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Coolant Expansion Tank Replacement
 

Pelican Technical Article:

Coolant Expansion Tank Replacement

Nick Czerula

Time:

2 hours2 hrs

Tab:

$200

Talent:

***

Tools:

T25 Torx driver, flathead screwdriver

Applicable Models:

BMW 525i/xi Sedan (2004-07)
BMW 528i/xi Sedan (2008-10)
BMW 530i/xi Sedan (2004-07)
BMW 530xi Wagon (2006-07)
BMW 535i/xi Sedan (2008-10)
BMW 535xi Wagon (2008)
BMW 545i Sedan (2004-05)
BMW 550i Sedan (2006-10)

Parts Required:

Expansion tank, radiator hoses, engine coolant

Hot Tip:

Work with a cool engine

Performance Gain:

Car will cool down again, coolant leak repaired

Complementary Modification:

Change the radiator hoses and flush the cooling system

The BMW E60 cooling system is filled through the plastic coolant expansion tank (or coolant reservoir) at the right front of the engine compartment. There is no cap on the radiator. Other components of the cooling system consist of:

  • M54 and 8-cylinder engines: Belt driven coolant pump bolted to the front of the engine block.
  • N52 and N54 engines: Electric coolant pump bolted to the right front of the engine block.
  • Electric cooling fan attached to rear of radiator. The cooling fan is controlled by the engine control module (ECM) via an output final stage.
  • Electrically heated thermostat.
  • Automatic transmission cooler (heat exchanger).
  • Heater valve and heater core (for climate control).
  • Coolant level sensor inside expansion tank.
  • Coolant temperature sensor at cylinder head.
  • Coolant hose and lines.

When a coolant expansion tank ages it becomes brittle and develops hairline cracks. Inspect your expansion tank every time you change your oil. Look for cracks or any signs of leaks. Ignoring a small crack is a bad idea, as they can grow rapidly and create a major coolant leak before you know it. The coolant level sensor is located in the bottom of the tank. If you have a low coolant level message, but your coolant level is OK, you may have a faulty sensor. In this tech article I will show you how to replace the expansion tank and test and replace the coolant level sensor.

Do not remove the expansion tank cap while the engine is hot. Coolant or hot steam may escape and will scald you. To do any work on the cooling system, wait until the engine has cooled off.

Keep in mind that when your car was serviced before, parts may have been replaced with different size fasteners used in the replacement. The sizes of the nuts and bolts we give may be different from what you have, so be prepared with different size sockets and wrenches.

Protect your eyes, hands and body from fluids, dust and debris while working on your vehicle. If you're working with the electrical system, disconnect the battery before beginning. Always catch fluids in appropriate containers and properly dispose of any fluid waste. Recycle parts, packaging and fluids when possible. Do not work on your vehicle if you feel the task is beyond your ability.

Vehicle models change and evolve as they grow older, so the vehicle shown in our illustrations may vary slightly from yours. If something seems different, let us know and share your info to help other users. Do you have questions or want to add to the article? Leave a comment below. When leaving a comment, please leave your vehicle information.

Remove the engine splash shield. See our tech article on splash shield removing.

Drain the cooling system. See our tech article on cooling system draining and filling. You do not have to drain the cooling system completely, just enough to lower the level to drain the expansion tank. You can also clamp off the coolant hoses to prevent leaking coolant when removing the expansion tank.

The coolant expansion tank is located on the right (passenger) side of the engine compartment (green arrow).
Figure 1

The coolant expansion tank is located on the right (passenger) side of the engine compartment (green arrow).

6-cylinder engine: Models with a 6-cylinder engine have a single hose to the top of the expansion tank and a cap.
Figure 2

6-cylinder engine: Models with a 6-cylinder engine have a single hose to the top of the expansion tank and a cap. I suggest replacing the cap when servicing the tank. Working at the top of the coolant expansion tank, using a flathead screwdriver, release the upper hose retaining clips (green arrows) by prying up. Lever the clip up until it reaches the stop (yellow arrow).

8-cylinder engine: Models with an 8-cylinder engine have two hoses at the top of the expansion tank.
Figure 3

8-cylinder engine: Models with an 8-cylinder engine have two hoses at the top of the expansion tank. Working at the top of the coolant expansion tank, using a flathead screwdriver, release the upper hose retaining clips (green arrows) by prying up. Lever the clip up until it reaches the stop (yellow arrow).

