heat on, cold air when car stops in traffic

[sproule905]

Has anyone encountered something like this? First, it takes my car an alarming rate to get up to temp for the heat to sift through the vents. Secondly, when i do have heat it slowly turns colder once I am stopped at an intersection. Lately, its been moderate, but still not where it should be. I know my older 318i had a flap to let air cycle through the fan, but could this flap on my 328is be stuck open? is there even one?

I hope its not my thermostat because my temp coolant is bang on, plus i recently changed it!

any suggestions!!?

thanks,

[jeffrie]

Air in the system

[craigIS]

this happened to me a couple years ago. i ended up having to replace the heating core or something like that. it got worse slowly.

[ScotcH]

Possible causes are air in the system, or stuck open thermostat. Those are easy to fix, so start with that. If you bleed it properly after replacing the thermostat, then you might have bigger isssues (heater valve, heater core, head gasket, etc).

[sproule905]

air in the system.. do you mean in the Rad?

[sproule905]

if not, what is the best " how to/do it yourself" way to get that effn sh!t out!!??

[LondonWraith]

thats what the bleed screw on top of your rad is for

[BmW1819]

there is heat taps on your car and when your car is sitting your water pump is not pump as much so when u start moving u water pump pushes more coolant through so u get heat your heater tap is starting to clog have u put a stop leak in it in the past??

[ScotcH]

Originally Posted by sproule905

air in the system.. do you mean in the Rad?

Yes, the rad. Replace you thermostat, and fill and bleed it properly. There are many in depth DIYs out there, but here is the general idea on how to fill properly:

1. raise front passanger side of car so the rad cap is the highest point in the cooling system
2. open the bleed screw and rad cap
3. fill with BMW coolant mixed properly until you can fill no more ... this will take a while, and you'll have to go really slow at the end. You're done when it reaches the top of the filler, and will not go down anymore.
4. close the rad cap
5. close the bleeder

Put the heat on full blast and warm up the car.

You might have a bit too much coolant in there with this procedure, but you won't have any air. After the car is good and warm, let it cool again (like overnight) and check the level of the coolant. if it's around the cold mark, you're good ... a bit more is OK, belowe the line, fill it up again.

[sproule905]

ScotchH - thanks man! i recently changed the coolant and about amonth after the Low Coolant display came on! i'll get on that this weekend with the bleed screw on the rad!

THANKS!!!

[sproule905]

oh and thank you everyone else.. i'll update shortly.. or whenever i'm off work.

[jeffrie]

I do it a little different then Scotch as I'v still had air trapped a few times using the bleeder screw, plus is often messey as air has to go backwards through the system which overflows the bottle as traspped air makes it's way to the bottle or bleeder screw.

What has worked 100% of the time was revease fill it, bottom first so air ends up coming out of the bottle instead.
Easy to do, just take upper rad hose off, hold it up high and fill from their till it begins to overflow out of bottle and rad were the hose belongs, then re attach it.
If too slow and you spill too much attaching the hose, top off the bottle to proper cold mark.

Start it up with heater on full with rad cap off (bleeder screw closed) till up to tempurature level should hardly change as most of the air should already all be out. Be best to check if it needs a top off again after a day or so but I never have had too sofar.

[sproule905]

thanks Jeffrie.. rule of thumb is to always have the rad cap off to let the remaining air escape! i'll keep you posted over the weekend!

[Shuks]

I have the same problem, how did it go Sproule?

[Soul_Rebel]

Also, this gets overlooked everytime, make sure the center vent is switched to the red side and not the blue...