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Proper maintenance of your coolant will go a long way towards extending the life of your radiator. The cooling systems on most cars are often very neglected, as most owners don't know much about them. See the Pelican Technical Article on Cooling System Flush & FAQ for more information. The most vulnerable components in the entire system are the radiator and the heater core, as they tend to be damaged by corrosion and electrolysis. Poor maintenance of the system can result in the build-up of corrosion elements in both the radiator and heater core, creating clogs and leaks that decrease cooling performance. If the engine overheats, the additional heat from the coolant can also damage sensitive plastic attachments and components.
When replacing your radiator, you want to make sure that you replace it with one that meets or exceeds the OEM cooling standards. BMW cooling systems are infamous for overheating problems. Therefore, it may be a wise idea to install an aftermarket performance radiator that performs a better job of cooling than the standard OEM one. I also recommend replacing your water pump, radiator hoses, thermostat, and any hose clamps too. All of these components can be damaged by a cooling system that has overheated. It's also a good time to swap out your old belts.
Okay, the first step in replacing your radiator is to remove all of the coolant from the system. See the Pelican Technical Article on Cooling System Flush & FAQ for more information. Now, we need to gain access to the radiator. Remove the front plastic panel that covers the front inside part of the engine compartment (Figure 1). Four screws hold this panel to the car. Now, it's time to remove your cooling fan. You will need a 32mm wrench, and a special fan removal tool (Figure 2). Unfortunately, I have not found an easy method of removal that does not require the use of this tool. The tool holds the two pulley nuts enabling you to remove the fan pulley nut (Figure 3). Holding the fan pulley steady with the tool, twist and remove the fan nut (Figure 4 and Figure 5). It is important to note that this nut has reverse threads, and needs to be turned clockwise to loosen it (Figure 6).
Now, you need to remove the fan frame with the integrated reservoir. The cooling fan housing frame is held in with small plastic rivets (Figure 7). Pop these out to loosen the frame from the radiator (Figure 8). You will have to disconnect the overflow hose prior to removing this frame (Figure 9). Also attached to the frame is the reservoir overflow hose. This hose winds around to the left side of the car, and needs to be disconnected near the power steering pump (Figure 10). This hose is shown disconnected in Figure 11. Now, disconnect the coolant level sensor (Figure 12). With all of these hoses and connectors disconnected, you should be able to remove the fan frame / reservoir from the car (Figure 13).
With the frame out of the way, now disconnect all of the hoses that are linked to the radiator. There are two large hoses, one on the top left side of the car, and one on the lower right. Loosen the hose clamp on the top left hose (Figure 14), and then pull it away from the thermostat housing (Figure 15). Figure 16 shows both sides of this hose. Now, disconnect the lower radiator hose on the right (Figure 17). Then, remove the electrical connector for the radiator temperature sensor (Figure 18).
With the hoses disconnected, now disconnect the automatic transmission lines, if you have an automatic transmission in your car (Figure 19). See the Pelican Technical Article, Replacing Automatic Transmission Lines for more details.
The radiator is held onto the chassis of the car with odd, complicated plastic clips. These are very difficult to remove, and you may end up breaking them when getting the old radiator out (Figure 20 and Figure 21). Using a screwdriver in the center of the clip, pry it out from the chassis and the radiator. You may have to play with these clips for a short while to remove them. With the clips removed, the radiator should no longer be attached to the car (Figure 22), and can be easily lifted up and out of the engine compartment. Figure 23 shows the radiator removed from the car. The small radiator attached to the center of the main radiator is the automatic transmission cooler. Make sure that you have a catch bucket (kitty litter boxes work very well) to capture all of the excess coolant and automatic transmission fluid that will spill out (Figure 24).
Figure 25 shows what the engine compartment looks like with the radiator removed. When you install your new radiator, or reinstall your old one, make sure that it sits firmly on the rubber mounts attached to the chassis (Figure 26). It is possible to install it slightly cocked if you don't pay attention to these mounts. Figure 27 and Figure 28 show the radiator reinstalled in the car. If you damaged your plastic clips removing the radiator, be sure to replace them with new ones. Reattach all of the hoses and connections. Use new hoses on the large upper and lower radiator hoses. If your clamps look worn, then replace them while you're in there too. Only use clamps specifically designed for large rubber hoses - some generic hose clamps can cause chaffing on the rubber when tightened. Then button up the front cover (Figure 29). Replace all of the coolant and bleed the system according to the the Pelican Technical Article on Cooling System Flush & FAQ.
Well, there you have it - it's really not too difficult at all. If you would like to see more technical articles like this one, please continue to support Pelican Parts with all your parts needs. If you like what you see here, then please visit our online BMW catalog and help support the collection and creating of new and informative technical articles like this one. Your continued support directly affects the expansion and existence of this site and technical articles like this one. As always, if you have any questions or comments about this helpful article, please drop us a line.
Peter Pesce adds:
Thanks for the great articles and tips, keep them coming.
One comment on your "BMW Radiator Replacement" article: You do NOT need to remove the cooling fan or shroud/frame to replace the radiator in an E36 coupe (1993 325is in my case). I just replaced mine this weekend, and had no problem getting the old one out and the new one in. It took me a couple hours, doing it outside in the driveway in 40 deg weather.
It would be good to note this in your article, as the plastic necks on E36 radiators are a common failure point (mine failed there) so a lot of people are doing this particular job, by choice or necessity! You might also note that you can swap out the main upper and lower radiator hoses with the fan and frame in place as well.
Thanks, and keep up the good work.
New York. NY