No heat after expansion tank replacement

My expansion tank blew out on new years eve. Luckley I was able to make it home before temp got up to the 3/4 mark on temp gauge. Anyway I was planning to replace the cooling system this spring since I am new to this car per mangos thread. Being that it happend right after xmas I was only able to afford replaceing the minimum to get back on the road.
I purchased a new tank and a gallon of bmw antifreeze from the dealer. I replaced tank then filled system with 50/50 mix of antifreeze and distilled water and bled as described in mangos thread. All seemed good at first but now I am only getting heat for a few min after engine warms up then it goes cold. While hot if I remove the tank cap it relieves the pressure and heat is fine until the motor cools off then the same thing happens on the next warm up cycle. The upper and lower hoses are as hard as a bike tire until I open the cap to relieve pressure. The level of the coolant is in the middle of the high low mark when cold. I has been so for the last few warm up cycles. When I take off cap while hot I hear air esacape then if I squesse rad hose the put cap back on I can hear air go back into tank but then if a squese the hose with cap on no air comes back out.

My question is can the tank cap be causing an over pressureizing of the system not allowing the coolant to pass thru heat circuit? or possible bad HCV? Waterpump?

The heat worked fine before the tank let go. It was slow to put heat into the cabin until the engine was up to operating temp but work great after that.

I am a marine service teck with over 20 years exp so I know my way around and engine but not an expert on closed cooling systems as we dont use them often on inland lakes.

I plan to purchase a new cap for the tank in the new few days to see if that fixes the problem but I wanted to see if anyone has seen this before.

Thanks

Try bleeding again. Engine off and heat set to max.

I have bled the system 3-4 times with heat all the way up and car not running and each time after the first I really never got anymore bubbles out if it. The first time I jacked up the front of the car about 18" off the ground with the drivers side a little higher than the passenger side. I was able to get almost all of the 2 gal of 50/50 mix in. What gets me is that if I take the cap off after it's warm I have plenty of heat.

Originally Posted by farkas330i

I have bled the system 3-4 times with heat all the way up and car not running and each time after the first I really never got anymore bubbles out if it. The first time I jacked up the front of the car about 18" off the ground with the drivers side a little higher than the passenger side. I was able to get almost all of the 2 gal of 50/50 mix in. What gets me is that if I take the cap off after it's warm I have plenty of heat.

The car needs to be running.

Originally Posted by farkas330i

I have bled the system 3-4 times with heat all the way up and car not running and each time after the first I really never got anymore bubbles out if it. The first time I jacked up the front of the car about 18" off the ground with the drivers side a little higher than the passenger side. I was able to get almost all of the 2 gal of 50/50 mix in. What gets me is that if I take the cap off after it's warm I have plenty of heat.

Search for me and 'alternative bleeding method'--think I put it in Mango's thread.

Having heat on with car off won't bleed after you've already filled the car...wp isn't moving.

Try my method.

You're welcome! lol

Maybe it got hot enough to blow the head gasket? Hope not.

Check your water pump

OP: You'll need way more than two gallons to complete the fill and bleed procedure. Two gallons is just to fill it. You'll need at least an extra gallon to force all the air out of the system. Lots of water will be on the floor if you've done the job properly.

x1000 on bleeding.

Definitely didn"t get hot enough to blow head gasket. Barely made it to the 3/4 temp mark. I definitely did not run enough to dump a whole lot on the ground so I will buy another gallon of antifreeze as well as distilled water and pump some more though it. Now that I am at the point I am, how should I continue to bleed it? Warm with car running or cold with motor not running? I would assume with heat all the way up in both situations as well as nose jacked up to help air get to front.

Thanks for all the responses.

Originally Posted by farkas330i

Definitely didn"t get hot enough to blow head gasket. Barely made it to the 3/4 temp mark. I definitely did not run enough to dump a whole lot on the ground so I will buy another gallon of antifreeze as well as distilled water and pump some more though it. Now that I am at the point I am, how should I continue to bleed it? Warm with car running or cold with motor not running? I would assume with heat all the way up in both situations as well as nose jacked up to help air get to front.

Thanks for all the responses.

The only thing that happens with the heat on is the heater valve opens allowing hot coolant into the heater core

You need the car running to allow the water pump to circulate coolant and force air to the bleeder screw and cap.

