[Gecko123]

2011 328 e90

If I drain the coolant from the bottom of the radiator plug, roughly what percentage of coolant is removed?

I know there is an extra hose I can disconnect to allow more fluid to drain but don’t want to bother as I’m afraid I might damage something and too lazy doing it that way. I rather drain what I can from the drain plug and increase the coolant “flush” intervals.

Also, is it okay to run the water pump a bit to help remove any remaining amount. I would only run it for 1-2 mins as running it any longer may damage the pump.

[Efthreeoh]

We just went over this with George.

To drain the radiator you have to remove the engine under cover and the radiator under cover, which is most of the work. Then open the bller screw a few turns and open the reservoir cap. Then open either just the one drain plug or if the radiator has two, both drain plugs. The "extra" work to drain the block is remove the U-shaped hose between the WP and T-stat. The hose is connected by regular hose clamps. The just squeeze the feed hose going to the engine block or go top side and close the two caps and squeeze the upper radiator hose a few times. It's an extra 5 minutes of work. Or you can be lazy and increase the number of coolant change intervals and actually do more work.

Or get the fitting from Motive that lets you load the cooling system with air pressure and push any residual coolant out of the system.

Your choice.

[MightyMouseTech]

Easiest way is to remove the small coolant line than runs from the upper rad hose to the coolant reservoir at the reservoir end. Put that end into a bucket. Start the bleed procedure and keep topping up the coolant as it cycles. Keep going till you have run a couple of gallons through. Reconnect the line and done.

[gjm120]

Originally Posted by Gecko123

2011 328 e90

If I drain the coolant from the bottom of the radiator plug, roughly what percentage of coolant is removed?

I know there is an extra hose I can disconnect to allow more fluid to drain but don’t want to bother as I’m afraid I might damage something and too lazy doing it that way. I rather drain what I can from the drain plug and increase the coolant “flush” intervals.

Also, is it okay to run the water pump a bit to help remove any remaining amount. I would only run it for 1-2 mins as running it any longer may damage the pump.

I get about 1.5 gallons just by using the drain plug and doing a little massaging of the hoses and blowing into the reservoir (I know - sounds a little weird).

Since the system is ~ 2.0 gals, this is a decent percentage. I do this every 2 years so I think my coolant is pretty fresh. As Efethreeo noted, getting the splash shields off is most of the work.

[gjm120]

Originally Posted by MightyMouseTech

Easiest way is to remove the small coolant line than runs from the upper rad hose to the coolant reservoir at the reservoir end. Put that end into a bucket. Start the bleed procedure and keep topping up the coolant as it cycles. Keep going till you have run a couple of gallons through. Reconnect the line and done.

This sounds like the best idea I've heard. Minimal mess and no splash shield removal.

I assume you have to run the 50/50 mix thru so you're tossing out about 1/2 gallon of antifreeze?

Also assume the car needs to be brought to temperature where the thermostat opens up - right?

[Gecko123]

Originally Posted by gjm120

I get about 1.5 gallons just by using the drain plug and doing a little massaging of the hoses and blowing into the reservoir (I know - sounds a little weird).

Since the system is ~ 2.0 gals, this is a decent percentage. I do this every 2 years so I think my coolant is pretty fresh. As Efethreeo noted, getting the splash shields off is most of the work.

Good. That is a decent amount. 75%.

I will just do your method.

[MightyMouseTech]

Originally Posted by gjm120

This sounds like the best idea I've heard. Minimal mess and no splash shield removal.

I assume you have to run the 50/50 mix thru so you're tossing out about 1/2 gallon of antifreeze?

Also assume the car needs to be brought to temperature where the thermostat opens up - right?

Yup. Just dump in premixed. Put heater on full heat, fan speed 1. Remove the intake snorkel to allow more movement for the line. You will also need to disconnect the rad fan electrical connector. Will make sense when you go to do it. Can do it warm or cold. Normally mix one jug of concentrate with water, which is 8 L total.

Super easy, and no mess.

