Question about BMW 318

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I have continuos air bubbles from my expansion tank on my 1995 318i e36 4cylinder bmw

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Ahmed Mansour

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If you mean boiling water, it is unfortunatly the gasket of engine block need to be changed.

Posted on Mar 31, 2011


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1990 BMW 525i 2.5L engine overheats after rplaceing water pump, stermostat,fan clucth,radiator

There's trapped air in the cooling system.
  • You need to remove the bleeder screw on top of the radiator when adding water to the expansion tank.
  • With the engine running, pour water into the expansion tank till you see air go out through the bleeder screw's hole.
  • Just keep adding water until no more air bubbles come out then just put the screw back in place.
  • Then fill the expansion tank to it's normal level/line.



May 07, 2014 | 1990 BMW 525i

1 Answer

Radiator lock

Do you mean trapped air in the system? Put on all the caps and run the motor up to operating temp, drive it around to circulate the water. The bubble will migrate to the expansion tank, all by itself. Allow the motor to completely cool off, and it will draw water from the expansion tank. If you notice the expansion tank has a lower coolant level, the bubble has escaped.
These systems are engineered to do this automatically. A system needing bleeding would be bad engineering.

Dec 01, 2013 | Cars & Trucks

1 Answer

2004 bmw 325ci water leaking under expansion tank

remove the expansion tank and have a look at the seams those tanks have a habit of distorting and start leaking

Feb 07, 2013 | 2004 BMW 325i

1 Answer

Runs hot after i put antifreeze in it

more than likely you have air in the system,,,make sure you take the bleed valve fitting out of the expansion tank feeder line..crank the car up and turn the ac on wide should see bubbles flowing from the removed expansion feed bleeder screw.When the bubbles stop place the bleeder screw back into the housing.Let me know.

Aug 02, 2011 | 2003 Jaguar X-Type

1 Answer

If expansion tank was low on coolant, will this cause my bmw to overheat? and where is the expansion tank located on my car?

Under filled cooling systems generally do not cause a "hot" running vehicle, there is most likely a mechanical problem some where. the expansion tank on all BMW's is usually a "yellowish" colored reservoir with a black cap, the only exception is the later models that have the expansion tank attached next to the radiator (they are black with a black cap.

Apr 26, 2011 | BMW 325 Cars & Trucks

1 Answer

I have a 2005 325i, my car started overheating all of a sudden, I noticed that I had a pin hole in the expansion tank. I bought a new expansion tank along with a new thermostat located in the bottom of the...

A BMW that is hot after only two or three miles generally has air in the cooling system. Did you turn on the key and turn up the heater to open the heater valve, and then pour water unto the expansion tank until pure water came out of the bleed screw?

Feb 17, 2011 | BMW 325 Cars & Trucks

1 Answer


Are you talking the expansion tank? If so - Drain coolant first by going underneath the car and take off the protective shield and unscrewing the blue plastic screw (make sure the car is NOT hot!), under the reservoir you'll see an electronic sensor - carefully twist is a 1/4 turn counterclockwise and gently pull downward to remove this sensor don't force it, you don't want to pay $150 to replace it. Disconnect the hoses on the top and bottom of expansion tank by pulling up the metal tabs upwards then pulling the hose away from the tank. I believe there are two or three screws which hold the expansion tank bracket in place, unscrew these and pull the bottom of the tank away from the radiator then lift upwards on the bracket (the bracket and expansion tank should then come out). Get the old expansion tank off the bracket and replace. You want to take off the bracket because getting a new tank on the bracket is a B*TCH!

Reconnect in reverse order.

Make sure to bleed the cooling system properly to remove air pockets (please use BMW coolant and distilled H20 in 50/50 mix - it's not the same as your Prestone or other mass produced coolants). Last replace the expansion tank cap because that might have created the expansion tank cracking.

Good luck and hope this helps

Dec 16, 2010 | 1999 BMW 323 Series

1 Answer

Hi... are there some especial considerations to take during the replacement of the cooolant expansion tank?, like bleeding procedure, tips, etc Range Rover 2004, Thanks a million gabe

Hi, as you discovered the expansion tanks fail. There is an air bleed screw on the top of the new tank. I usually do not use the screw, refill coolant let the car warm up fully with the pressure cap off air will bubble up out of the system.

Nov 21, 2010 | 2004 Land Rover Range Rover

1 Answer

Why did my 320d, E46, water hose burst?

It could be due to age. Split hoses aren't uncommon.
However, it could be due to either a radiator blockage or a cylinder head problem - which is allowing exhaust gases to find their way into the cooling system via a leaking head gasket. When this happens the cooling system becomes pressurised by the exhaust gases.

To check if your radiator is blocked, run the engine until it is hot. The coolant goes into the radiator via the top hose and into the engine through the bottom hose.

Carefully feel the top and bottom hose. If the bottom hose feels much cooler than the top hose, then that indicates a radiator blockage. If the bottom hose feels 'flat' and 'squashed' that is another indicator - though it also can point to head gasket problems.

To check if there are head gasket problems, first check the oil on the dipstick. If it is a 'creamy sludge' then that indicates coolant has found its way into the lubricating system via a leaking head gasket.

Also remove the cap from the raditor expansion tank (where you fill it with coolant/water). Is there any sign of oil/sludge in the expansion tank? Another sign of head gasket problems.

With a COLD engine, remove the cap from the radiator expansion tank and then fire the engine up. Watch the coolant as the engine ticks over ... at first bubbles will appear as air in the coolant escapes. The bubbles should stop after a few moments as the engine warms. If the bubbles continue -or there is 'violent bubbling' that's teling you there is a head gasket problem.

I presume that your car hasn't been overheating or 'running rough' at times, as you haven't mentioned that. Overheating and 'running rough' can also be symptoms of head gasket problems.

All being well .. no radiator blockage or apparent head gasket problems, it is more than likely that the hose burst due to age/mileage.

Aug 16, 2010 | 2000 BMW 3 Series

1 Answer

How do you vent thermostat on 325E (1985)? I replaced my upper radiator hose and I have a feeling thermostat will not open. Thanks for input on this matter.

There should be 2 bleeder screws in the system, one on the expansion tank, and one on a thermostat housing. Open both screws all the way. Turn the key to the On postion (but dont start the car). Then turn the heater to max heat, but have the fan set at the lowest setting. Fill the expansion tank til coolant comes out of both bleeder screws with no bubbles. After that close the screws (be very careful not to over tighten them!!). Then completly fill the expansion tank. (dont mind the full mark, if theres air in the system, it will drop the level in the expansion tank) And thats it. Drive the car around then check the level.

Mar 01, 2009 | 1985 BMW 3 Series

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