How to bleed cooling system BMW 525i


BMW recommends to its users that you need to have your car’s engine coolant to be replaced at least once every two or four years depending on how much you use it. You will need to understand more about it depending on the type of coolant that you normally use. If you only drain the coolant out of the system of your car, there might be some coolant left in there. There is this so-called block drain that is a plug that you can open to drain out the coolant that is in your black. Once you replace your water pump, you should also be able to drain some of the coolants. You need to know how to bleed cooling system BMW 525i and there are some things that you might want to consider in doing just that. 

BMW Cooling


Draining your coolant

The first thing that you will need to do would be to drain your coolant. There are some steps that you will need to follow to achieve this. For instance, you will need to remove the drain plug that should be found at the base of your radiator. This is around 17 mm and you will need it so you can drain your coolant onto your drain pad. Most of the engines out here will have a 13mm drain blog so you will just need to see which one is yours. Make sure that you have your drain pad ready before you unplug it and drain it out. This would help you out so that you would not have to clean up any messes later on.

Filling and bleeding

After you are done with draining, the next thing to do would be to fill and bleed. What you need to do would be to open your bleed screw that is inside your thermostat housing. Be careful not to remove it completely as that is not what you want. In case you have an eight-cylinder engine, then the bleed screw should be found on the filler neck that is near the expansion tank. This can also be located on the right side of your radiator. Once you have opened it slightly, the next thing to do would be to let your coolant into the expansion tank. Do this as slowly as you possibly can. This is an important part of how to bleed cooling system BMW 525i. Fill up your cooling system until your fluid would come out of your bleed screw which is in the thermostat housing. Once you have done it, let it stand for a few minutes. Then, add in some coolant again before you close your bleed screw. Make sure not to over tighten it but to just tighten it enough. In case you happen to have an eight-cylinder then you will need to open the bleed screen that will be located on your expansion tank and fill that up with coolant until it bleeds on the expansion tank. 

Start your engine

Once you have closed the screw, the next step would be to start your engine and set up your heater controls to their maximum possible heat level. Do not forget to turn your fan too high as well. Let your car run until your thermostat opens and your lower radiator hose will start to get hot. After this, let your engine cool off and then repeat the previous steps on filling and bleeding. If you are using an eight-cylinder, then you need to repeat the process only until your coolant flows out of your bleed screw. When you are done, you should have your temperature gauge to stay on the halfway mark of your gauge.


Finding the right coolant for your car can be a little complicated because there are a lot of different types of it. However, you must note that an effective coolant can keep your engine from overheating as well as freezing. It should also help to protect your engine from any possible corrosive elements and help improve the performance of your car. So what are the components of an effective coolant? The first one would be water. Water should be what makes up half of the coolant and antifreeze mixed with water is what makes a coolant in general. You can easily opt to DIY your coolant but if you want prime performance, purchasing pre-mixed ones would be better for sure. Regarding how to bleed cooling system BMW 525i, you will probably be better off if you buy a ready-to-use one. 

Other coolant ingredients

Other ingredients of the coolant would include ethylene glycol which is the main active ingredient of most coolants out there. It is a chemical that is mostly responsible for the liquid in your car to circulate so that it does not freeze when the temperature is cold and would not let it evaporate even during extreme heat. Another would be propylene glycol and which is one of the good alternatives for ethylene glycol and it has a higher viscosity and is more efficient in transferring heat. It is also considered to be less toxic which is one of its major selling points. Besides those and water, some corrosion inhibitors are mixed with coolants. This is to make sure that they would also help out in preventing any possible corrosion inside of your engine. 

IAT or Inorganic additive technology

This type of engine coolant is known to be green in color and it is made using silicate, ethylene glycol, and phosphates that help to prevent any possible corrosion. It is mostly used on older vehicles such as cars that have been manufactured in the US way before the 1990s. it is an older formula so you can expect that it would not work as well as the new ones. However, if your car is an older version, then you might want to consider it.

OAT or Organic acid technology

When it comes to learning how to bleed the cooling system BMW 525i, the coolant is necessary. Another type of coolant would be the OAT or the organic acid technology coolant and it is normally orange in color although it can also come in colors such as dark green. It is made using propylene glycol as its base. Make sure that you are going to check the label so that you would not accidentally grab the wrong coolant type. This is normally compatible with Saab and VW cars.

Phosphate-free HOAT

Phosphate-free hybrid organic acid technology coolant has a unique turquoise color. It is NAP-free and is made using ethylene glycol as the base. It has both inorganic and organic corrosion inhibitors so that it fully protects your engine. It does not have any phosphates like nitrate well as borate. It is also low in silicate and can be used with a lot of different car brands. BMW, Rolls-Royce, Volkswagen are some of the many cars that prefer this coolant so you need to take note of this. The first step that you need on how to bleed cooling system BMW 525i would be to find the right coolant for you so you should consider this when you are buying one. 

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