[gjm120]

Originally Posted by MightyMouseTech

Yup. Just dump in premixed. Put heater on full heat, fan speed 1. Remove the intake snorkel to allow more movement for the line. You will also need to disconnect the rad fan electrical connector. Will make sense when you go to do it. Can do it warm or cold. Normally mix one jug of concentrate with water, which is 8 L total.

Super easy, and no mess.

Thanks.

For the price of a gallon of coolant you get a near complete flush with so much less work and mess. This sounds great!

[gbalthrop]

Draining/Flushing Coolant was simple with Old-type mechanical thermostat between Cylinder Head(s) and Radiator. Just unbolt the Thermostat housing and remove the T-stat.

I think I understand what "MMTech" is saying, and it would work GREAT if what's in the Radiator gets pumped out, but my Old-school Analog mind has a "hang-up" with the "Remote" Thermostat that is at the Low-point in the Coolant Flow. As I understand/misunderstand the system, UNLESS the thermostat opens, OR you drain the radiator, you can run the Coolant Pump all you want, and you have NOT expelled ANY of the OLD COOLANT in the Radiator. Does the "Bleed Procedure" ALSO open/ Activate the KFK/ Thermostat? What am I missing? I presume you are talking about topping up the Coolant Reservoir which is connected to the Thermostat Housing?

BOTH TIS & Bentley provide the SAME procedure for DRAINING COOLANT:
1) Open Radiator Drain Plug;
2) Remove "Lower" Radiator Hose (actually more "Right-Middle" Radiator Hose ;-) from Thermostat Housing;

TIS/Bentley IMPLY that ALL the coolant will drain by doing those two things, with NO discussion of HOW/IF the coolant from the Block/Head drains back through the Thermostat, or if so, HOW LONG it takes to do so. Since I have never investigated the Thermostat plumbing, or dissected a KFK/Thermostat, I wonder if my assumption that the KFK remains completely closed until a temp in the range of ~ 170F to ~180F is reached is correct. I also wonder if there is some small bypass of the thermostat "Diaphragm/ Valve" similar to a "Jiggle Pin" in an old mechanical thermostat.

Since the "Lower" Radiator hose is nearly halfway UP the Right Radiator Tank, disconnecting that hose from the Thermostat housing at least drains Coolant standing in the hose. But WHAT ABOUT the Coolant in the Block/Head. As "F30" has stated (Thanks ;-) disconnecting the "U-hose" clamped to Thermostat, will drain any coolant NOT "passing through or by-passing" the Thermostat when Lower Radiator Hose is disconnected from T-stat.

So what I was really trying to learn in my thread on Draining Coolant from Block (linked below) is:
1) Will Coolant drain from block through/past Thermostat diaphragm if one simply disconnects the Lower Radiator Hose as described in TIS/ Bentley "Step 2"?
2) If NOT, would it hurt to "Activate" the thermostat using INPA F6 Activations to open the thermostat for ~ 30 seconds? Can that be done? INPA Conditions for Activation contain no indication or Warning against doing that. One is simply heating the wax in the bulb as I understand it, and I can't see any reason that would be like running an electric water heating element with water level below heating element (which WILL burn out element ;-).

I WAS/AM looking for actual procedures performed by others that have worked, and/or for explanations of HOW the Thermostat works or is configured which support the suggested procedure. If anyone has practical experience with the Thermostat or draining the system that indicate my concepts expressed above are INCORRECT, please enlighten me.

Other thread:
https://www.e90post.com/forums/showthread.php?t=1696311

Thanks,
George

[gbalthrop]

Just to get everyone on same page about Coolant System, I attach Flow Diagram.
This is from BMW Training Manual, N52 Engine.

George

[Gecko123]

I still believe the best compromise is drain from radiator which removes about 75% and fill. Since it’s a small drain hole and pointing directly downward it’s easy to control any splatter.

Saw a video where the additional step is removing one of hose and created a big mess. And based o the video not much came out relative to the amount that comes out from the radiator. So no thanks

[Efthreeoh]

Originally Posted by gbalthrop

Just to get everyone on same page about Coolant System, I attach Flow Diagram.
This is from BMW Training Manual, N52 Engine.