Then remove the upper hose from the coolant expansion tank by pulling it straight off.
Figure 4

Then remove the upper hose from the coolant expansion tank by pulling it straight off. You may have to wiggle the hose a bit to get it to move free. Be careful not to damage the hose or tank. Both are made of plastic.

There is one hose remaining (yellow arrow) located at the bottom of the tank.
Figure 5

There is one hose remaining (yellow arrow) located at the bottom of the tank. I like to wait until I can lift the tank to remove this one. Start by removing the two T25 Torx fasteners (green arrows).

Working at the bottom of the coolant expansion tank, using a flathead screwdriver, release the hose retaining clip (green arrow) by prying up.
Figure 6

Working at the bottom of the coolant expansion tank, using a flathead screwdriver, release the hose retaining clip (green arrow) by prying up. Then pull the coolant hose off the coolant expansion tank. You may have to wiggle the hose a bit to get it to move free. Be careful not to damage the hose or tank. Both are made of plastic. Lift the expansion tank up to detach it from the rubber mounting grommet. Working at the bottom of the coolant expansion tank, disconnect the electrical connector by pressing the release tab and pulling it off (yellow arrow).

If your new expansion tank does not come with a level sensor (green arrow), you will have to transfer it over.
Figure 7

If your new expansion tank does not come with a level sensor (green arrow), you will have to transfer it over. Rotate the sensor 45 degrees clockwise. Then pull the sensor straight out of the tank. When installing the expansion tank, connect the coolant level sensor electrical connector. Next, connect the lower hose to the expansion tank. The retaining clip is properly seated when an audible click is heard. Connect the upper hose and engage the retaining clips until an audible click is heard. Then install the fasteners and reroute the hoses as they were before. Fill and bleed the cooling system. Once complete, double check all the hose connections and check the engine for coolant leaks.

If you have a check coolant level message and your coolant level is OK, you may have a faulty level sensor or wiring.
Figure 8

If you have a check coolant level message and your coolant level is OK, you may have a faulty level sensor or wiring. The sensor is activated by the float in the tank. A magnet on the float closes a small switch (green arrow). To check the circuit, start by disconnecting the electrical connector. Then jump the two terminals together. When jumped, the coolant message should go out. This would indicate a faulty sensor. If the message does not go out see the following step. Be sure the expansion tank level float is not stuck. If it is, it may not activate the sensor when the coolant level is full.

If you jumped the connector and the check coolant level message does not go away, check the wiring from the sensor to the lighting control module.
Figure 9

If you jumped the connector and the check coolant level message does not go away, check the wiring from the sensor to the lighting control module. You will want to grab a repair manual with the wiring for your specific model. The brown wire should be close to zero volts (0.1 volts). This wire is the ground. The brown wire with colored tracer (may vary) should be about 10 volts. If the ground is not present, try adding a ground to see if that remedies the issue. If the signal reference voltage is not present, you will have to run a new wire to the module or check for voltage out of the module.

Comments and Suggestions:
Wendell Comments: I have to replace a small hairline crack in my exspansion tank on my 2008 bmw 528xi. Mechanic said parts labor around 270.. but recommends me changing every thing up to 12-16kbecause the other plastic parts in system ie..hoses or radiator are sure to go bad immediately after replacement. .has this happened to any one yet here?
December 4, 2017
  Followup from the Pelican Staff: I always suggest replacing hoses and other plastic cooling system items when one goes. They are all the same age and can be close to failure as well. - Nick at Pelican Parts  
Mike Comments: I have a 2007 530 XIT. The bobber in the reservoir/expansion tank has come lose. Don't see anything that looks broken. Can you tell me how to re-affix on top of the float
November 29, 2017
  Followup from the Pelican Staff: it has to be replaced. Give The Pelican Parts parts specialists a call at 1-888-280-7799. They can figure out what part or repair kit you need.
- Nick at Pelican Parts
 
Eric Comments: I have a 2005 523I e60 and replaced a new coolant expansion tank 2 wks before. A faulty message of low coolant level light on yesterday, so I instantly checked the level of exp. tank, there was leak on bottom and some steam spilled from the cap. I am sure no leaking from hose joints.After the engine cool down, I found no more coolant inside the tank. I did all the procedures when installing like coolant level, bleeding around 8 to 10 mins. I guess some air still stuck inside or the tank was broken. Pls help.
October 1, 2017
  Followup from the Pelican Staff: I would pressure test the cooling system to see if the new tank is defective. - Nick at Pelican Parts  
VINCE Comments: I HAVE A 2012 BMW 528I XDRIVE THEIR ARE NO ILLISTRATION FOR MY PART.BMW 17-13-8-614-293 EXPANSION TANK W/LEVEL SENSOR
September 5, 2017
  Followup from the Pelican Staff: Give The Pelican Parts parts specialists a call at 1-888-280-7799. They can figure out what part or repair kit you need.
- Nick at Pelican Parts
 
LJM Comments: Hi There, I'm having trouble removing the lower hose on my 2009 coolant tank as wiggling it isn't working out so well, any suggestions on something else I could do or try for getting it off?