Originally Posted by farkas330i

Definitely didn"t get hot enough to blow head gasket. Barely made it to the 3/4 temp mark. I definitely did not run enough to dump a whole lot on the ground so I will buy another gallon of antifreeze as well as distilled water and pump some more though it. Now that I am at the point I am, how should I continue to bleed it? Warm with car running or cold with motor not running? I would assume with heat all the way up in both situations as well as nose jacked up to help air get to front.

Thanks for all the responses.

Use my 'alternate bleeding method.' It's from a bmw tis...you can trust me.

Originally Posted by 7xWDC-MSC

The only thing that happens with the heat on is the heater valve opens allowing hot coolant into the heater core

You need the car running to allow the water pump to circulate coolant and force air to the bleeder screw and cap.

Per BMW TIS, the bleed process is done with the engine off. The engine is not airlocked. Air will naturally find its way out with the engine off and thermostat closed.

Running the engine introduces the risk of an overheat while you're bleeding, heats up the expansion tank which increases the chance you'll damage the threads or the bleed screw when reinstalling it since the parts will have expanded. It also introduces the risk of injury due to hot coolant.

Originally Posted by E46Mango

Per BMW TIS, the bleed process is done with the engine off. The engine is not airlocked. Air will naturally find its way out with the engine off and thermostat closed.

Running the engine introduces the risk of an overheat while you're bleeding, heats up the expansion tank which increases the chance you'll damage the threads or the bleed screw when reinstalling it since the parts will have expanded. It also introduces the risk of injury due to hot coolant.

Do you have a link to this TIS, apparently thespaghetticoders link was removed by BMW?

Also since coolant/water will expand when hot, your level won't be correct.

Since I have apparently bled the system incorrectly should I drain the system from the drain in the ET and start over?

Dmax- I searched through mango's cooling guide for your post about your alternative bleeding method but couldn't find it. Poss I overlooked since there is over 800 posts.

I did notice the difference in the hot and cold level is different from the expansion of the coolant being hot.

Has anyone put a clear hose over the bleed screw hole or thread a barb with hose on it and pumped it back into the ET as to not waste a bunch of fluid on to the ground or into a drain pan? Just a thought I had.

With the car cold...fill ET to between min and max. Close ET cap. Don't touch bleeder screw.

Key to pos 2...heater on highest temp, fan on low, 3 red dots on the dial between vents

Then start the car, rev to 3-4K rpms for 20 secs. and turn the car off.

Then open ET...add coolant if needed.

Repeat if needed. Do not overfill...stay below the max level on the dipstick.

This way you push air out, don't heat up the car, and the coolant level will reflect a true level...not the level it takes when it's hot.

You don't need to drain at this point. We're assuming you have an air bubble somewhere in the system that's preventing the flow to the heater core...the revs to 3-4K should take care of that.

HTH

[QUOTE=dmax;15036849]With the car cold...fill ET to between min and max. Close ET cap. Don't touch bleeder screw.

Key to pos 2...heater on highest temp, fan on low, 3 red dots on the dial between vents

Then start the car, rev to 3-4K rpms for 20 secs. and turn the car off.

Then open ET...add coolant if needed.

Repeat if needed. Do not overfill...stay below the max level on the dipstick.

This way you push air out, don't heat up the car, and the coolant level will reflect a true level...not the level it takes when it's hot.

You don't need to drain at this point. We're assuming you have an air bubble somewhere in the system that's preventing the flow to the heater core...the revs to 3-4K should take care of that.



Thanks for the breakdown. I will give that a try and post my results. May be a few days.

No fan clutch. It is a manual. The water pump seems to be working as there is a steady stream of fluid coming into the air chamber of the ET. I believe that is what that means anyway.

Thanks for the replys.

Check water pump .also check ur fanclutch make sure u can not stop it with ur hand .make sure it is spinning all the way.

Sent from my SPH-D710BST using Bimmer App

This always work for me if multiple bleeding attempts failed, start car, set temp to max and fan to high. Set car on neutral and rev eengine pass 4
Rpm. Do this a few times and hold the rev for a few seconds also.

I hope this helps. Good luck and update us