Bmw e39 5-series thermostat replacement 1997-2003 525i, 528i, 530i, 540i pelican parts diy maintenance article electricity outage austin


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.

Comments: 2001 BMW E39 540. I have just recently replaced my Aux Fan and Coolant temp sensor and im still having an issue where the fan is constantly running and im still getting IPNA error code 125 temp sensor outlet, temp alot low. i went to have a look at the parameters, i noticed the the coolant outlet temp reads 90 degrees regardless if the engine is cold or hot. Anyone else have any pearls of wisdom for me?

Comments: I own a 1997 bmw 528i. My car takes a while to overheat and when it does, im usually at a stop light. And when it overheats i have to push the gas pedal to the floor just to get up to thirty to get home. My father suspects it to be a blown head gasket because of light brown oil and loss of power. Any suggestions?

Followup from the Pelican Staff: That code is related to secondary air fault. You’ll want to run a system test using an advanced scan tool like autologic, to see if the secondary air pump runs, and if flow is detected. You can also confirm if the pump runs by listening for it at a cold start. – Nick at Pelican Parts

Comments: I have a bmw 530i, we have replaced the thermostat 3 times in 2 years and now getting ready to replace again in less than 4 months. Do these thermostat wear out that quickly or is it a faulty item I keep replacing. FYI, when we replace the thermostat it solves the overheating. The car is great other than I can’t go far for fear the car will overheat.

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

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.

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

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?

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

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

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.