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Thread: How to/DIY: Flush Coolant

  1. #1

    Default How to/DIY: Flush Coolant

    This is an easy one Â*I pulled up onto some ramps to allow more room underneath. Â*From under the car, remove the passenger side corner of the undertray (I think it's only five clips). Â*This will expose the radiator drain and plug. Â*Remove the radiator cap (as long as the engine temperature is cool) and grab a drain bucket. Â*Loosen the 10mm plug (circled in red, arrow points to front of car) until there's a steady flow of fluid coming out of the radiator:

    Don't take the plug completely out until the flow is almost stopped:


    Remove the cap from the overflow reservoir and undo the two 10mm bolts holding it down:


    Dump the contents out and rinse out the junk that's settled at the bottom:


    Reinstall the reservoir and torque to 44 +/- 9 in-lbs. Â*You can also refill it to somewhere between the Min and Max lines with your desired ratio of coolant/water (see end) and replace the cap.

    If you're doing your thermostat (now's really a good time), you'll want to remove a portion of your upper intercooler pipe to expose the housing:


    Undo the three 10mm bolts and pull up on the upper radiator hose/thermostat housing:


    Pull the old thermostat out and replace it with the new one (pay attention to its orientation). Â*Clean both sides of the housing and keep them free of coolant. Â*Put a bead of Ultra Gray RTV around the upper housing and reinstall bolts (84 +/- 13 in-lbs). Â*Reinstall the intercooler piping and clamps (53 +/- 9 in-lbs).

    The service manual also states to remove the drain plug from the block. Â*I found the plug (you'll need an 8mm allen head to remove it), but getting to it with just your hand is very difficult and I highly doubt getting tools back there is feasible without removing several other items (battery, etc...). Â*This would be an approximate view from the firewall, but without various wires, vacuum lines, etc... in the way:


    I did not remove this plug as I was able to extract about 5 of the 6 quarts of old coolant out of the system. Â*If you do remove this plug, you'll want to use Loctite Blue 242 and torque it to 33 +/- 3 ft-lbs. Â*You could also take off the lines going to the turbo, throttle body and heater core, but I chose not to.

    Once all the coolant has been drained, replace the radiator plug and tighten it until snug. Â*If you've replaced the thermostat, let the RTV cure for about an hour. Â*Otherwise, it's time to add the coolant mix to the radiator. Â*The manual calls for anywhere from a 30%-60% concentration of coolant/antifreeze. Â*Remember to use distilled/deionized water (avoid mineral, spring, drinking and (especially) tap water). Â*I went with a 25% mixture and a bottle of Water Wetter.

    Once the system is "full" replace the cap, start the car and let it warm up. Â*Rev the engine or go for a short drive and let it cool. Â*Remove the cap when safe and top off the coolant level. Â*It's also a good idea to make sure you've got heat and that your engine temp isn't climbing above normal (aka the halfway point on the stock gauge). Â*If you aren't holding a normal temp and/or have no heat, there may be a pocket of air in the system which should work itself out.

    Repeat every 30K miles according to the manual. Â*If you're using Water Wetter like me, you'll want to change it more often as it tends to break down sooner than that.

  2. #2
    vtluu Guest

    Default General Maintenance: Coolant

    Replaced the coolant yesterday and thanks partly to your instructions, it was a cinch. The only thing I would add is that it's useful to connect a hose to the drain; until I did that some of the coolant would drip onto the underbody cover and spill out at different places. The little bit of hose feeding into the drain bucket keeps things a lot tidier.

  3. #3

    Default General Maintenance: Coolant

    Good call

  4. #4

    Default General Maintenance: Coolant

    wow, that was a very thorough write-up J! nice pics too. thanx for the info.
    Using No Way as Way, Having No Limitation as Limitation

  5. #5
    Join Date
    Mar 2005
    Posts
    7,824

    Default Re: General Maintenance: Coolant

    Quote Originally Posted by thomas
    wow, that was a very thorough write-up J! nice pics too. thanx for the info.
    Just doing a little searching around before I install my 42DD thermostat housing for my coolant temp sender. I wonder where the pics went? Probably don't need them since it sounds pretty easy, but it still would be cool to see them.

  6. #6
    vtluu Guest

    Default Re: General Maintenance: Coolant

    I replaced the thermostat. Piece of cake.

  7. #7
    Join Date
    Mar 2005
    Posts
    7,824

    Default Re: General Maintenance: Coolant

    Quote Originally Posted by vtluu
    I replaced the thermostat. Piece of cake.
    But you still have to go through the whole draining process, yeah?

  8. #8
    vtluu Guest

    Default Re: General Maintenance: Coolant

    I guess in theory you could just drain the coolant until it's below the level of the thermostat. But it's zero effort to drain more coolant.

  9. #9

    Default Re: General Maintenance: Coolant

    I would just drain it all. Might as well change your coolant too.
    Jeremy<br />Mitsubishi Master Technician<br />CCMW<br />

  10. #10

    Default Re: General Maintenance: Coolant

    HEY!! 500 posts, I am now a Canyon Racer!!
    Jeremy<br />Mitsubishi Master Technician<br />CCMW<br />

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