BMW M20 Coolant Bleed!!! HELP!

Hey guys..im new to the forums but i have a 1990 BMW 525i with a M20 engine and having alot of problems bleeding the thing! There is a lot of air and when I open the bleed screw next to the rad. cap and t stat housing, there is barely any bubbles coming out of the bleed hole next to the rad cap but a lot of pressure from the t stat! Climate control is full hot and still nothing! any tips?

Welcome to the Fest. I'm not real familiar with the M20. Sorry. Have you checked the procedure in the Bentley manual?

There is a link to a searchable copy here on the fest.

Give it a go per the manual and see if that doesn't do it for you.

Hope this helps a little.

You open the bleed screw and its just rushing air? No coolant what so ever?

There is sometimes coolant gushing out but mostly air from the tstat housing and not much from the bleed hole next to the radi. Also the hoses are filled with a lot of pressure!! I have watched YouTube and other cars looked in the Bently Manual... dont know what im doing wrong!!!

Are you overheating ? What work did you do recently on the car ? What do you mean by your thermostat giving you pressure ?

The radiator is easy to bleed on both engines, provided instructions are followed and nothing else is wrong the cooling system proper. And no matter what there will be some air left in the system, which is designed for.

Well not yet i always shut my car off before the temp goes to the red mark. And i have just replaced the headgasket. What i mean by the thermostat housing giving me pressure is that when i open the screw on the top of the housing there is alot of air pressure, so i tighten it when i see coolant flowing out but the temp still goes up so i have to open the screw again and there is a lot of air pressure in the hoses and coming from the t stat housing. Thnx for the replies guys

Turn the Engine OFF.
There are 2 bleeder screws.

the one by the expansion tank cap and the one on the thermostat housing.

Also: the manual makes it sound so easy, its not.

Follow these:
Just to share a simple method to bleed the cooling system.I really cannot comprehend why we need to bleed,bleed and re-bleed the cooling system after every maintenance.I did this after replacing the thermostat and flushing the coolant:
(Mine's an m20 engine with the reservoir by the side of the rad)
1.Fill up the rad with the plastic bleeder screw(on reservoir) and metal bleeder screw(on t-stat housing),open.
2.When full,put a finger over the reservoir bleed hole and blow, yes, blow into the reservoir filler neck.(we are basically pressurizing the system)
3.When water flows out of the t-stat housing bleed hole,tighten its screw while still blowing.
4.Top up reservoir as needed.
5.Now blow again until coolant exits the reservoir bleed hole and tighten when bubble free.
6.Top up coolant to the cold/kalt mark,tighten cap.You're done. No more bleeding required as all air is purged from the system. I have done this 4 times on three cars and it worked like a charm.

You heard it right, blow. trust me it works, and make sure your heater is on full blast as well.

Can i use an air compressor to blow air instead? And your right the manual is useless for bleeding!!! Also do i need to turn the ignition to the ON position or??? ANd thank you for the reply

Yes, ignition position II, both dials to hot and set blower to warpspeed 4 (haha!).

You can use compressed air if you can find an adapter that will make a tight seal over the reservoir neck.


One more thing...before doing the blowing, remove both bleeder screws, then clean out the bleeder holes with stiff wire or pipecleaners. Once those holes are clear of debris fill up the reservoir until coolant overflows from all 3 orifices: the reservoir, and both bleeders. Then you can remove a bit of coolant from the reservoir (so you aren't drinking the stuff) and begin blowing and bleeding with the heater on.

Alright I will try this...Thank you for all the help guys but idk why but the first two times i have tried to bleed the car the heater isn't blowing any hot air!!

Originally Posted by paperplane94

Turn the Engine OFF.
There are 2 bleeder screws.

the one by the expansion tank cap and the one on the thermostat housing.

Also: the manual makes it sound so easy, its not.

