i saw the yellow temp light. I then stopped, and felt the air coming out of the radiator fan and it was cold. the fan was running at it's max speed. If i leave the car on after i turn the heat on, the car doesn't seem to cool down at all. the radiator fan will continue to be on max speed and the air is still cold coming out of it.

After this, i let my car sit for a few minutes and then drove back to my house leaving the heater off. when i stopped, i felt the air in front of the radiator and it was warm. I then turned my heater on again and just monitored the temp coming off the radiator. After a few minutes the air coming off the radiator started to get cold.

so what it seems like to me is that when i turn on the heater, it stops the flow of fluid through the radiator, because if there was flow, then there would be warm air coming out of the fan. it also seems like no matter if i turn the heater off or not, the flow doesn't coming back through the radiator until i turn my car off.

Right now i am able to drive without the AC or heater on for any distance and the car seems to be fine. I would certainly appreciate any and all help. Thanks!
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  #2  
Old 11-22-2011, 08:11 PM
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DSXMachina DSXMachina is offline
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Interesting. I like these kinds of problems.
I assume you have checked your coolant level?

Tomorrow, before you drive the car for the first time I want you to squeeze the upper radiator hose several times. Get a good idea of it's resistance.
Then start the engine and let it idle. Do not turn on either the ac or the heater. After exactly three minutes squeeze the upper hose again. How does it feel in comparison to when you first did it (hardness, not temperature)?
Let the engine run for 10 minutes. Now feel the temperature of the upper radiator hose and the lower radiator hose. How do they compare?
After you do the 10 minute run, while the engine is still running, slowly remove the cooling system cap. If coolant starts to gush out, tighten the cap. Did coolant gush out?

Be careful dong these checks, you've got a fan which could activate at any time, and if defective, a cooling system which could be under high pressure and/or high temperature.
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Old 11-22-2011, 08:17 PM
gerrg gerrg is offline
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Thanks for the quick reply. I have checked the coolant levels and they are good right now. The first couple times the when i hate a similar problem with the AC i lost some fluid, as in i could see it around the overflow tank. I added coolant and water and topped off these levels each time. The same thing also happened with the heater the first time where i lost fluid but since i've been able to keep a good eye on it and catch it before anything over flows.

I'll preform these checks that you suggested in the morning and let you know the results. Thanks for the ideas!
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  #4  
Old 11-22-2011, 09:25 PM
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DSXMachina DSXMachina is offline
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Originally Posted by gerrg View Post
Thanks for the quick reply. I have checked the coolant levels and they are good right now. The first couple times the when i hate a similar problem with the AC i lost some fluid, as in i could see it around the overflow tank. I added coolant and water and topped off these levels each time. The same thing also happened with the heater the first time where i lost fluid but since i've been able to keep a good eye on it and catch it before anything over flows.

I'll preform these checks that you suggested in the morning and let you know the results. Thanks for the ideas!
I suspect the worst, but let's hope for the best.
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  #5  
Old 11-22-2011, 09:29 PM
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GarySL GarySL is offline
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Originally Posted by DSXMachina View Post
...Be careful dong these checks, you've got a fan which could activate at any time, and if defective, a cooling system which could be under high pressure and/or high temperature.
I hope he's careful checking the radiator fluid with that!
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  #6  
Old 11-23-2011, 06:26 AM
chuckjoga chuckjoga is offline
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Take it to the dealer or somebody with diagnostic equipement. I'll bet you that your electric water pump is going out. Mine got flakey and would "fix" itself after waiting and restarting the car. About $800 for this.

-Chuck
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  #7  
Old 11-23-2011, 10:37 AM
gerrg gerrg is offline
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DSXMachina,

so I did those checks this morning.

Before starting the car i checked the top hose, and it felt like it didn't have pressure on it, as it should.
After 3 minutes the top hose still didn't feel like it had any pressure on it (same resistance). The hose was a little warm, and the bottom hose was cool.
After 10 minutes, the top hose still didn't have any pressure on it, was warmer still, and the bottom hose was still cool.
Same thing after 15 minutes. Up to this point, the radiator fan hasn't come on yet.
After 25 minutes, i went back out and checked and the fan was running. the top hose felt pretty hot, and it seemed to have pressure on it as it was slightly harder. The bottom hose was a little warmer but not by a lot.
after 35 minutes, i checked again and the top hose was really hot now and seemed to still be harder then before i started the car. the bottom hose was warmer still, but it was cool enough that i could hold it comfortably. After this i turned the car off.

After the 10 minute mark i did open the coolant cap, but there was no pressure on the cap, and no fluid gushed out. the fluid inside didn't have any bubbles or anything either.

