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BMW E39 Thermostat Removal
 
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Pelican Technical Article:

BMW E39 Thermostat Removal

Kerry Jonsson

Time:

3 hours3 hrs

Tab:

$100

Talent:

****

Tools:

Flat head screwdriver, 13mm socket and ratchet, 10mm swivel socket with extension and ratchet.

Applicable Models:

BMW 525i Sedan/Wagon (2001-03)
BMW 528i Sedan/Wagon (1997-00)
BMW 530i Sedan (2001-03)
BMW 540i Sedan/Wagon (1997-03)

Parts Required:

thermostat, lower coolant hose, coolant

Hot Tip:

Drain the cooling system from the radiator first

Performance Gain:

Fixes over-heating and low heater output

Complementary Modification:

Replace the drive belt and cooling fan at the same time

The job of the cooling system is not just to keep the engine cool. Its job is to regulate the engines temperature and keep it in the optimum range for the engine to operate. By keeping the engine is its operating temperature range the internal components of the engine will have expanded and formed proper seals such as the piston rings in the cylinder walls. This increases the efficiency of the engine and reduces oil consumption. This is achieved with a thermostat. The thermostat stays closed when the engine is cold to stop coolant flow and help increase the temperature of the engine quickly. As the temperature increases and needs to cool off the thermostat opens. The DME can energize a heating element in the thermostat and open it further to increase coolant flow. A thermostat can fail and stay stuck closed, causing over-heating, or open too soon and keep engine temperature too low. In this tech article we will go over all the steps to remove your thermostat so you can replace it.

On the six cylinder models you have more room to work if you remove the cooling fan and fan shroud. We have done this for photographic purposes. On eight cylinder models you do not have to remove the expansion tank but we have done so for photographic purposes.

You will need to remove the air intake duct and resonance chamber, please see our article on replacing your MAF sensor to preform this work.

You do not have to but you should remove the lower engine cover underneath the car. This gives you access to the radiator drain screw. This allows you to drain the cooling system with a minimum of coolant loss or mess.

Thermostat Removal on Eight Cylinder Model:

Working underneath the car on the left side of the radiator remove the 17mm drain plug (green arrow) and allow the coolant to drain into a drain pan.
Figure 1

Working underneath the car on the left side of the radiator remove the 17mm drain plug (green arrow) and allow the coolant to drain into a drain pan.

With the air intake duct and resonance chamber removed you can see the lower radiator hose (green arrow) which connects the radiator with the thermostat.
Figure 2

With the air intake duct and resonance chamber removed you can see the lower radiator hose (green arrow) which connects the radiator with the thermostat.

Working at the thermostat side of the lower radiator hose use a flat head screwdriver to loosen the clamp that secures the lower coolant hose with the thermostat.
Figure 3

Working at the thermostat side of the lower radiator hose use a flat head screwdriver to loosen the clamp that secures the lower coolant hose with the thermostat.

You can use a flat head screwdriver to push the thermostat electrical connector retaining clip (green arrow) in the direction of the blue arrow.
Figure 4

You can use a flat head screwdriver to push the thermostat electrical connector retaining clip (green arrow) in the direction of the blue arrow. You can then unplug the electrical connector by pulling it away from the thermostat.

Working with a close up view of the thermostat remove the four 10mm fasteners that secure the thermostat to the water pump.
Figure 5

Working with a close up view of the thermostat remove the four 10mm fasteners that secure the thermostat to the water pump. One fastener is hidden behind the thermostat hose connection. We have placed a swivel socket with extension and ratchet to illustrate approximately where the fastener is located. A swivel socket or wobble extension does make the job a lot easier.

The thermostat will probably be held in place in the water pump.
Figure 6

The thermostat will probably be held in place in the water pump. Pull the thermostat out of the water pump housing in the direction of the blue arrow. Installation is the reverse of the removal steps. Fit the thermostat in the housing and tighten the fasteners. Fit the coolant hose and tighten the clamp. Install any components you removed to gain access to the lower radiator hose. Follow the steps in the tech article on filling and bleeding your cooling system. 

Thermostat Removal on Six Cylinder Engines:
Working at the front of the engine loosen the two hose clamps (green arrows) that connect the thermostat housing to the upper and lower radiator hoses.
Figure 7

Working at the front of the engine loosen the two hose clamps (green arrows) that connect the thermostat housing to the upper and lower radiator hoses.

