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View Full Version : Coolant drain and refill


legend700
07-09-2012, 07:32 AM
Bentley's says to "Set seat heat control to maximum" before refilling radiator. Why would that step be necessary?

txag_530i
07-09-2012, 12:27 PM
They want to get the coolant replaced in the heater core. I don't think that it would matter whether or not you turned the heat to maximum before or after filling the radiator. Of course, this is a BMW, so who knows?

HPIA4v2
07-09-2012, 01:48 PM
They want to get the coolant replaced in the heater core. I don't think that it would matter whether or not you turned the heat to maximum before or after filling the radiator. Of course, this is a BMW, so who knows?
The idea has been tossed around from the ole-day, when you drain coolant from radiator, engine, exp-tank etc; there is a chance some of the coolant also drained out of heater code (gravity). once you put everything together and filling the coolant back, air may be trap in the heater core, this is one way (maybe the only cost effective way) to purge that air pocket.

legend700
07-09-2012, 05:30 PM
Bentley's is talking about S e a t heat control. That's what I find puzzling. Heated seats are on option and also electric, as far as I know. In full it says:
Before refilling radiator:
Switch ignition on. (Do not start engine)
Set temperature controls to full warm.
Set blower control to low.
Set seat heat control to maximum.

borderchris
07-09-2012, 05:49 PM
The car's heating valves open fully when the seat heat is on; you're not getting full extension of the switch-valve without them on.

legend700
07-09-2012, 05:53 PM
The car's heating valves open fully when the seat heat is on; you're not getting full extension of the switch-valve without them on.
Veery interesting! Thank you.

TRS550
07-09-2012, 07:43 PM
My vote is its a misprint.

The seat heaters are purely an electric heating element. Their function has squat to do with the coolant/heating system.

Don't believe it???

Go out, turn on your ignition and then turn on your seat heater. Heats up just fine with the engine off and the coolant at ambient temp.

legend700
07-10-2012, 07:34 AM
ISTA/D is no help here either since it employs a special vacuum filling unit to add coolant. But it specifies to "Switch on low-beam headlight." during the required venting procedure after filling.:dunno:

borderchris
07-10-2012, 08:56 AM
My vote is its a misprint.

The seat heaters are purely an electric heating element. Their function has squat to do with the coolant/heating system.

Don't believe it???

Go out, turn on your ignition and then turn on your seat heater. Heats up just fine with the engine off and the coolant at ambient temp.

You're missing the point; the tail doesn't wag the dog. For quicker max heating, you'll need the seat heat on- it sends a signal to the exchanger. Assuming that your heat is set to max or defrost with heat, turining on a seat heater will allow the exchanger to be wide open immediately for quick warm-up.

During a coolant exchange, this is done to facilitate a quicker exchange of fluid. It's not a misprint; at least according to a 25 year Level 1 at BMW of Encinitas!

HPIA4v2
07-10-2012, 09:08 AM
You're missing the point; the tail doesn't wag the dog. For quicker max heating, you'll need the seat heat on- it sends a signal to the exchanger. Assuming that your heat is set to max or defrost with heat, turining on a seat heater will allow the exchanger to be wide open immediately for quick warm-up.

During a coolant exchange, this is done to facilitate a quicker exchange of fluid. It's not a misprint; at least according to a 25 year Level 1 at BMW of Encinitas!

I guess this is only true for car with cold-package (heated seat), NO?

IMHO, I don't have the full rebuttal but on my car(with full cold-package), regardless the heated seat on/off when I crank the heater vent to max, the heater core is opening up and allowing hot coolant in cause I can feel the toasty heat coming from the vent so I doubt there is connection between heated seat and heater core.

GeorgeT
07-10-2012, 09:09 AM
I believe that the radio must be tuned to 101.1 FM and the right rear passenger seat belt fastened as well.

boramkiv
07-10-2012, 01:29 PM
The car's heating valves open fully when the seat heat is on; you're not getting full extension of the switch-valve without them on.

Is this one of others, or is this the only way to get the valves fully open? I mean :yikes:!
Just thinking of this baffles me. I've worked on vehicles almost all my life and always thought that the seat heaters are just elements and thats it, but again wow! I did replace some hoses earlier this year and refilled normally. I depressed the throttle for 12 seconds and on cue it started running the pump to vent the system, so this is indeed very interesting.

TRS550
07-10-2012, 04:09 PM
You're missing the point; the tail doesn't wag the dog. For quicker max heating, you'll need the seat heat on- it sends a signal to the exchanger. Assuming that your heat is set to max or defrost with heat, turining on a seat heater will allow the exchanger to be wide open immediately for quick warm-up.

During a coolant exchange, this is done to facilitate a quicker exchange of fluid. It's not a misprint; at least according to a 25 year Level 1 at BMW of Encinitas!

If this is indeed true, then it's example number 4,672 of BMW's being overly complex. :dunno: