Overheating / How to troubleshoot?!

[slidinthru]

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Hey guys, I am trying to troubleshoot what is wrong with my brothers 2004 z4 3.0.

The other day it started to get hot while driving home (in Vegas its like 105+ outside right now).

We replaced the thermostat and it still got hot while after awhile.

I think it might be the electric fan, since it won't turn on while trying to diagnose the issue at temp. When I click on the Ac it does 1 revolution and doesn't spin anymore.

Any ideas on how to confirm its the fan or how to troubleshoot further?

[Clearancediver]

There is a temperature sensor on the lower radiator hose to the engine….. it controls whether or not the electric fan comes on…

It is inexpensive and easy to replace. I would get OEM rather than cheap ebay replacement.

Nothing to lose by replacing as part of cooling system maintenance. Once you have done that you can cross off one potential cause if issue remains.

While you are at it… check out health/charging/charged voltage of battery/alternator to eliminate any low voltage caused issues.


Sent from my iPhone using Tapatalk

[JAS1169]

Please read: https://z4-forum.com/forum/viewtopic...e+fan#p1693542

Afterwards, google BMW z4, E85 fan green wire

You'll find more posting and as I recall some have pictures of the green wire that turns into dust.

[BimmerBreaker]

This is almost guaranteed to be a faulty fan or fan wiring.

Use INPA to manually trigger the fan to run. If it doesn't run then check continuity between the small wire at the fan wiring harness and the DME X60004 pin 4. It is very common for these to deteriorate over time, this is true for all M54 equipped BMW's (except Z3's since they used a different type of fan). If the fan itself was failed, it wouldn't be likely to run that single pulse when the A/C is on - that can happen though when there is a poor connection for that smaller wire.

When I run into this issue - and it is fairly common - my first step is to test the fan in a different model. A lot of the BMW's from the same era use the same fan plug and wiring, so you can test it on other models if you don't have another Z4 or E46 available. If the fan works in a different car, then I run a complete new wire from the DME X60004 pin 4 to the small wire on the fan.


Also, a faulty lower temp sensor will not cause overheating. The fan will run at max speed if there is no input or an erroneous value from the lower sensor. On that note, if you don't have INPA (and you should get it if you plan on maintaining a BMW, it isn't expensive, the software is free and the cables <$20) you can unplug the lower radiator sensor and that will force the fan to run at full speed.
It also won't be a voltage issue. The engine and the engine auxiliary components like the fan are the last thing the car will disable in a low voltage situation. It will start to misfire before it will just disable the fan due to a voltage issue. There is a "secret cluster test" you can do that shows a voltage readout though if you wish to double check this for any reason.

[slidinthru]

UPDATE!


While playing with the car trying to figure it out, I noticed the AC compressor smoked a little while the ac was clicked on.


I feel like I remember someone saying that if the AC isnt working properly the rad fan won't either.


Any ideas on that?

[BimmerBreaker]

UPDATE!


While playing with the car trying to figure it out, I noticed the AC compressor smoked a little while the ac was clicked on.


I feel like I remember someone saying that if the AC isnt working properly the rad fan won't either.


Any ideas on that?

The fan is controlled by the DME and will operate regardless of the A/C working or not. When the DME detects the fan is not working, it will not allow the A/C to work but the fan will work even if the A/C is not working.

Use INPA to manually trigger the fan to test it's operation and diagnose it from there. I gave you a rather thorough process to diagnose any potential fault related to the fan in my previous post. Even without INPA you can test the fan, as I described in my previous post