I'm not sure, but the top hose might have been getting warmer due to the T-stat before the fan came on, but i'm really just guessing.
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  #8  
Old 11-23-2011, 06:30 PM
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DSXMachina DSXMachina is offline
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Originally Posted by GarySL View Post
I hope he's careful checking the radiator fluid with that!
D'oh! If I had used Mozilla, spellcheck would have picked that up.


Quote:
Originally Posted by gerrg View Post
DSXMachina,

so I did those checks this morning.

Before starting the car i checked the top hose, and it felt like it didn't have pressure on it, as it should.
After 3 minutes the top hose still didn't feel like it had any pressure on it (same resistance). The hose was a little warm, and the bottom hose was cool.
After 10 minutes, the top hose still didn't have any pressure on it, was warmer still, and the bottom hose was still cool.
Same thing after 15 minutes. Up to this point, the radiator fan hasn't come on yet.
After 25 minutes, i went back out and checked and the fan was running. the top hose felt pretty hot, and it seemed to have pressure on it as it was slightly harder. The bottom hose was a little warmer but not by a lot.
after 35 minutes, i checked again and the top hose was really hot now and seemed to still be harder then before i started the car. the bottom hose was warmer still, but it was cool enough that i could hold it comfortably. After this i turned the car off.

After the 10 minute mark i did open the coolant cap, but there was no pressure on the cap, and no fluid gushed out. the fluid inside didn't have any bubbles or anything either.

I'm not sure, but the top hose might have been getting warmer due to the T-stat before the fan came on, but i'm really just guessing.
More interesting. All the conditions you report are normal and indicate a properly running cooling system. I had hoped that we'd get a clue as to what is going on by testing with the AC and heat off. I think we can say there is no radiator, thermostat, water pump or head gasket issue. At least not as tested.

That points to something in the electrical system causing your problem when the AC or Heat is on. Let's call that the HVAC system for simplicity. So where's the fault? I doubt that it is in the cabin HVAC controls. I think it's more probably under the hood, and something interfering with the function of the cooling fan, thermostat or water pump.

As someone suggested earlier, everything points at the water pump. We know your fan works. The thermostat doesn't interface with the HVAC system on your car. Something is causing your pump to stop functioning and all your symptoms are classic pump failure.
But why only with the HVAC on? I'm going to guess a bad electrical ground or bad relay or a short circuit. When you turn on the HVAC there is a current overload due to an electrical fault, it backfeeds looking to go home to the battery, and it interferes with the pump control circuitry.

I'm afraid you are going to have to find someone with good diagnostic skills, a V-O-M, and a good set of wiring diagrams. A fool is going to tell you that your pump is bad because it stops working, but the cause is outside the pump. A good tech will find the cause. Doing so is not going to be cheap but at least you won't pay for things you don't need. At my shop we'd go online and check for BMW TSBs, pattern failures, search I-ATN and Identifix, download diagrams, pour a cup of coffee and go to work. In that order.

One other thing. The very first test we'd do is hook up a scanner to your car and see if we can command the water pump on while the HVAC is running. If not, we've narrowed the search way down. We'd know that circuit is faulty. Then we'd pull the relay and send a 12v shot direct to the pump and see if we had action, if so the problem is between the battery and the relay. That leaves a lot of real estate to cover, including the ECU 'cuz that's where the decision is made to turn on the pump. And that decision is based on information sent to the ECU from different sources so they have to be checked too.
It isn't rocket science, but it has to be done methodically.

All of the above is based on my wild ass educated guess that it's pump failure. If it turns out that your frimmis regurgitator has lost it's smoke then I'm going to look awfully stupid.

Last edited by DSXMachina; 11-23-2011 at 06:33 PM.
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  #9  
Old 11-25-2011, 10:29 AM
gerrg gerrg is offline
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so all these problems (started when running the AC) started a week after taking it to the dealer for service (i think it was an oil change). when i opened the hood for the first time when it overheated, i found what looked like an o-ring pick. it was a spike bent to a 90 degree angle, and it had a handle. it was stuck above my radiator fan on the outside of the housing.

Of course i thought this was the cause of all my problems, but the more the problem happened, the less likely i thought it was. I didn't take it back to the dealer as they were almost an hour away but i did call them. I still have the pick.

I'm wondering if by chance the pick was left somewhere else in my engine, hit a fan which made it nick a wire somewhere, and then get logged above the radiator fan. I'm not really sure how likely it is though.