Thank you
July 25, 2017
  Followup from the Pelican Staff: if the clip came off fine and stay in the unclipped position, try cleaning and lubricating the hose area. Then pull straight off. They can be tough. - Nick at Pelican Parts  
Slim Comments: I have a 525i e60 the vehicle seems to be running in two gears only this can be seen from the rev counter, it is going as far as 6000 revs for a speed of 120km/h.Consequently the engine is overheating the display says Transmission fault and the engine check light is on.
I need help.
June 30, 2017
  Followup from the Pelican Staff: First check the transmission fluid level to be sure it is correct. Then check the transmission ECM for fault codes. If the system is not working properly, a fault code will be set. This will be your best bet when diagnosing.
- Nick at Pelican Parts
 
Mo Comments: Hey, I have a 2006 530i, after I replaced the reservoir it and filled up the tank, after I started driving it gave me another low coolant problem warning. Went home and filled up again only to have coolant leak out one of the valves on the tank that doesn’t have a hose connected to it
June 20, 2017
  Followup from the Pelican Staff: That is a cap. Some models do not use a hose there. Check if the cap seal is missing. - Nick at Pelican Parts  
Wiggles Comments: I have replaced the expansion tank on my E60 530i with a genuine BMW part and coolant. I filled the tank fitted the screw cap and ran the engine. Is it normal for fluid to be released from what I assume is an overflow on the top of the tank? As there is a considerable amount being released. Have I just overfilled the tank or is there a problem
April 16, 2016
  Followup from the Pelican Staff: Use the instructions in our coolant draining filling article. The steps there for filling are noted, you will be able to tell if you over-filled it. If you did not, the vehicle may have air trapped in the cooling system or be overheating. - Nick at Pelican Parts  
Muussaah Comments: Hi I have a 2004 e60 530i with the m54 engine same as e39 and low coolant level light come on due to it being low, filled it with bmw's antifreeze and 2 weeks later same again! After a 5 minute drive I put my hand below the expansion tank and there was a leak/couple drips... Now can anyone tell me if this is some sort of overflow hole or is it not supposed to drip from the bottom? Thanks
October 18, 2015
  Followup from the Pelican Staff: You may have spilled some. I would clean up spill, then run engine and recheck for signs of fresh coolant. - Nick at Pelican Parts  
DG Comments: Hi, I have a 2004 525i, have just installed a new expansion tank as the last one split down the side pretty sure the coolant was overfilled. Now, as soon as i start the car coolant leaks from the port just to the rear of the filler cap. Is this due to a faulty tank? Any suggestions? Cheers
July 12, 2015
  Followup from the Pelican Staff: No, your vehicle may require a plug for that port. Check if your old tank had one you can transfer over. - Nick at Pelican Parts  
Nate Comments: It's not stuck this thing is driving me crazy, something so small cause this big of a problem
July 9, 2015
  Followup from the Pelican Staff: I understand. Sometimes it's the little things that snag an easy repair. - Nick at Pelican Parts  
nate Comments: I have a 2006 5series 530i and the system reads low coolant but the coolant is full. and the coolant tank, waterpump, thermostat replace by bmw. still low coolant like comes on.
July 7, 2015
  Followup from the Pelican Staff: Check if the coolant level sensor in the reservoir is stuck. Could be dirty, causing it to stay in the low position. - Nick at Pelican Parts  
nate Comments: I have a 2006 bmw and the system reads low coolant but the coolant is full. and the coolant tank, waterpump, thermostat replace by bmw. still low coolant like comes on.
July 7, 2015
  Followup from the Pelican Staff: Check if the coolant level sensor in the reservoir is stuck. Could be dirty, causing it to stay in the low position. - Nick at Pelican Parts  

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Page last updated: Sun 12/17/2017 02:22:56 AM