George

The diagram shows the WP pushing the coolant into the engine block via the hose that connects to the engine block underneath the exhaust manifold. This is why I think disconnecting the U-hose between the WP and T-stat helps easily drain the block since the hose from the block to the water pump impeller housing drains out the impeller housing at the U-hose, thus by passing the T-stat.

[gbalthrop]

Originally Posted by Efthreeoh

... I think disconnecting the U-hose between the WP and T-stat helps easily drain the block since the hose from the block to the water pump impeller housing drains out the impeller housing at the U-hose, thus by passing the T-stat.

I totally agree with your interpretation of the Flow Diagram. If I understand you correctly, you disconnect the U-Hose from the Thermostat, which would be on TOP of #3 in the Diagram. TIS & Bentley talk about disconnecting the "Quick-Disconnect" fitting at the LEFT of #3/Thermostat where the Lower Radiator Hose connects.

On my 328xi (any X-drive has more junk in the way of the Coolant Pump & Thermostat), it would be a LOT easier to disconnect that "Quick-Disconnect" fitting on the FRONT of the Thermostat. I would expect coolant to flow "Backwards" through the pump impeller just fine, and your description appears to confirm that.

My questions are still:
1) Does the Thermostat open when Bleed Procedure is run, and if NOT, how does coolant get out of Radiator (which is probably NOT needed just to bleed air)?
2) If Lower Radiator Hose is disconnected from Thermostat @ "Quick-Disconnect", will Coolant from Block flow "Backwards" through Themostat & drain?
3) If the Answer to #2 is NO, can one safely Activate the Thermostat bulb heater element for ~ 30 Seconds to open the thermostat & drain the block?

I can't believe no one has tested an old thermostat removed when replacing Coolant Pump.

George

[Efthreeoh]

Originally Posted by gbalthrop

I totally agree with your interpretation of the Flow Diagram. If I understand you correctly, you disconnect the U-Hose from the Thermostat, which would be on TOP of #3 in the Diagram. TIS & Bentley talk about disconnecting the "Quick-Disconnect" fitting at the LEFT of #3/Thermostat where the Lower Radiator Hose connects.

On my 328xi (any X-drive has more junk in the way of the Coolant Pump & Thermostat), it would be a LOT easier to disconnect that "Quick-Disconnect" fitting on the FRONT of the Thermostat. I would expect coolant to flow "Backwards" through the pump impeller just fine, and your description appears to confirm that.

My questions are still:
1) Does the Thermostat open when Bleed Procedure is run, and if NOT, how does coolant get out of Radiator (which is probably NOT needed just to bleed air)?
2) If Lower Radiator Hose is disconnected from Thermostat @ "Quick-Disconnect", will Coolant from Block flow "Backwards" through Themostat & drain?
3) If the Answer to #2 is NO, can one safely Activate the Thermostat bulb heater element for ~ 30 Seconds to open the thermostat & drain the block?

I can't believe no one has tested an old thermostat removed when replacing Coolant Pump.

George

Reading in other literature on the N52, I've learned the T-stat "fails open", which tells me it stays open and closes based on signal from the ECU. The entire cooling system is designed to meet low emissions on cold engine start. The coolant pump and T-stat work together to allow rapid heating of the cylinderhead to improve cold-start combustion is my understanding. So during the bleed procedure and with the ignition off during the drain process, I think the T-stat is normally open. When the T-stat fails, it usually is the heating element that breaks, which would control coolant flow via the ECU.

[gbalthrop]

Originally Posted by Efthreeoh

Reading in other literature on the N52, I've learned [A] the T-stat "fails open", which tells me [B] it stays open and closes based on signal from the ECU...The coolant pump and T-stat work together to allow rapid heating of the cylinderhead to improve cold-start combustion is my understanding.

[A] AFAIK, mechanical thermostats have been designed for Decades (Last Millenium ;-) to "Fail OPEN" so as NOT to cause engine damage. A COLD engine will start & run fine, but as you note, emissions and combustion efficiency suffer if the engine does not reach 190F or more. "Fail Open" is a function of the mechanical design of the T-stat, and NOT something unique to the "heated bulb" "MAP" KFK.