From what you're saying, it sounds like i should be able to drive the car the 300 miles to get home this weekend (visiting family) and be fine if i don't run the heater. I might try to jack the car up when i get home and see if i can see anything. Thoughts?
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  #10  
Old 12-13-2011, 04:17 PM
gerrg gerrg is offline
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So i took my car to the dealer today and had it diagnosed. Also, i got this done for free since they left a tool in my engine the last time i got it serviced. They told me i have two problems

Problem 1: Thermostat stuck open.
This i can see, because my check engine light is on, saying the car is always too cool, which i could totally see as an open thermostat. I'll probably go ahead and change the thermostat to see if that gets rid of the check engine light.

Problem 2: Bad water pump.
I questioned them about this, and they said there was a short that happens on the water pump. This short is caused by the extra pressure when the valve to the core is open (when i turn on my heater) which creates a larger load on the water pump. I'm not completely sure how accurate that is, but then again i'm not as familiar with how the core/valve/water pump system works as they are. What do you all think?
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  #11  
Old 12-13-2011, 07:41 PM
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CALWATERBOY CALWATERBOY is offline
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Originally Posted by DSXMachina View Post
I think we can say there is no radiator, thermostat, water pump or head gasket issue.
Would a pump not able to move capacity be a problem?
__________________________________________________ _____

Edit: Guess I shoulda read the just prior post.

Yo OP....what's involved, changing your pump, $$ and procedure?
.

Last edited by CALWATERBOY; 12-13-2011 at 07:43 PM.
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Old 12-13-2011, 07:57 PM
gerrg gerrg is offline
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the dealer said the total cost would be $1600 USD, which includes 5 hours labor, $170 for the Tstat, and $610 for the water pump.

If i were to change stuff myself, which i'm considering, the Tstat should be pretty quick and simple since it's right on top. the Water pump would be a little trickier, but still do able i think. pretty sure it's on the bottom side of the car, and i think i can use the following link for some help. just skimming around, it looks like i should be able to get Tstat and Water pump for about $600 total or so, and i've already got some BWM coolant that i've been waiting to use.

http://www.e90post.com/forums/showth...ight=waterpump

I wouldn't think opening the heater core would add any more load to the pump. maybe when you open the core, the car speeds up the water pump? i would think it would keep pumping like it normally does, but i'm probably wrong.
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Old 12-13-2011, 09:01 PM
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CALWATERBOY CALWATERBOY is offline
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the dealer said the total cost would be $1600 USD, which includes 5 hours labor, $170 for the Tstat, and $610 for the water pump.

If i were to change stuff myself, which i'm considering, the Tstat should be pretty quick and simple since it's right on top. the Water pump would be a little trickier, but still do able i think. pretty sure it's on the bottom side of the car....

I wouldn't think opening the heater core would add any more load to the pump. maybe when you open the core, the car speeds up the water pump? i would think it would keep pumping like it normally does, but i'm probably wrong.
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Old 12-14-2011, 05:01 PM
gerrg gerrg is offline
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So i've been thinking and talking to some friends. Could this possibly be caused by the solenoid/valve that is connected to the heater core? if there is a short there, then maybe that could cause the water pump to also show a short and have it shut off until power is removed from the system?

If that's the case, i could disconnect power to this valve/solenoid, start the car, turn the heater on, and see if my radiator continues to push out warm air or not. if it does, then that would lead to a bad heater core valve i would think.

Not sure how probably this is, just seeing what you guys think.
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Old 12-14-2011, 05:09 PM
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DSXMachina DSXMachina is offline
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Quote:
Originally Posted by gerrg View Post
So i've been thinking and talking to some friends. Could this possibly be caused by the solenoid/valve that is connected to the heater core? if there is a short there, then maybe that could cause the water pump to also show a short and have it shut off until power is removed from the system?

If that's the case, i could disconnect power to this valve/solenoid, start the car, turn the heater on, and see if my radiator continues to push out warm air or not. if it does, then that would lead to a bad heater core valve i would think.

Not sure how probably this is, just seeing what you guys think.
I think you have a good idea. It's worth a try! It won't neccessarily prove anything but it will be interesting to see if maybe the valve is shorted. Normally that would blow a fuse, but disconnect it and lets start there.
The thermostat probably was damaged the first time you overheated. They often stick open when the wax pellet inside overexpands and bursts the cylinder.
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Old 12-14-2011, 05:12 PM
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DSXMachina DSXMachina is offline
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Originally Posted by CALWATERBOY View Post
Would a pump not able to move capacity be a problem?
__________________________________________________ _____

Edit: Guess I shoulda read the just prior post.

