Strange issue: Coolant oil thermostat dropped off
 

Hi guys,

This is my first post. Thanks for reading.

I have a 2004 BMW X5 3.0I which has some problem of radiator lower hose. I replaced the lower hose and coolant temp sensor one week ago. Then drove 2 days without any leaking or engine overheating issue.

Last Wednesday, just after I stopped my car in a parking lot, I saw the coolant all flew out and it's very hot. I towed my car back to home, battery also dead. After checking my lower hose, I found it's very dry and has no problem at all. Then I saw my trans oil cooler loose.

I pulled it out and an oil thermostat dropped as well, I couldn't find a place to put the oil thermostat back. After search a while I think the thermostat is under the expansion tank which is completely dry. The root cause is when I reinstall the radiator fan shroud I hit the oil cooler clip. But I don't know that is so important and just ignore that.

Now put the oil cooler back and tight it with the clip. replaced the battery. Car looks good without any coolant leak and engine overheating. But I got a piece of broken oil thermostat and don't know why it will drop.

Could you guys give me some help about this? any hits or idea?

I actually don't wanna to replace my expansion tank unless I have no choice.

Thanks,
-Bryan

welcome to the forum...

so, your coolant issues are resolved and the only issue you are having is the oil thermostat not placed correctly?

is this the item you are referring to? the oil pressure switch?

do you have a pic of your "extra" part?

Thanks, man. I think the coolant issue is resolved since I drove several times without any warning and leaking.

I do have the parts, but don't have the real picture now. And I search one picture from Internet. Please help to take a look.

-Bryan

Do you guys have any idea about this issue? Need I put it back to the car or just leave it there? Looks like missing oil thermostat is not a big issue but MPG will be worse, right?

Thanks,
-Bryan

FYI-there are not parts on an engine that are not there for a reason. Failures of some cause big problems failures of other cause small problems.

The following should be helpful:https://www.youtube.com/watch?v=UwhfkQRN2jQ

naaahhh... since i was a kid, i would take things apart, and then, maybe, i put them together... almost on every occasion i would end up with a spare part or two... and the thing still worked... :nanana:

on the other hand, seriously, i would say that if something was there, it was there for a reason...

OK, thanks. I'm going to purchase a set of expansion tank to replace all of them.

-Bryan