Original thread- https://www.lotustalk.com/forums/f101...coolant-81698/
Today I spent the entire afternoon attempting to get as much of the sludge and Havoline XLC out of the cooling system as possible. The process of flushing out the system isn't too hard, but it is time consuming. Before I put the radiator hoses back onto the coolant tubes under the nose of the car, I took my garden gose with a spray nozzle, shot water down both tubes and allowed it to pour back out into the buckets I still have strapped to the front sway bar. This removed a lot of the crud in the tubes so I then used the the hose to flush out the radiator by fitting the end of the spray nozzle into one of the radiator hose ends and I collected the water as it came out of the other hose. This too cleaned out a lot of sludge. Here are a couple of photos showing the buckets under the hoses that need to be disconnected as well as the block drain.
Now for the fun part of filling the system to flush out the residual coolant in the heater core, tubes and hoses. I pushed the radiator hoses back onto the coolant tubes but did not install the clamps. I made sure the block drain was closed and then started pouring straight distilled water into the expansion tank. You have to be patient and take your time when filling the system because it takes a long time to purge the air trapped in it. Once you have the first gallon poured in, open the bleeder for the radiator in the right wheel well. You will need to remove the right front wheel and the fender liner to access this bleeder. The bleeder is in the top curve of the radiator hose as shown in this photo.
I also opened the bleeder in the return hose for the heater core which is located in the engine compartment as shown in this photo.
Now, I kept slowly pouring in more water until it started escaping out of the heater hose bleeder and then closed that bleeder. Again I kept slowly pouring in more water until I could hear it draining out of the bleeder for the radiator so I closed that one. I topped up the header tank again, started the engine, and held it at a fast idle with my hand on the throttle in the engine bay. This is easy to do with an '05 Elise because it has the cable operated throttle so if you are doing this on one of the newer cars, you will need an assistant to sit in the drivers seat to hold the throttle at a fast idle. Now, while keeping an eye on the temperature display, I poured in more water as the engine warmed up and the trapped air started burping out of the header tank. Once the temperature was over 190 degrees, I opened the heater hose bleeder and released as much air as possible, closed the bleeder and then moved to the radiator hose bleeder and did the same. A quick check of the header tank showed it was empty again, so I added more water to it. I kept doing this over and over again until there was no more air escaping from either bleeder and the header tank stayed full. It was also very important to watch the engine temperature display because at one point it reached 210 degrees and I could hear the water boiling in the engine block. I shut off the engine and kept slowly feeding it more water until The temperature came down to 180 degrees and then I restarted the engine. Eventually the temperature stabilized at 194 degrees and the system was not taking any more water. I then turned on the heater to make sure it was working and it was so I knew the entire system was purged of air.
Now, I drained the system as before by removing the radiator hoses from the coolant pipes and opening up the block drain. In the next post I'll show you the results of this flush.