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Thread: How To: Draining coolant from Engine

  1. #1
    Senior Member mr_maxime's Avatar
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    How To: Draining coolant from Engine

    When I changed my coolant (first time doing this on any car) I thought draining the engine block would be simple, but it was in fact a gigantic mess. I think this method will help keep anyone from repeating my mistakes.

    I took the rear fascia off and noticed how much easier it is to see the drain plugs. These are the same square plug as the oil drain plug.

    Passenger side above oil filter

    Driver side hidden above the catalytic converter. Notice there is another plug, but this uses an allen head. Don't remove this one.

    These are both accessible underneath the car, but you'd be going in blind. When I did this, coolant started gushing out immediately covering me in coolant and you pretty much want a kiddie pool under the car to collect it all. It went absolutely everywhere, especially since it splashes onto the catalytic converter first. So, if you take the time to take the rear fascia off, you should be able to remove the plugs without having your face under the car and make it 100x easier to put the driver side plug back in.

    If anyone has any tips to controlling the flow to keep it from splashing everywhere, I'd also appreciate the tip. Otherwise I'm thinking of getting an EZ-drain valve so I can just hook up a hose to it.

  2. #2
    Administrator Ron's Avatar
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    Curious as to why not dump it from the lower radiator hose and run a good flush through it..?

  3. #3
    Senior Member mr_maxime's Avatar
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    I drained mine from the radiator when I was replacing it. While on the phone with DMCMW, they told me I might as well drain the engine since I had most of the coolant out. I also didnt have any equipment for flushing. I know the DMC support page recommends draining the engine if changing the water pump as well.

    Then again, not being that experienced, I wanted to at least show people where the drain plugs where and to avoid getting showered in coolant like I did.

  4. #4
    '82 T3 FABombjoy's Avatar
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    The plugs also have M16 copper crush washers which should be replaced if you remove them. If not replaced at least inspected for uniformity. Both of mine were pretty grooved so I changed 'em.

    One potential good thing about using the block plugs is that the coolant flow in and out of the heads is only at the top. Pulling the plugs gives you a chance to remove any crud that's collected at the bottom. Probably not much if it's baked in but it's better than nothing.

    With the water pump removed you could probably thread in some temporary M16x1.5 to hose barb fittings and power flush through the upper water pump attachments. Drop in some kind of magic aluminum-safe descaler, let it stew, then blast it out. That would be harder to do exclusively through the water pump feed/return lines.
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  5. #5
    Senior Member mr_maxime's Avatar
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    This is what I would like to change them to. Website says they can be used with coolant.

  6. #6
    Senior Member Josh's Avatar
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    you plan on changing your coolant that often? Doesn't really seem worth it. Also another point of many for the coolant system to leak. Unlike the oil pan the entire coolant system is under pressure...

  7. #7
    Senior Member mr_maxime's Avatar
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    Quote Originally Posted by Josh View Post
    Unlike the oil pan the entire coolant system is under pressure...
    I didnt consider that. I still have to replace the hoses and I'm assuming at some point the water pump will fail and have to be changed out as well.

  8. #8
    One of those purists you keep hearing about. sdg3205's Avatar
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    I think draining the block every time you change the coolant is a little overkill. The only time i cracked those block drains was when i was dealing with the head gaskets and didn't want coolant spilling into the cylinders and oil.

    I agree with Josh. Compatible or not, our cooling systems are large and complex enough as it is. Adding two more valves is probably not worth the risk.

    Here, somewhere.

  9. #9
    Member Delta DeLorean's Avatar
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    When changing the waterpump last year I drained the engine both sides using the plugs. However the coolant destroyed the heat shield that covers the cat convertor. So keep this in mind when you want to remove this plug to cover the shield with some plastic. Like others said before, if only changing coolant don't bother draining the engine.

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