Yo OP....what's involved, changing your pump, $$ and procedure?
.
Quite possible that the pump is getting insufficient amperage to move coolant properly when another device on the same circuit is defective.
I'll check the wiring diagram in the a.m. and see what's there.
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Old 12-19-2011, 12:19 PM
gerrg gerrg is offline
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So i ordered my thermostat today, and plan on changing it out when i go home for christmas vacation. I also plan on disconnecting the heater core valve (electrically) to see if that is what's causing my water pump to short out. The heater core and radiator/engine coolant lines run in parallel, correct? It doesn't put the heater core in between my water pump and radiator does it?

Also, today i was driving back from lunch and i decided to turn my AC on, and put the temperature up as high as it would go. it's a digital control and maxed out at 84F. When set to 84 there was pretty warm are coming out of the vents, but if i turned it down to 83 it started to put out colder air. Is it bad for me to run my AC at 84? didn't know if it would burn anything up and actually didn't know exactly where it was getting the heat from.

Any luck looking at those drawings by the way?
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Old 12-19-2011, 01:40 PM
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DSXMachina DSXMachina is offline
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Quote:
Originally Posted by gerrg View Post
So i ordered my thermostat today, and plan on changing it out when i go home for christmas vacation. I also plan on disconnecting the heater core valve (electrically) to see if that is what's causing my water pump to short out. The heater core and radiator/engine coolant lines run in parallel, correct? It doesn't put the heater core in between my water pump and radiator does it?

Also, today i was driving back from lunch and i decided to turn my AC on, and put the temperature up as high as it would go. it's a digital control and maxed out at 84F. When set to 84 there was pretty warm are coming out of the vents, but if i turned it down to 83 it started to put out colder air. Is it bad for me to run my AC at 84? didn't know if it would burn anything up and actually didn't know exactly where it was getting the heat from.

Any luck looking at those drawings by the way?
The saga continues. Here is what I need you to do, and be sure to follow these instructions closely.

1. This vehicle operates with an electric water pump.

2. To operate the pump, make sure the climate control is set to maximum temperature and minimum fan speed.

3. Turn the key on, engine off and press the accelerator pedal to the floor and hold for 10 seconds.

4. The electric water pump should start running and the automatic bleeding procedure will continue for approximately 12 minutes. The pump will not run continuously or at the same speed the entire time.

Let me know what happens. FYI, out of the last 27 cases similar to yours, 24 were resolved by the installation of a new water pump.

I forget, did you check for codes? BMW proprietary codes (NOT ones that begin with 'P') will memorize specific pump circuit faults and will NOT turn on the 'Check Engine' light. We'd be a lot further along if you could get a scan for BMW specific codes.
"Also, today i was driving back from lunch and i decided to turn my AC on, and put the temperature up as high as it would go. it's a digital control and maxed out at 84F. When set to 84 there was pretty warm are coming out of the vents, but if i turned it down to 83 it started to put out colder air."
When you set most any HVAC to it's max setting it goes to default override. It thinks you have an emergency and ignores contrary signals in an effort to obtain the setting you have selected. The reason for this is that you could, for instance, have a defective cabin air sensor. It could result in screwy signals going into the HVAC computer which causes it to command a cooler temperature. When you set it to Max temp the computer ignores most input and does whatever it can to max the temperature. The reason is that the engineers figure you might have a life threatening windshield icing situation or extreme cabin cold. You need heat any way they can get it. Works wonderfully, even in the summer!

Last edited by DSXMachina; 12-19-2011 at 01:47 PM.
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Old 12-19-2011, 04:34 PM
gerrg gerrg is offline
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Okay, This is what i did:

1. Parked the car after driving it for about 10 minutes.
2. Turn the car off, then hit the start button without holding the brake, so this should be in "With the key on"
3. Set the climate to heat, with max temp and min fan speed
4. hold the accelerator for about 15 seconds since i couldn't hear anything spinning
5. Listened for the water pump, which i could hear whirling periodically
6. felt the top and bottom hose, and could feel vibrations periodically, which i would assume is some kind of flow
7. remove the key and let the car sit for 30-45 minutes
8. Go out and feel the top hose for pressure, which it seemed to have some
9. loosened the expansion radiator tank cap, which removed the pressure, no fluid came out, just air
10. turn the key on, set the climate control to max temp, min fan speed and held the accelerator tot he floor for about 15 seconds
11. Listen for the water pump, which seemed to go in a cycle. it would seem to accelerator to a max speed which took about 1 second, and then stop, doing this like so: spin 1 second, stop 2 seconds, spin 1 second, stop 2 seconds, spin 1 second, stop 5 seconds... repeat
12. while this was going on, i held the top radiator hose and squeezed it. when the pump would spin, pressure would increase, and then release when the pump stopped spinning.