Follow these:
Just to share a simple method to bleed the cooling system.I really cannot comprehend why we need to bleed,bleed and re-bleed the cooling system after every maintenance.I did this after replacing the thermostat and flushing the coolant:
(Mine's an m20 engine with the reservoir by the side of the rad)
1.Fill up the rad with the plastic bleeder screw(on reservoir) and metal bleeder screw(on t-stat housing),open.
2.When full,put a finger over the reservoir bleed hole and blow, yes, blow into the reservoir filler neck.(we are basically pressurizing the system)
3.When water flows out of the t-stat housing bleed hole,tighten its screw while still blowing.
4.Top up reservoir as needed.
5.Now blow again until coolant exits the reservoir bleed hole and tighten when bubble free.
6.Top up coolant to the cold/kalt mark,tighten cap.You're done. No more bleeding required as all air is purged from the system. I have done this 4 times on three cars and it worked like a charm.

You heard it right, blow. trust me it works, and make sure your heater is on full blast as well.

There is no need to blow anything into the radiator, hoses, etc unless you find it interesting for its own sake. All you need is patience and to eliminate the superstition that every molecule of air in the cooling system needs to be evacuated if not you're going to overheat.

1. Bleed the car using the Bentley manual. After that, drive it for a day or two (the driving around is important) then bleed the car once again the next morning. So that's 2 bleeds. That's all you need to do.

2. When getting ready to bleed, bleed it when cold, then start the engine and let her warm up to optemp (operating temperature), activate cabin heat to max, then rebleed, fix the bleed screws back, top up expansion tank to the max, fasten the rad cap onto it (don't worry about compressing water etc), and then you're done. So that's another 2 bleeds.

I've been bleeding radiators on an m50 and m20 radiator for the past few years and this is all that ever needed to be done.

If despite doing the above, you are overheating or running hot, you've got a busted water pump or thermostat or something else that's wrong with your ride. Most people do, most previous owners neglect their E34s. So if you have no reliable evidence that these were changed in the past 2 years, please change them out immediately and you'll be saving yourself a whole lotta trouble unrelated to bad bleeding.

I have an important video to share with everyone that I took of my radiator 2 weeks back after changing it to a new one.

http://www.sendspace.com/file/uod87v

Padre, would you do me a big favour? Please upload that to youtube somewhere and pm the link to me. I'll construct a separate post around that. I am sure that it will be illuminating. If you can sir. Thank you.


rgds,
Roberto

I also have replaces the thermostat and water pump. Thnx for the advise

Originally Posted by BMWE34M20

I also have replaces the thermostat and water pump. Thnx for the advise

Then please do the bleeding as I have described, and if you continue to overheat, your new themostat is either buggy (it does happen but very very unlikely at this point) or you may other issues. You'll need to look into your fan clutch, your auxiliary fan, your rad cap and bleed screw, and if those check out, you'll need to start doing compression tests on your engine or picking up one of those quick and dirty solutions which will turn from blue to brown if there's combustion gases in your coolant, to see if you have a hg (headgasket) or other issue.

Take it one step at a time. Be calm and methodical. You're going to put this situation in the rearview mirror soon. Do the bleeding as I've described (and follow the manual's methods to the letter). So it will be a 2x2 bleeding, one extra bleeding the following day after some driving to give you upom (utmost peace of mind). Don't do any more bleeding if you notice more bubbles on the second bleed. Then monitor. If you've got more problems, then you need to start looking elsewhere.

Please do the stomp test if it works and see if there are any errors on your car, just to be thorough.


rgds,
Roberto

Originally Posted by paperplane94

Turn the Engine OFF.
There are 2 bleeder screws.

the one by the expansion tank cap and the one on the thermostat housing.

Also: the manual makes it sound so easy, its not.