If you have the modern hose connections use a flat head screwdriver to lever up on the hose retaining clips.
Figure 8

If you have the modern hose connections use a flat head screwdriver to lever up on the hose retaining clips.

Looking at the thermostat remove the three 10mm fasteners and one 13mm fasteners (green arrows) that secure the thermostat to the engine.
Figure 9

Looking at the thermostat remove the three 10mm fasteners and one 13mm fasteners (green arrows) that secure the thermostat to the engine. You are also going to have to remove the engine lifting bracket (yellow arrow) before you can remove the thermostat.

On later models 1998 and later press in the retaining spring for the thermostat electrical connector and unplug it from the thermostat.
Figure 10

On later models 1998 and later press in the retaining spring for the thermostat electrical connector and unplug it from the thermostat.

Remove the 13mm fasteners (green arrow) to fully remove the engine lifting bracket.
Figure 11

Remove the 13mm fasteners (green arrow) to fully remove the engine lifting bracket. Now you can fully remove the thermostat.

With the thermostat housing removed clean the gasket surfaces to ensure a good seal when you refit the thermostat.
Figure 12

With the thermostat housing removed clean the gasket surfaces to ensure a good seal when you refit the thermostat. Installation is the reverse of the removal steps. Fit the thermostat and install the three 10mm mounting bolts. Install the engine lifting bracket and tighten the two 13mm fasteners along with the three 10mm fasteners on the thermostat. Install both cooling hoses and tighten the clamps. Refit any components you removed to get access to the thermostat. Follow the steps in our tech article on filling and bleeding your cooling system.

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Comments and Suggestions:
Frog Comments: I have recently bought an 01. 525i. Because the car had set up for over a year, we thought we should put some fuel injector cleaner in it. Well, we put C foam in it. Oh my god. It didnt smoke at all before this and now it wont stop. We are on the 6th tank full of premium and it still smokes. Just about ever time its cranked or excelerate from a full stop. We have changed fuel filter,spark plugs,changed oil and the PCV. Frustrated and out of options
November 13, 2016
  Followup from the Pelican Staff: Where did you put the sea foam? What color is the smoke? - Nick at Pelican Parts  
Robbie Comments: My BMW530i 2003 the front A/C heat regular is jammed and only cold air come not warm.
November 11, 2016
  Followup from the Pelican Staff: You'll need to gain access to the heater housing and check if the flap motor is jammed or the flap. We don't currently have that tech article. If we get a chance to perform the procedure, we will be sure to document it.


I would grab a repair manual. It will have the procedure, special tools and torque specs.


Give our parts specialists a call at 1-888-280-7799.- Nick at Pelican Parts
 
Taylorl Comments: I have a 1997 bmw 528i that only overheats when at idle. I changed the fan switch and it is still over heating
October 29, 2016
  Followup from the Pelican Staff: I would replace the thermostat. - Nick at Pelican Parts  
slappy Comments: i have a defrost that only works on high wind speed why
March 18, 2016
  Followup from the Pelican Staff: Blower motor final stage may be faulty. - Nick at Pelican Parts  
joe Comments: It sounds like no compression when I'm cranking it, but when it starts up there's no miss fire,engine running smooth.
January 7, 2016
  Followup from the Pelican Staff: OK, thanks. When your engine doesn’t start you’ll want to check the basics. Check spark, fuel injector pulse and fuel pressure, volume, quality and engine compression. Are there any fault codes? Once you figure out what is missing, it will be easier to diagnose. - Nick at Pelican Parts  
joe Comments: Thank you for the advice,I realy appreciate it,wil get back to you soon as I check it out,the engine also has a free swing when starting it up,but when it running no miss fire,it runs smooth,is there any possiblities of engine or head problem because the engine swinging free when starting up?
January 6, 2016
  Followup from the Pelican Staff: I don't understand what you mean by swinging free. - Nick at Pelican Parts  
joe Comments: Hi,my 97 e39 540i heats up and water start to buble up in the water bottle I tried bleeding the system but its still bubbles up in the water bottle,can it be the thermostat jamming up?
January 5, 2016
  Followup from the Pelican Staff: Could be the thermostat or a faulty water pump. Start by checking the coolant level. Then check if the thermostat opens once then engine reaches operating temp. If the thermostat doesn't open and coolant does not begin to flow, it is faulty. - Nick at Pelican Parts  
Braverman530i//M Comments: Hello! I have an 03 530i i6. Temp stays cool for most of dricing time until I stop, never goes higher.than middle. I'm guessing thermostat is open, needs replacing. Any ideas?

