Water Circulation

[julielewis]

My 1989 520i e34 m20 is driving me crazy. I changed the cylinder head, cylinder head gasket, water pump, thermostat and there seems to be no water circulation. Could this be due to an incorrect cylinder head gasket? How do I know if I am getting the right one?

Julie

[Ross]

Check to see if the thermostat is installed backwards.

[julielewis]

The thermostat is in the proper way. I think they might have sold me the wrong head gasket. The thing is my car is a 520i and I think they might have sold me the head gasket for the 525i. I am going to change it tomorrow.

[gmannino]

Could be a clogged radiator. Remove and have a radiator shop test for flow. Chocolate milk (oil and water) mixed can clog the radiator, thus preventing flow. How do you know you're not getting flow? Did you properly bleed the cooling system?

Its very important to bleed ALL air out of the cooling system or you will continue to overheat!!!

[Ross]

I have zero experience with a 2 liter engine as they aren't sold here.
Assuming the only difference between the 2.0 and the 2.5 is bore and stroke the fire ring would be too large(not enough to impose on coolant passages) if the 2.5 gasket was used. I cannot conceive how this would effect coolant circulation.
What are the circumstances that led you believe you don't have circulation?

[Dr. evil]

could be the head gasket. did you make sure that all the holes around the cylinder have matching holes in the gasket?

[julielewis]

I checked the head gasket yesterday and it is the one for the 2.0 l engine which is the right one. The radiator was checked and it is fine. What the mechanic explained is that the flow of water from the radiator to the expansion tank is minimal when he compared it to a similar car. I am a novice at this so bare with me if I don't make much sense:-)

[DaveVoorhis]

You've just pulled the head because the trickle of water from the rad core to the expansion tank was, er, minimal? I assume you're now going to install a new head gasket and new head bolts, yes?

It sounds to me like the system was poorly bled, or the rad has deposits and/or corrosion at the top, or both.

[Jon K]

Wow a lot of work for a lot of nothing.

Is the car over heating? What is you reasoning for worry?

[E34-520iSE]

Hi Julie,
I have the same car/engine as you. I know what these things are like for setting up the cooling system - they are a pain to bleed, which is due to the M20B20 having no aux. water pump. Use my tried-and-tested-many-many-times 'Crazy Shaun' bleeding method and your heaters will be hot, your engine will be well cooled and the temp guage will stay central. Takes less than 5 minutes start to finish.

HTH,

Shaun Marsh

[julielewis]

Hi Shaun
Can you tell me what your "crazy Shaun" bleeding method is.

Julie

[julielewis]

I just installed a new head and head gasket etc because I had a cracked cylinder head etc. I definitely would not let them pull the head because the water flow from the rad to the expansion tank was trickling. Hopefully on Monday I can get more work done on it.





You've just pulled the head because the trickle of water from the rad core to the expansion tank was, er, minimal? I assume you're now going to install a new head gasket and new head bolts, yes?

It sounds to me like the system was poorly bled, or the rad has deposits and/or corrosion at the top, or both.

[E34-520iSE]

I'll PM it to!

Cheers,

Shaun M

[Alan_525i]

Could you post it here so the rest of us could benefit from your knowledge as well? Or is it a trade secret?

[E34-520iSE]

Could you post it here so the rest of us could benefit from your knowledge as well? Or is it a trade secret?
Hi Alan, I used to post my M20 bleeding method on the UK BMW site. I got so fed up of people moaning about it that I have decided to keep it a 'trade secret'. What I will say is that it works 100% of the time on ANY car.

Cheers,

Shaun M

[DaveVoorhis]

Here's how I did it when I had an M20:

1. Open the rad and thermo housing bleed screws.

2. Pull the top hose off the rad. Fill through the hose until it won't take any more. Re-attach the hose.

3. Fill the expansion tank to the brim until it won't take any more.

4. Squish the rad hoses to expel air.

5. Put your mouth over/in (depends on size of mouth) the expansion tank opening and blow hard until coolant comes out the bleeders. Close the bleeders while still blowing.

6. Start the car, immediately rev briefly to 3500 or so rpm (voom! voom!) and shut off the car.

7. Top up the expansion tank. Open bleed screws and repeat the above.

8. Start the car, let it idle and verify it does not overheat.

9. Let the car cool overnight, and top up the expansion tank to the proper level.

[E34-520iSE]

Here's how I did it when I had an M20:

1. Open the rad and thermo housing bleed screws.

2. Pull the top hose off the rad. Fill through the hose until it won't take any more. Re-attach the hose.

3. Fill the expansion tank to the brim until it won't take any more.

4. Squish the rad hoses to expel air.

5. Put your mouth over/in (depends on size of mouth) the expansion tank opening and blow hard until coolant comes out the bleeders. Close the bleeders while still blowing.

6. Start the car, immediately rev briefly to 3500 or so rpm (voom! voom!) and shut off the car.

7. Top up the expansion tank. Open bleed screws and repeat the above.

8. Start the car, let it idle and verify it does not overheat.

9. Let the car cool overnight, and top up the expansion tank to the proper level.
Yep that's the way to do it! When I first posted this method on the UK board a few years back I got people complaining it was dangerous/poisonous/didn't work etc. It worked for Dave Voorhis, and many others too!

Cheers,

Shaun M

[DaveVoorhis]

Well, of course it's dangerous and poisonous, if you drink the coolant. Don't drink the coolant.

[Ferret]

Well, of course it's dangerous and poisonous, if you drink the coolant. Don't drink the coolant.

I'm strongly reminded of that 'Do Not Push' button in that one family guy ep...

Do these engines have the top expansion tank like the 535? If so, I'd make sure that the top bleed line isnt blocked at the expansion tank - they've got a nasty habit of doing that.

[DaveVoorhis]

Do these engines have the top expansion tank like the 535?
No, it's on the side of the rad.

[julielewis]

Finally got it sorted out. My brother decided to fix it himself. The previous mechanic that worked on the car apparently tried to lengthen the return hose and used some form of pvc to join the two hoses on the inside. Obviously when the water gets hot the pvc shrink and then restrict the water flow.

[messiahofpain]

check auxillary water pump if not then you must reverse flush the system some kind of blockage

[messiahofpain]

check auxillary water pump if not then you must reverse flush the system some kind of blockage in sytem