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E85 / E86 Z4 (2003-2008)
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  #1  
Old 08-29-2012, 12:40 PM
Droptop85 Droptop85 is offline
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E85 z4 transmission thermostat

So my expansion tank recently started leaking coolant. Water poured out of the bottom large o-ring. Tank is fine no cracks fortunately as its a 100 dollar part. But! While removing the tank I noticed the thermostat to the transmission cooler was also broken. Is this part really necessary? I pulled the stat out and was thinking about running it without it. I can't see this hurting the transmission or any other parts? Thoughts? Only thing I can think of is the trans will take a tad longer for oil temps to warm up. But it's not like I live in cold weather here. I really don't see a need for this part.
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  #2  
Old 08-29-2012, 10:52 PM
Droptop85 Droptop85 is offline
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Nobody?
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  #3  
Old 08-30-2012, 03:14 AM
Mikey48 Mikey48 is offline
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I would think if the BMW Engineers put this part on the car their must be a need for this part. I would put a new one on.
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  #4  
Old 08-30-2012, 02:56 PM
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shipkiller shipkiller is offline
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In my experience, I feel that Mikey48 is dead on the money.

The OEM's would not put something on a car unless it was needed. They could keep it off the car and charge the same price and boost the profit margins.
You also don't know what the ECU does with that data.....

Are you sure its a transmission temperature sensor? I cannot find anything in any documentation that talks about a sensor for that.
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  #5  
Old 08-30-2012, 03:01 PM
Droptop85 Droptop85 is offline
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No it's the thermostat for the transmission cooler. It bolts on the radiator on the bottom driver side. It's works similar to a air/water intercooler
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  #6  
Old 08-30-2012, 03:08 PM
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shipkiller shipkiller is offline
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I sorta figure this is for the automatic transmission.
Are you talking about no. 4 in the diagram?

http://www.realoem.com/bmw/showparts...41&hg=17&fg=05
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How does something immoral, when done privately, become moral when it is done collectively?
Furthermore, does legality establish morality?
Slavery was legal; apartheid was legal; Stalinist, Nazi, and Maoist purges were legal. Clearly, the fact of legality does not justify these crimes. Legality, alone, cannot be the talisman of morel people. - Walter E. Williams
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  #7  
Old 08-30-2012, 03:11 PM
Droptop85 Droptop85 is offline
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Yes sir that's her alright.
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  #8  
Old 08-30-2012, 03:19 PM
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shipkiller shipkiller is offline
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Learned something new today...

From the WDS (BMW Electrical Manual):

The transmission oil sump temperature is sensed by a temperature-dependent resistor which is soldered in the transmission wiring harness. Among other things, engagement of the torque converter lockup clutch is controlled dependent on the transmission oil temperature.


The way I read this is that the transmission control module, will very the amount of torque need based on fluid temperature. Now knowing that the automatic transmissions that BMW uses don't last like good old American autos, I would definitely put this back in. These transmissions are (normally) not rebuild-able and if it goes, you replace the entire unit... I also replace the transmission fluid every 30K miles... (http://www.shipkiller.com/Autoxmission_fluid.html)
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How does something immoral, when done privately, become moral when it is done collectively?
Furthermore, does legality establish morality?
Slavery was legal; apartheid was legal; Stalinist, Nazi, and Maoist purges were legal. Clearly, the fact of legality does not justify these crimes. Legality, alone, cannot be the talisman of morel people. - Walter E. Williams
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  #9  
Old 08-30-2012, 03:24 PM
Droptop85 Droptop85 is offline
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That was very helpful. Thank you. I'll definitely be replacing that part.
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  #10  
Old 08-30-2012, 03:37 PM
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shipkiller shipkiller is offline
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Since you replaced the tank O-ring, I would be willing to bet the next thing to start to leak will be the coolant temp sensor, or more specifically the O-ring, then the O-rings in both hoses....

When I developed a leak in the wife's Roadsters cooling system, I just went ahead and replaced both hoses and the temp sensor. Now I don't have to worry about it for another 40-60K miles.....
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How does something immoral, when done privately, become moral when it is done collectively?
Furthermore, does legality establish morality?
Slavery was legal; apartheid was legal; Stalinist, Nazi, and Maoist purges were legal. Clearly, the fact of legality does not justify these crimes. Legality, alone, cannot be the talisman of morel people. - Walter E. Williams
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  #11  
Old 08-30-2012, 03:44 PM
Droptop85 Droptop85 is offline
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I'm going to replace all the o rings since its all off at the moment. The thing is BMW won't sell me just the o rings. I have to buy the whole expansion tank for a 37 cent part that I need. And all the hoses and temp sensor. And all I need are the o rings!!!! There goes another 300 bucks
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  #12  
Old 08-30-2012, 03:51 PM
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shipkiller shipkiller is offline
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Yep,,

You can source the O-rings on the internet. Just remember these are METRIC O-rings...

If the expansion tank is the original one, then it could be on borrowed time...

Use your BMW CCA discount (15%) or price out the parts at Tischer......
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How does something immoral, when done privately, become moral when it is done collectively?
Furthermore, does legality establish morality?
Slavery was legal; apartheid was legal; Stalinist, Nazi, and Maoist purges were legal. Clearly, the fact of legality does not justify these crimes. Legality, alone, cannot be the talisman of morel people. - Walter E. Williams
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  #13  
Old 08-30-2012, 03:54 PM
Droptop85 Droptop85 is offline
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The expansion tanks looks like it has been replaced before. Which is odd. But your right, might as well just replaced it for peace of mind.
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  #14  
Old 09-18-2012, 01:05 AM
Droptop85 Droptop85 is offline
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Anyone know where I can find the expansion tank o-rings? I'm having no luck so far.
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  #15  
Old 09-18-2012, 01:28 AM
Droptop85 Droptop85 is offline
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Nevermind that precious post. I just found the crack in the expansion tank.
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