Cold air in vents

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Adammcf
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Sun Apr 02, 2006 9:50 pm

Since rebuilding the engine Ive bled it as much as I can and no more air seems to be coming out. However the top vents on the dash only put out hot air when the heater is turned right up.
The window vents and footwell vents work as normal and put out warm air at around the half way setting when the top vents will be cold.

How is this as I thought the air was heated up in the same place and just blown out to all the vents.
Adammcf
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Sun Apr 02, 2006 9:51 pm

If it is an air lock whats the best way to get it out.
Bob_S
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Mon Apr 03, 2006 6:54 pm

this annoys the hell out of me but it's how BM designed it to be! I cant remember where I read it but am sure it's supposed to be like this mate
Bollocks to this 24v scrap!
reddevil
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Mon Apr 03, 2006 8:35 pm

Mine is like that Adam, exactly the same, it's either full on or freezing cold?, thought that's just the way things were too be honest.

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bigun
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Mon Apr 03, 2006 8:47 pm

i would carry on with bleeding it bmw's are reknown for it wouldnt hurt to check the thermostat (put it cold in a clear cup yhen add hot water you should see it open) also see it you can run some cleaning agent through the rad,heater matrix,engine but since your capable of re-building your engine i dont want to sound patronising jus tryin to help i just re-built my sport engine i ran the steam cleaner through the matrix and rad before reinstalling i had no problems with bleeding oh i also helped by blowing down my header tank :thumb:
Adammcf
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Mon Apr 03, 2006 10:32 pm

bigun wrote:i also helped by blowing down my header tank :thumb:
That must have been a sight! lol

I'll try bleeding it a little more after I take it for another run tomorrow night and see if it makes any difference. Its a bit of a crappy design if its supposed to be like this!
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KDS
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Tue Apr 04, 2006 2:46 am

Mine's the same, too. I just close the center vents and direct all the heat to the floor and defroster.
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Brianmoooore
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Tue Apr 04, 2006 9:01 am

Face vents put out cool air untill the heat knob is up to half way or so.
This is how BMW designed it, and it is an excellant piece of design.
You don't want red hot air blowing straight in your face, just because the screen is misting a bit or the cabin is a bit cool.
Air lock in the heater circuit tends to be either there or not, nothing in between. If heater output is poor, check the two hoses on the bulkhead are the right way around.
Adammcf
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Tue Apr 04, 2006 10:04 am

The hoses are on correctly and the air coming out of the other vents is hot so it looks like everything is as it should be.
Cheers.
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KDS
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Tue Apr 04, 2006 4:06 pm

Brianmoooore wrote: This is how BMW designed it, and it is an excellant piece of design.

Cool! One less thing to fix.
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Tue Apr 04, 2006 4:31 pm

I'd also suggest raising the front of the car and also remove the header tank and keep it as high as poss when filling it up.

Massage all the pipes, including the ones by the bulkhead.

I also always fill the rad through the main top hose, then secure and I find a combination of running, massaging the pipes and opening the bleed valve on the stat every few mins helps.

I've only just redone mine after I swappedhead gaskets so this is all so very fresh in my mind!

Good luck, HTH, Mark.
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DazzyA
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Tue Apr 04, 2006 5:27 pm

I had air block which I couldn't find, turned out to be the pipe at the bulkhead, quick pull off :eek: and all ok.
Thank's to Brian Moore of course.
Pass me the spanner
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