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Flushing out the old coolant

Original thread- http://www.lotustalk.com/forums/f101/changing-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.

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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.

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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.

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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.
 

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Here is a photo showing the drained distilled water and flushed out coolant from the two flushes I did this afternoon.

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The first flush is the bucket with the orange/brown colored silty water in it. The second flush is in the other bucket and it has almost no orange color in it so I think it is safe to assume there is not much Havoline left in my cooling system. The water in the second bucket is still silted and not clear so I am going to have give the system yet again another flush. :( That will have to wait for another day though as I am out of time for today.
 

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I forgot to add something about the bleeders. Both of the bleeders shown in the photos use a small O-ring under the thumbscrew cap for a seal. If you open the bleeders too far and the screw falls out, this O-ring stays with the bleeder body and will be washed away with the expelled coolant. I managed to lose one of mine because of this (it is somewhere in the front structure of the car) and I had to get a replacement. The photo below shows the correct size description from the package and one of the O-rings I purchased at Home Depot from their plumbing department.

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As of today, I have successfully changed the coolant in my Elise. The third flush with distilled water did the trick and yielded a bucket of clear, colorless water when the system was drained. I refit the radiator hoses to the coolant tubes and clamped them in place as well as closed the block drain and removed my drain hose. Next, I poured in one gallon of 100% straight coolant to offset the 3 quarts of residual distilled water trapped in the system (I added one extra quart just to be sure I would have a 50% or higher coolant mix). This took quite some time to accomplish as straight coolant is thicker than water and I could only pour in small amounts at a time. I then switched to 50/50 coolant and distilled water to top up the system as much as possible until the bleeders flowed only coolant and no air. I started the engine and ran it at high idle (2,000 rpm) while watching the temperature display. When the temperature reached 190 degrees I opened the bleeders again to remove the last of the air and the system stabilized at 188 degrees (it is cold here in WI now so the radiator fans never turned on). I shut off the engine, topped off the header tank one more time, and I was done.

Now, for the big question. What did I use for coolant? Well, it wasn't the coolant as recommended by RoadDad :p but rather the Prestone Extended Life I mentioned earlier so my car now has yellow/green coolant in it. I will keep everyone updated on how well this coolant works as well as if there are any compatibility or corrosion issues (I still have my test jar of Havoline mixed with Prestone and a piece of aluminum in it). Prestone says their coolant is good for 5 years or 150,000 miles, but I intend to change it after only 2 years just to make sure there are no issues with it. Wish me luck!
 
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