Follow these:
Just to share a simple method to bleed the cooling system.I really cannot comprehend why we need to bleed,bleed and re-bleed the cooling system after every maintenance.I did this after replacing the thermostat and flushing the coolant:
(Mine's an m20 engine with the reservoir by the side of the rad)
1.Fill up the rad with the plastic bleeder screw(on reservoir) and metal bleeder screw(on t-stat housing),open.
2.When full,put a finger over the reservoir bleed hole and blow, yes, blow into the reservoir filler neck.(we are basically pressurizing the system)
3.When water flows out of the t-stat housing bleed hole,tighten its screw while still blowing.
4.Top up reservoir as needed.
5.Now blow again until coolant exits the reservoir bleed hole and tighten when bubble free.
6.Top up coolant to the cold/kalt mark,tighten cap.You're done. No more bleeding required as all air is purged from the system. I have done this 4 times on three cars and it worked like a charm.

You heard it right, blow. trust me it works, and make sure your heater is on full blast as well.

It looks like you're not bleeding the engine with it running and at optemp, which is wrong. You're not going to get much air trapped in the block out this way as the themostat needs to open for that to happen.. However, you've indirectly proven my point i.e. its ok to have some air in the engine/cooling system, in an otherwise well maintained vehicle. You're not going to run hot or overheat or anything else.

You start when cold (mainly because you have to start when its cold after all), do one bleed cause that's the easiest, leave the bleed screws off, start the engine and cabin heat on high, give it ten minutes to heat up, then bleed one more time, affix the screw as coolant is running out, top up the expansion tank to max, screw the rad cap on top, then you're done.

Paperplane, I'm sure what you've suggested works, if you've done it on more than one car and you're using it all the while with no issues. The laws of physics are not different for you and I. However, why don't you give my suggestion a try with an open mind since its easier, and see if that works ? Do it the next time you flush your radiator etc.


cheers,
Roberto

No you are right as well. My procedure gets rid of any air that is trapped before the thermostat, not the small amt. of air that's in the head due to a cold/closed thermostat. Therefore it is best for one to warm up the car after doing the blowing procedure above and crack the bleeder as the engine warms up to remove the air that was still trapped in the head.

I guess you could call it doing a cold bleed, then a hot bleed, for one full bleeding process.

The t'stat is vertically mounted. Drill a 1/16" hole in the flange and set that at the top. air will pass through and speed up the process. My E23 will bleed cold with the engine stopped. Then re bleed after a day or so.

Wouldn't coolant rush out of the additional drilled hole when the system is hot and under pressure ?

I think this thread is spiraling out of control.

Everybody cool off and take a step back. Nothing needs to be drilled, nothing needs an air compressor, no corners should be cut, no get-rich-quick schemes. There's a right process and it requires patience and determination. It was posted above, start with that.

Thanks for the help everyone!! i will try rebleeding the car today!

Originally Posted by 95 E34

I think this thread is spiraling out of control.

Everybody cool off and take a step back. Nothing needs to be drilled, nothing needs an air compressor, no corners should be cut, no get-rich-quick schemes. There's a right process and it requires patience and determination. It was posted above, start with that.

+1

Sent from my Desire HD using Bimmer App

Originally Posted by BMWE34M20

Alright I will try this...Thank you for all the help guys but idk why but the first two times i have tried to bleed the car the heater isn't blowing any hot air!!

Your engine was not on, there was too little time for coolant to heat up, or your heater valve unit or its fuses are busted....this is quite common. If so, ignore this step in your bleeding procedure, there will be no mischief.

Paperplane94 you are a life saver!!! tht way is awesome and real easy!!! Car temp stayed in the middle and runs like a beauty!! Just gotta run some tests and check she's ok!! THANKS FOR THE HELP EVERYONE!!

Happy endings, love em.

Keep a cat eye on the temp gauge for the next few days, and do you have cabin heat?

Yes strted driving it finally worked happy about that....gauge is straight in the middle and im strting to get really happy!! Cuz i have put a lot of money into this tough little bimmer!! Had it ever since it was new!

Original owner, Nice!