Cannot get the air out of the cooling system! Weird
 

Hi everyone, very important thing here!
Just recently noticed that my temp went to 107-108C, no overheating, but my tranny was acting up while driving in traffic!!! Guess what???
Inpa says 98-102C tranny temp!!
So I checked my radiator and it was only half hot, lower side completely cold!!!
Ok, air in the system? Tried TIS procedure and it didn't do anything. Yes I have new aux water pump.
Installed new tstat and still same thing, water pump is almost new. Wheep hole was fixed too! No leaks anywhere!
Removed tstat and all is good- tranny temp is good never overheats.
Once I put it back same thing is back!
So... Why it's so important?? Bc I just saw my friends car 87k recently he replaced his tranny and its almost same thing!! His car is almost 110C.
His engine is leaking everywhere.
Well, and I saw another 745 160mls with normal hot radiator everywhere and his temp would never go any higher than 102-105, original tranny and engine valve cover gaskets no leaks, only alt bracket seal.
This air in the system will destroy your engine and tranny pretty quick!
So bmw self bleeding system is not working sometimes??? So?? I'm trying to understand if anyone had this issue??
I mean you might have the same problem without even knowing about it.
Simply check if your radiator is hot everywhere after you drive with normal 105 temp.
Needless to mention that it will kill your alternator bc it's water cooled and getting coolant from the tranny cooling heat exchanger.
Pretty much 90% engine and tranny issues described here is all related to this problem.
Thanks.

there are two place to check before tstat and after. Right?

Yep, lower hose is cold at 105C barely hot. It means tstat is not opened. Aux fan will kick in at 105C but isn't helping bc radiator is half hot anyways. No overheating problems no massages or errorS except for overheating tranny in traffic. All is good on the hwy!
745 with no air in the system will not get to 105 when idling (will take forever) also noticed that aux fan kicks in at 100-101C!
The worst problem it's not easy to detect if your tranny is doing ok with overheating. Just check if your tranny temp is no higher than 86-88C after driving in traffic. It does suck bc of no errors whatsoever
Any ideas why self bleeding system is not working in 2 cara already? Also found 3-4 cases online with no help!

how does work self bleeding system?

Simple TIS instructions:
1) Turn on heater (aux watee pump must be in working order) on high and blower on low, fill up the tank slowly.
2) start the engine and wait 1-2 mins
3) close the cap and run the engine normally
4) when cold check the coolant level, top it off if needed.

It's definitely explains my tranny weird behavior while in traffic or going uphill.
If your aux fan is not spinning at 100C at low speed and only kicks in when its 105 C (dme opens up tstat a little) you've got air!

there is half people do not have aux water in working order. It mean self bleeding not working? Mine is out too. I think there is more then that

Mine was bad. I replaced it but funny thing it fixed my heater;) who gives a fk about heater if system has air pocket??
It's kinda sucks bc heater will blow hot if aux water pump is good, in other words you won't see any symptoms like in other cars without aux pump.
If cooling system is air free you should be getting hot air even without any aux water pump.

How does the coolant effect the transmission?

where is located?

Hmmm that's a good one;)
Tranny oil Cooler or heat exchanger connected to lower radiator part along with tranny thermostat. It's very important to have no air pockets bc it will affect tranny cooling and alternator!

Thanks for the info. Let us know when you resolve your problem.

I'm already pulling my hair out ;)
Was thinking if smbdy had this issue resolved somehow. It's very important issue. So I recommend to check it for everyone.
Last things left:
Tranny tstat (though I doubt it's related)
Heater core bypass

In any case smth happens to self bleeding bmw design and air stays in there. Too bad they removed any bleeding screws.

I think I finally got it out using old school methods.
But what I realized is:
Even if aux water pump is dead, heater still has to blow hot, otherwise there is an air lock.
With aging some hoses or connections might suck some air in.
Now I'm thinking how to retrofit original 105C thermostat to smth with 96C. It will help your engine to survive that stupid 105C heat and all rubber seals will stay flexible.
Any ideas?? I'm thinking of using M54 tstat somehow.
For some reason bmw made it on purpose so engines won't last more than 100miles. Remember first V8 M60? It was 85-95C and no issues with valve stems.

Well so far everything is good. System is air free!!!
Make sure your heater blows hot without aux pump connected. If its not than you've got air. Very serious problem which will kill your tranny, engine very quick! Why it gets air pockets?? Simple: aging plus some plug and play connections are not perfect.
Worst thing you cannot tell if you have air or not bc aux waterpump always keeps your heater hot even with air. Now my car has desert hot heater without any aux water pump( it's been dead). Coolant temp never gets warmer than 105 even with old fan clutch.;)))

What did you do to get air out of the system?

First you need to make sure you have it;)
I disconnected heater core while engine was running and put it back