Thanks!
December 9, 2015
  Followup from the Pelican Staff: Sounds like a thermostat to me. I would replace it and the radiator hoses. Give our parts specialists a call at 1-888-280-7799. They can figure out what part or repair kit you need.
- Nick at Pelican Parts
 
brad Comments: sry 99 540i
September 20, 2015
  Followup from the Pelican Staff: Got it. - Nick at Pelican Parts  
brad Comments: hi does the rubber gasket in the lower hose that connects to the thermostat have to be replaced as well.
September 20, 2015
  Followup from the Pelican Staff: That sealing O-ring is part of the hose. Usually they leak when reinstalling, so replacing it is a good idea. - Nick at Pelican Parts  
Sroor9001 Comments: Hi friend how are you
My car 525 2002 the tempreture is raising so quickly toward 103 then go down it was before 99-100 is it normal ?? Or the thermostat stuck open ??
Cause even when it's cool it's raising so quickly aux fan start @ 91 C and mechanical fan work ok heard the noise and it cools fine
But want to know that sign of raising from 34 or so to 103 is it failing thermostat ??
May 21, 2015
  Followup from the Pelican Staff: It's hard to say. Is the engine temp actually changing that quickly? If so, it may be a problem. Check if the thermostat is jammed and confirm the coolant level is OK. - Nick at Pelican Parts  
kresearch Comments: The title says E3 5-Series. I have an E39/1998 and it is not integrated into the housing. It is a separate part. The article also does NOT cover re-assembly.
February 25, 2015
  Followup from the Pelican Staff: No defensive tone here, just relaying what info is being discussed. 8- and 6-cylinder engine are covered. Installation is reverse of removal, no need for steps as you reverse the steps you performed to remove it. Notes for 8-cylinder installation steps included here:
The thermostat will probably be held in place in the water pump. Pull the thermostat out of the water pump housing in the direction of the blue arrow. Installation is the reverse of the removal steps. Fit the thermostat in the housing and tighten the fasteners. Fit the coolant hose and tighten the clamp. Install any components you removed to gain access to the lower radiator hose. Follow the steps in the tech article on filling and bleeding your cooling system. Thermostat Removal on Six Cylinder Engines - Nick at Pelican Parts
 
kresearch Comments: Guys, I don't see much about the actual thermostat valve, how the new one is placed, o-ring installed, unit sealed back, and assembled. This must be part of the article, no?
February 24, 2015
  Followup from the Pelican Staff: The entire article is removing and replacing the thermostat. Give it a reread. It is integrated into the housing, as it the sealing O-ring. - Nick at Pelican Parts  
Frank Comments: Do I have to bleed my BMW 540i. New thermostat but I don't think is opening up
February 22, 2015
  Followup from the Pelican Staff: Yes, if you opened the cooling system you have to fill and bleed it. - Nick at Pelican Parts  
Mitch Comments: Currently it's running fine no Engine light running back to what it was before. ran it about 44Miles so far no Misfire. Its a 2004 525I.

Nick On replacing the Thermostat that I plan on doing tomorrow, do I also have to drain the Coolant from the Block or can I just drain some from the radiator ?
September 19, 2014
  Followup from the Pelican Staff: You can choose to drain just enough to get the the thermostat out. I have done that is the past when the coolant in the vehicle was fresh. - Nick at Pelican Parts  
Mitch Comments: Nick,
Is there a Such this as Driving Cycle for BMW'S ? Last knight I was missing around with INPA Software to check if something would indicate thermostat so the car was also on Empty with the gas indicator on, I decided to delete code from memory and I keep looking around in the INPA and then all the sudden the car started shaking hard and all light came on as Check engine and Tran I turned it off immediately, Turned the car back on same thing shaking Violently turned it off waited and then turned it back on and it was idling normal. Turned it back off and Erased Error Codes with my other tool. I Turned it back on and drive to the gas station with no problem at all no engine light and drove it today to work no problem. The only thing is that the CCT Reads Not Ready and the Vaper also not ready.
September 18, 2014
  Followup from the Pelican Staff: All OBD II cars use a drive cycle to reset the emission monitors. The later a vehicle is, the easier it is to perform. A lot of times, just driving the vehicle over a few days will reset it.

INPA is engineering software, be very careful when using it, most times I advise against. it. SOunds like your vehicle has a misfire. - Nick at Pelican Parts
 

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Page last updated: Mon 12/5/2016 02:05:34 AM