Also, it sounds like i should go ahead and get a water pump, shouldn't it? since i plan on replacing the Tstat as well, it might be easier to do them both at the same time. If it sounds like it's not the water pump right now then i won't bother yet. Thanks for all your help!


1. Let the car sit for about 30 minutes after i drove it across town.
2. Felt the top hose
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Old 12-19-2011, 05:37 PM
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DSXMachina DSXMachina is offline
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Not so quick. It is critical that there is NO air in the system. We have to burp it all out which is partially done by that cycle you ran through. It's OK to have air in the reservoir (above the coolant level) but there must be NONE in the system. That means none in the block, heads, radiator, pump, heater, etc.
Fill your reservoir to the proper point before continuing.
Run the cycle one more time and then drive the car. See if it still overheats. Also, when you are driving it set the heat to something moderate like 74 (keep your window down a little if you have to) and see if heat continuously comes from the heater.
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Old 12-19-2011, 05:42 PM
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DSXMachina DSXMachina is offline
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Also, it sounds like i should go ahead and get a water pump, shouldn't it? since i plan on replacing the Tstat as well, it might be easier to do them both at the same time. If it sounds like it's not the water pump right now then i won't bother yet. Thanks for all your help!
Don't get the pump yet, I'm not convinced it's bad. Probably is but so far I can't condemn it. The way it was running can be OK for the test you were doing. The pump was being controlled by the ECM and will cycle off and on. The noise you heard sounds a little excessive but I can't be sure.
Yes, it is much easier in the long run to change both the stat and the pump at the same time on your car.
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Old 12-19-2011, 06:18 PM
gerrg gerrg is offline
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Originally Posted by DSXMachina View Post
Not so quick. It is critical that there is NO air in the system. We have to burp it all out which is partially done by that cycle you ran through. It's OK to have air in the reservoir (above the coolant level) but there must be NONE in the system. That means none in the block, heads, radiator, pump, heater, etc.
Fill your reservoir to the proper point before continuing.
Run the cycle one more time and then drive the car. See if it still overheats. Also, when you are driving it set the heat to something moderate like 74 (keep your window down a little if you have to) and see if heat continuously comes from the heater.
Right now it looks like there is actually a little too much coolant in the system. There are two balls on the coolant level stick, and the bottom one should be right at the top of the cap... well the level stick is as high as it can go right now. Should i let some out... and how should i go about doing that?

Also, as far as getting air out of the system, do i use the bleed screw, which i think is just next to the cap on the radiator expansion tank? or should i just run the water pump only a couple more times by holding the accelerator for 10 seconds?
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Old 12-19-2011, 08:32 PM
gerrg gerrg is offline
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Mein Auto: 325i
So i drove my car about 10 minutes tonight with the heater off and then loosened the bleed screw a bit and some bubbles came out. I then drove back to my place and did the same thing. there were some more bubbles. The second time i did this i drove the last few minutes with the heater on, and then when i stoped i turned the car off, and then turned the key on and made sure the heater was on and set at max. Think i should keep doing this a few more times over the next day or two until no more bubbles come out?
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  #24  
Old 12-20-2011, 05:39 AM
DSXMachina's Avatar
DSXMachina DSXMachina is offline
Non compos Mentos
Location: New Hampshire
 
Join Date: Dec 2007
Posts: 10,368
Mein Auto: 335i E92 TiAg 6MT ED
Wouldn't hurt. What is going on with the heat and engine temperature? Remember, if your stat is stuck open you won't get much heat unless your temperature gauge is showing enough engine heat.
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  #25  
Old 12-20-2011, 07:09 AM
gerrg gerrg is offline
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Location: Dallas
 
Join Date: Nov 2011
Posts: 20
Mein Auto: 325i
Drove again this morning without the heat on, and then turned the engine of, set the climate control to max temp and min fan speed, and then loosened the bleed screw again. There were a few more bubbles right at the beginning (seemed like a bunch of bubbles for about half a second) and then just coolant for the next 5 seconds or so.

Last night when i turned the heat on for the last few minutes of the drive, the air was pretty warm. The air temp didn't go down, and my engine temperature light didn't come on, so i'm not sure how hot or cool the engine was, but the radiator was still blowing out warm-ish air when i got it. Seemed like it might have been cooling down though. Next time i drive it I will start with the heater on and see if it starts kicking out warm air ever.

Also, since last night my check engine light has been off. First time in about a month or so. This is the check engine light telling me my engine was tool cool all the time. I'll keep you posted. Thanks!
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