[bureau13]

So the car is still driving well after the valve cover gasket and oil filter housing gasket, etc, but of course something had to go wrong: Coolant is vanishing. I haven't seen any evidence of leaks other than the fact that it's low suddenly, but the person driving it said the yellow overheat light came on, and when they parked it, he saw green coolant at the front of the car.

I filled it, ran it a bit, and didn't see anything. He hasn't noticed an additional leaks either, but when we checked this morning the expansion tank itself was pretty much empty. That's no good. Anyway, I filled it again, this time remembering to crack the bleed screw (oops). When that was done, I attempted the bleed procedure, but no matter what I did, the water pump just would not kick in. I'm reasonably sure it's not because the water pump is dead, because it would overheat pretty quickly with or without a leak in that case, and that's not happening. Any idea what might cause the bleed procedure to not start?

[BashShah]

a Bad water Pump will cause a Bleed procedure to not come on.
also, does you fan run when you start the car, like super fast?
that's a sign of WP and Tstat.

[colorado.e9x]

If you have no symptoms of the water pump, it doesn't hurt to double check that you're doing the procedure correctly.

I reccommend using a battery tender while doing it

Open the expansion tank, keep the bleeder screw tight
Put the fob in and put it in accessory mode
Climate control at max heat, lowest fan setting
Push the throttle all the way to the floor for 10-12 seconds, should hear it start up and a trickling water sound

[bureau13]

Just checking myself: Putting it in accessory mode means pressing Start while NOT pressing any pedals, right? I can see lights come on on the dash, etc when I do it.

Also...the expansion tank cap should be off? That's not right is it?

The weird thing is, I did have some issues getting it to work when I changed the radiator, but it did finally work. I don't remember if I suddenly did anything different then though. That was in 2019 and as we all know, that was AGES ago.

Originally Posted by colorado.e9x

If you have no symptoms of the water pump, it doesn't hurt to double check that you're doing the procedure correctly.

I reccommend using a battery tender while doing it

Open the expansion tank, keep the bleeder screw tight
Put the fob in and put it in accessory mode
Climate control at max heat, lowest fan setting
Push the throttle all the way to the floor for 10-12 seconds, should hear it start up and a trickling water sound

[bureau13]

Originally Posted by BashShah

a Bad water Pump will cause a Bleed procedure to not come on.
also, does you fan run when you start the car, like super fast?
that's a sign of WP and Tstat.

I have not noticed a fast fan on startup, but I will check specifically.

[gjm120]

According to Bentley manual and BMW TIS, the bleeder screw and expansion tank are supposed to be closed during the venting/bleed process.

It seems logical that the tank should be open and many will advise so, but...

[theslowe90]

Go to autozone and loan a cooling system pressure test. See if pressure goes down at all.

[colorado.e9x]

Originally Posted by bureau13

Just checking myself: Putting it in accessory mode means pressing Start while NOT pressing any pedals, right? I can see lights come on on the dash, etc when I do it.

Also...the expansion tank cap should be off? That's not right is it?

The weird thing is, I did have some issues getting it to work when I changed the radiator, but it did finally work. I don't remember if I suddenly did anything different then though. That was in 2019 and as we all know, that was AGES ago.

Yes hit the start button without pressing any of the pedals, if you can turn the heater on then you're good to go.

I'm just telling you how I did it and I've had zero problems. Bleeder screw tightened, expansion tank cap off. Worked well for me

[rothwem]

Originally Posted by colorado.e9x

Yes hit the start button without pressing any of the pedals, if you can turn the heater on then you're good to go.

I'm just telling you how I did it and I've had zero problems. Bleeder screw tightened, expansion tank cap off. Worked well for me

what? really? You didn't get coolant everywhere? You're supposed to have the cap on.

For the OP: One reason that it potentially didn't start the bleed is battery level, I've heard that if your battery is not fully charged it won't do the bleed procedure.

Also to the OP: check the blue plug on the driver's side bottom of the radiator. Mine leaked there. I replaced it, was good for a couple months then I saw that the radiator end tank was cracked where the upper hose hooked on. The other likely spot for a leak is the nipple for the overflow hose that's on the upper radiator hose. It hooks to a thin hose that runs across the radiator support to the expansion tank.

[colorado.e9x]

Originally Posted by rothwem

what? really? You didn't get coolant everywhere? You're supposed to have the cap on.

For the OP: One reason that it potentially didn't start the bleed is battery level, I've heard that if your battery is not fully charged it won't do the bleed procedure.

Also to the OP: check the blue plug on the driver's side bottom of the radiator. Mine leaked there. I replaced it, was good for a couple months then I saw that the radiator end tank was cracked where the upper hose hooked on. The other likely spot for a leak is the nipple for the overflow hose that's on the upper radiator hose. It hooks to a thin hose that runs across the radiator support to the expansion tank.

No lol why would it? The water comes from the hose the bleeder cap is on, and into the tank. Theres no reason it should higher than that unless it was way overfilled

[gjm120]

For venting the cooling system...

https://www.newtis.info/tisv2/a/en/e...-parts/OYeyvvP

[bureau13]

This doesn't answer the bleeding question, but I think I found the leak. It looks like sometimes it bubbles/drips out where the driver's side end tank is attached to the core, near the top. I'm not sure why it doesn't do it more. I started it and idled it a few minutes ago for a good 15 minutes, and no leaks, but someone drove it and was idling waiting for someone to get out of their parking spot and it started leaking then. Possibly some BMW sorcery with the electric water pump, I don't know if they turn it on and off at times, unlike the mechanical pumps that God intended ;-)

This is doubly frustrating because it's essentially a new radiator. Silver lining is it's under warranty...

[Efthreeoh]

Originally Posted by bureau13

This doesn't answer the bleeding question, but I think I found the leak. It looks like sometimes it bubbles/drips out where the driver's side end tank is attached to the core, near the top. I'm not sure why it doesn't do it more. I started it and idled it a few minutes ago for a good 15 minutes, and no leaks, but someone drove it and was idling waiting for someone to get out of their parking spot and it started leaking then. Possibly some BMW sorcery with the electric water pump, I don't know if they turn it on and off at times, unlike the mechanical pumps that God intended ;-)

This is doubly frustrating because it's essentially a new radiator. Silver lining is it's under warranty...

Okay, so a little more information is helpful. Who replaced the radiator? My bet is the small nipple for the return line that is on the top of the upper radiator hose connector is cracked and is leaking under pressure (when the coolant expands due to heat). Mechanics tend to break the nipple when working on the cooling system. Repair is a new upper radiator hose.

[bureau13]

That was a good guess, because I initially did that (I'm the "mechanic" in question). However I replaced that hose, and it's dry. I have a video but can't seem to get it to play on my computer at the moment. It really does appear to be bubbling out where the plastic end piece meets the aluminum core.

Originally Posted by Efthreeoh

Okay, so a little more information is helpful. Who replaced the radiator? My bet is the small nipple for the return line that is on the top of the upper radiator hose connector is cracked and is leaking under pressure (when the coolant expands due to heat). Mechanics tend to break the nipple when working on the cooling system. Repair is a new upper radiator hose.

[Efthreeoh]

Originally Posted by bureau13

That was a good guess, because I initially did that (I'm the "mechanic" in question). However I replaced that hose, and it's dry. I have a video but can't seem to get it to play on my computer at the moment. It really does appear to be bubbling out where the plastic end piece meets the aluminum core.

Then it really just sounds like a manufacturing defect in the radiator. Good luck with the repair.