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Steve
Steve, BMW Expert
Category: BMW
Satisfied Customers: 23023
Experience:  BMW Expert
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I have a 2007 bmw x3 3.0si the expansion tank radiator

Customer Question

I have a 2007 bmw x3 3.0si the expansion tank for the radiator busted so i repaired it and replaced it it busted again so i bought a brand new one and put it back together then it blew a hose off what could be causing all this pressure?
Submitted: 1 year ago.
Category: BMW
Expert:  Steve replied 1 year ago.
Hello and welcome,
My name is ***** ***** it will be my pleasure to assist you today.
I will provide an honest answer. I trust this will be appreciated. Please remember that a low rating PUNISHES me for being honest and that I receive nothing for my time until a positive rating is clicked.
if you do in fact have high pressure, that would most likely be caused by air in the system or a blown head gasket (or other breach like a cracked head or block)
I would suggest a block test or leak down test at this time to verify if you are looking at a breach or not
Please let me know if you have further questions. Please do not forget to click a positive rating as this is the only way I receive credit for my answer, thank you. Best wishes with your vehicle.
Customer: replied 1 year ago.
Would the thermostat be a possibility? It has a small thermostat looking thing that was broken it goes in the bottom of the expansion tank
Expert:  Steve replied 1 year ago.
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that is not the main thermostat, it is the transmission cooler thermostat, and is unlikely to be the cause.
however, if it is broken, it would not hurt to replace it and see if anything changes.
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Customer: replied 1 year ago.
Where is the main thermostat located and could he main thermostat be the cause? The truck only has 70k miles driven by a grandma i hate to think it's a blown head gasket
Expert:  Steve replied 1 year ago.
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if the car was overheated then the head gasket could have blown
the main thermostat on an si model is beside the water pump:
http://blog.bavauto.com/14581/bmw-how-to-video-electric-water-pump-replacement-diy-n51-n52-n54-n55-6-cylinder/
http://www.bimmerfest.com/forums/showthread.php?t=669612
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Customer: replied 1 year ago.
The truck runs perfect no sign of water and oil mixing and the temperature gauge never went above middle just boom it blew we shut it off and had it towed could the thermostat have caused this?
Expert:  Steve replied 1 year ago.
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if the car does not overheat then the likelihood of the thermostat being the issue is slim
the water pump is a much more common failure, but again, without an overheat, then unlikely.
this vehicle has a special refill and purge procedure.
if you have not done the procedure, you probably have air in the system as I suggested originally
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Customer: replied 1 year ago.
Do you have the procedure that you can link me? And what could possibly caused the initial tank to blow?
Expert:  Steve replied 1 year ago.
I have submitted a very fair offer for this.
Customer: replied 1 year ago.
What do you mean are you done helping me?
Expert:  Steve replied 1 year ago.
I have submitted an additional services offer for you to accept to get access to the factory BMW pdf instructions for this procedure for a small and fair incremental charge. You should have the ability to accept this offer and access the instructions which you have requested
Customer: replied 1 year ago.
Anytime I've ever used this site no one's ever tried to charge me extra this is ridiculous
Expert:  Steve replied 1 year ago.
it is a new feature that the site has rolled out. you have asked for something extra beyond the scope of the original question, and I have offered it for a small and fair charge vs. the cost of a new question.
if you do not wish to invest the $5, then you can decline the offer and I can find you a link on google to a home made DIY instead of factory BMW instructions which are not free to access.
Expert:  Steve replied 1 year ago.
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the tanks just crack from age
here are links to the venting procedure: https://www.youtube.com/watch?v=pLqFS0h0eOI&spfreload=10
http://wiki.bavariantechnic.com/index.php?title=Coolant_Bleed_Procedure
As the question has been answered, please kindly CLICK ON a positive rating
Expert:  Steve replied 1 year ago.
Please do not forget to CLICK ON a positive rating
the tanks just crack from age
here are links to the venting procedure: https://www.youtube.com/watch?v=pLqFS0h0eOI&spfreload=10
http://wiki.bavariantechnic.com/index.php?title=Coolant_Bleed_Procedure
As the question has been answered, please kindly CLICK ON a positive rating.

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