[B] AFAIK, the ONLY significant difference in the E9x "Characteristic Map Thermostat" or "KFK" (KennFeldKühlmittelthermostat) and the garden-variety mechanical thermostat is a heating element in the wax bulb of the "mechanical thermostat". The TIS circuit shows an Orange Power supply from a "Switched" Terminal 87 (KL87) fuse, and a DME-controlled ground which activates the heating element. See Y6279 in the Lower-Right of this TIS Schematic:
https://www.newtis.info/tisv2/a/en/e...ooling/lqgyKuz

While I agree that the DME control of the Thermostat opening is designed to allow more efficient operation at higher engine temperature, as I understand the system, the DME can ONLY OPEN the thermostat by heating the wax bulb. It CANNOT CLOSE the thermostat (there's NO Motor in the T-stat ;-) So that means that WITHOUT heat added to the wax bulb by the DME-activated heating/resistance element, the KFK will operate SAME as a mechanical thermostat from prior millenia. Only difference is that the opening temperature, WITHOUT "added heat" from DME, is HIGHER than old-style T-stats to get better emissions. That means if engine operating conditions suggest, heat is added to bulb to open T-stat diaphragm more fully, or at lower Coolant Temp. Here is the only article (rather cursory ;-) I have found which appears to confirm the interpretation above:
https://us.autologic.com/news/electr...t-how-it-works

It appears to me that BMW is NOT particularly interested in having "Anglo's" at least in the US, actually understand how their vehicles work. I'm NOT sure that the German market is much different, but I have a sneaking feeling that if one were to search for "Kühlmittelthermostat"," or "KennFeldKühlmittelthermostat" and translate a few German Web pages, there is info to be had.

George

[MightyMouseTech]

Originally Posted by gbalthrop

[A] AFAIK, mechanical thermostats have been designed for Decades (Last Millenium ;-) to "Fail OPEN" so as NOT to cause engine damage. A COLD engine will start & run fine, but as you note, emissions and combustion efficiency suffer if the engine does not reach 190F or more. "Fail Open" is a function of the mechanical design of the T-stat, and NOT something unique to the "heated bulb" "MAP" KFK.

[B] AFAIK, the ONLY significant difference in the E9x "Characteristic Map Thermostat" or "KFK" (KennFeldKühlmittelthermostat) and the garden-variety mechanical thermostat is a heating element in the wax bulb of the "mechanical thermostat". The TIS circuit shows an Orange Power supply from a "Switched" Terminal 87 (KL87) fuse, and a DME-controlled ground which activates the heating element. See Y6279 in the Lower-Right of this TIS Schematic:
https://www.newtis.info/tisv2/a/en/e...ooling/lqgyKuz

While I agree that the DME control of the Thermostat opening is designed to allow more efficient operation at higher engine temperature, as I understand the system, the DME can ONLY OPEN the thermostat by heating the wax bulb. It CANNOT CLOSE the thermostat (there's NO Motor in the T-stat ;-) So that means that WITHOUT heat added to the wax bulb by the DME-activated heating/resistance element, the KFK will operate SAME as a mechanical thermostat from prior millenia. Only difference is that the opening temperature, WITHOUT "added heat" from DME, is HIGHER than old-style T-stats to get better emissions. That means if engine operating conditions suggest, heat is added to bulb to open T-stat diaphragm more fully, or at lower Coolant Temp. Here is the only article (rather cursory ;-) I have found which appears to confirm the interpretation above:
https://us.autologic.com/news/electr...t-how-it-works

It appears to me that BMW is NOT particularly interested in having "Anglo's" at least in the US, actually understand how their vehicles work. I'm NOT sure that the German market is much different, but I have a sneaking feeling that if one were to search for "Kühlmittelthermostat"," or "KennFeldKühlmittelthermostat" and translate a few German Web pages, there is info to be had.

George

No, the thermostat is not open unless it is up to temp. The only thing the electrical connection does in the thermostat is operate a heater, when turned on, will lower the operating temp of the cooling system.