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N52 Engine Thermostat Replacement
 
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Pelican Technical Article:

N52 Engine Thermostat Replacement

Nick Czerula

Time:

3 hours3 hrs

Tab:

$300

Talent:

*****

Tools:

Set of sockets, wrenches, screwdrivers,

Applicable Models:

BMW X3 Sport Utility (2007-10)

Parts Required:

Thermostat, hoses, engine coolant

Hot Tip:

Work with a cool engine.

Performance Gain:

Car will cool down again and fault code will go away

Complementary Modification:

Flush cooling system

BMW E83X3 models with an N52 engine utilize an electrically-heated engine thermostat. The thermostat is integrated with the thermostat housing; the two are replaced as a unit. The thermostat is mounted to the right side of the engine at the lower front, near the air conditioning compressor. The DME (engine control module) controls and monitors operation of the thermostat. If a fault occurs a code is stored in the DME, usually with a description of "Map cooling circuit". A fault code can be present yet the vehicle will lack any cooling system issues, such as overheating. This can be a tough part to change as it is tucked away and behind many components. I like to remove the radiator cooling fan when I have to replace a thermostat, it makes access a lot easier. Working from just below can be a real pain.

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 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. Questions or want to add to the article? Leave a comment below. When leaving a comment, please leave your vehicle information.

This can be a tough part to change as it is tucked away and behind many components.
Figure 1

This can be a tough part to change as it is tucked away and behind many components. I like to remove the radiator cooling fan when I have to replace a thermostat, it makes access a lot easier. Working from just below can be a real pain.

The red arrow points to where on the engine the thermostat is located.
Figure 2

The red arrow points to where on the engine the thermostat is located.

Remove engine splash shield.
Figure 3

Remove engine splash shield. See our tech article on splash shield removing. Drain cooling system. See our tech article on cooling system draining and filling. Remove the radiator cooling fan (red arrow). See our tech article on radiator cooling fan removing.

Once the fan is out, you have access to the thermostat (red arrow).
Figure 4

Once the fan is out, you have access to the thermostat (red arrow). Located just below the air condition compressor, pulley shown. When removing the first two hoses, you will work from above, through the space the radiator fan was in.

Next you have to remove the front hose connected to the thermostat.
Figure 5

Next you have to remove the front hose connected to the thermostat. It is right above the subframe and right side of sway bar. Using a flathead screwdriver, release the thermostat hose retaining clip by prying up (red arrow). The hose clip will stop at the unlocked position. I suggest leaving it installed on the hose so you don't lose it.

Then, follow the hose to the radiator and release the thermostat hose retaining clip by prying up (red arrow).
Figure 6

Then, follow the hose to the radiator and release the thermostat hose retaining clip by prying up (red arrow).

Once the clip is released, remove the hose from the radiator.
Figure 7

Once the clip is released, remove the hose from the radiator. You may have to wiggle the hose a bit to get it to move free. Be careful not to damage the radiator, it is made of plastic. If needed, gently lever on the hose (red arrow).

Then disconnect the hose at the thermostat connection.
Figure 8

Then disconnect the hose at the thermostat connection. Remove the hose from the engine. Be prepared to catch any excess dripping coolant in a pan.

Next you will have to remove the small hose at the side of the thermostat (red arrow).
Figure 9

Next you will have to remove the small hose at the side of the thermostat (red arrow). Using a flathead screwdriver, release the thermostat hose retaining clip by prying up. Remove the hose from the thermostat. You may have to wiggle the hose a bit to get it to move free.

Working at the bottom of the thermostat.
Figure 10

Working at the bottom of the thermostat. Use a small pick (inset), release the electrical connector (red arrow) and remove it.

Now it's time to remove the last two hoses.
Figure 11

Now it's time to remove the last two hoses. Working from below on the right side of the subframe. First loosen the hose clamps at the rear hoses (red arrows). Then remove the hoses from the thermostat. Be prepared to catch any excess dripping coolant in a pan.

Still working from below.
Figure 12

Still working from below. With all the hoses disconnected, remove the two 10mm thermostat mounting fasteners (red arrows). Use a long extension and a universal 10mm socket.

Then remove the thermostat from the front, over the subframe (red arrow).
Figure 13

Then remove the thermostat from the front, over the subframe (red arrow). Be prepared to catch any excess dripping coolant in a pan. If any hoses were left connected like on my subject vehicle, remove them now that you have better access.

Still working from below, slide the thermostat (red arrow) over to the left side of the subframe (blue arrow) and leave it there, to be removed from above.
Figure 14

Still working from below, slide the thermostat (red arrow) over to the left side of the subframe (blue arrow) and leave it there, to be removed from above.

Working from above, remove the old thermostat.
Figure 15

Working from above, remove the old thermostat.

Install new thermostat and evenly tighten fasteners.
Figure 16

Install new thermostat and evenly tighten fasteners. Install coolant hoses, listen for an audible click to confirm that clips have engaged. A small amount of new coolant can be used to lubricate coolant hose O-rings, this will make installing hose easier. Connect thermostat electrical connector. Install radiator and cooling fan. Install splash shields and fill and bleed cooling system. Remember to check the cooling system for leaks and top up coolant when complete. When bleeding, expect a steady stream (red arrow) to flow from the bleed hole in the reservoir. Turn ignition ON (do not start engine), set temperature controls in vehicle interior to full warm and blower fan speed to Low. Press accelerator pedal to floor and hold down for ten seconds. Electric coolant pump will run for about 12 minutes (cycling on and off) to circulate coolant and bleed air from cooling system. Once pump has run the cycle, check level of coolant in expansion tank and adjust as needed. Start and run engine at idle until it reaches operating temperature and check cooling system for leaks. This stream will start and stop as the water pump cycles during the bleeding process.

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Page last updated: Sat 4/29/2017 03:18:02 AM