E30 Zone

Right tried to bleed coolant system by all methods on this forum,now seem to be worse off now than I was before .
expansion tank takes in water then happily starts to spew it all out again, heater started to blow cold until I took her out on a very quick drive and then they blew hot again, although the temp gauge went nearly to the red.

The coke bottle method seemed to be working but failed when the bottle lost its shape.and wouldnt seal on the neck of expansion tank.

Kinking overflow hose opening bleed screw and filling expansion tank then blowing down it until fluid came out of the bleed screw kinda worked but fluid came straight out of bleed screw so dont know whats happening there.

Not quite sure what is wrong now apart from I have a huge airlock in the cooling system, everytime I have the engine running and I sqeeze hoses the expansion tank just keeps overflowing, its got to the point now where I dont seem to be able to squeeze hoses expell air refill expansion tank etc before the engine temp gauge swings towards the red zone.

Anybody got some more hints thanks for yours Blitz mate think I done it right.

325I M20 Touring

Why are you rebleeding what has changed?

I found getting the front of the car as high as possible helped a treat.

Try filling the tank and opening the bleed screw when its cold i got alot of air out that way before i even started it.

Last time i did mine i tryed to get as much air out first then stated it ran it up to temp and turned it off. Then came back when it was cold to fill the tank again.

Im bleeding because when I had the stat changed it wasnt bled just topped up and the temp gauge has always since read half way to three quarters dropping only when i turn on the heaters.
reading through the threads that was running a little too hot, and as it hadnt been bled I decided to do it, I,m pretty handy with the spanners but it looks like im a complete twonk on this, first time for everything I suppose.

I had the same trouble, and fixed it with changing the radiator. Coolant in it wasn't flowing nice. The radiator was extremly hot at one side and cold on the other...

Waterpump can be a problem as well.

I tried bleeding it with the front of the car as high as possible like up a steep drive, opened the bleed screw on top of the radiator loads of air came out, while cold. Then topped up more into the expansion tank, turned the heaters to fully hot and interior fan on 4, let the car run for 10-15mins then open the bleed screw again on top of the radiator. To get more air out, be careful here and don't snap the screw like I have just done. All should be well after this. Now I have to get a replacement screw from the dealers - oh well its 18 year old plastic and was probably brittle.
Hope this helps.

Nuvolari, swinster, many thanks for your info guys, nuvolari, do you think it might be worth flushing the cooling system first before I go down the road of changing the rad?
Swinster, how comes you have a plastic screw, where abouts is this, I have a meteal one on my stat, and no other bleed screw as far as I know. Im running a 325i m20 1988 touring.

swinsters car is a 4 pot. they have plastic ones on the rad.

Before you start, make sure you can open and close the air vent screw on the top of the thermostat housing.
Drain the rad by pulling off the bottom hose or unscrewing the drain valve. Good idea to take the top hose and vent hose off as well, pull out the two fixings for the top of the fan shroud, unscrew the two large self tappers that hold the rad top, and lift the rad out.
Backflush it from bottom to top and wash the matrix out from back to front as well. Don't go too mad with the pressure, or all the fins on the core will bend over or worse.
Good time now to check out the distributor cap and rotor, and copper grease up the cap bolts, or even to fit a new cam belt.
There is a drain plug (19mm) for the block hidden near the back of the engine under the exhaust manifold. Don't expect to have skin still on your knuckles if you undo this.
As an alternative, disconnect the header tank and connect the hose to your hosepipe, so that you thoroughly flush out the block with clean water.
Bear in mind that the old coolant should be properly disposed of.
Stick it all back together, turn the heater control to full hot, and a) if you drained the block, fill the system with a 40% mix of good quality antifreeze and water, or b) Pour in four litres of concentrated antifreeze, first and then top up with water.
Open the bleed valve on the thermostat untill all the air bubbles come out, close it again and knead all the rubber hoses at the front to shift all the air you can.
Helps if the front of the car is slightly higher than the back.
Keep the header tank topped up with 40% mix, and open the bleed valve again.
Put the radiator cap back on and start the engine. Keep a look out for leaks, put most importantly, put the heater blower on about 2, with the heat control full on and the lower lever to the right. As the car warms up, watch the temp gauge, and check that noticeablt warmed air is coming from the heater after about a minute or so.
Before things get too hot, take off the rad cap again, and check and top up the level again.
If the heater gets hot, then all is well, but if it doesn't and the gauge begins to climb past where it should, then you have an airlock, which can potentially crack the head.
To get rid of this airlock, let things cool so that you can remove the rad cap, and fill the header tank right up. Unscrew the jubilee clip fixing the top heater hose where it goes through the bulkhead, and pull the hose off. Coolant and hopefully air will come out. Let a cupfull or so of coolant out and fix the hose back on. Check the coolant level, put the rad cap back on and try again for output from the heater.
After a while, and after the car is cool again, try the bleed screw again.
You will probably find that it takes about a week fo all the air to come out, and the coolant level to stop dropping.
Finally, if your radiator cap has a black plastic disc on the bottom, rather than a yellow one, take your VIN down to the dealer, and ask for a free new one.

Found this using the search function, the zone is really helpful as is the search function. Been using the site for a while lurking and researching its all good.

Many thanks swinster, an awful lot of detail there and well put together, just had a sniff test done on me coolant to see if any exhaust gasses were present and thank the lord none were PHEW!!!!.
Anyway Ive got a squeek coming from the front of the motor I suspect that its the water pump on its way out, anyway I need to change the cam belt so ive done the easy option and told the garage they can do the work,
New cam belt
New tensioner
New pulleys
New water pump
All in including labour and VAT £223.50......... Not to bad a price I reckon, and as they will then have to bleed the system Im happy
At the moment she seems to sitting around the half way mark on the temp gauge with a slight rise when in traffic so im happy for now.