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Location of the coolant drain hole in the engine block?

Discussion in '360/430' started by modificator, Jan 3, 2021.

  1. modificator

    modificator Karting

    Apr 12, 2020
    92
    Florida
    Full Name:
    George
    Hello
    After spending a long time reading the coolant change threads I'm concerned that the generally recommended draining of half (or less) of coolant from radiators (followed by vacuum re-fill) may not be a best solution due to potential incompatibility of fluids (OAT/HOAT/IAT etc) - it's difficult to be sure about the type of fluid put in under the previous ownership.

    Even with multiple distilled water flushes, it would still be better to drain the block as well (I think). So where are the 2 drain holes in the engine block? One post says that the left side is easier to access and removes most of the fluid, so that would be a good place to start.

    Also is there a way to push-out the old fluid by pushing in the fresh one, similarly to pressure changing brake fluid? I can't think of any without thermostat removal, and removing the thermostat would probably be too much work comparing to just draining.
     
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  3. tazandjan

    tazandjan Three Time F1 World Champ
    Lifetime Rossa Owner

    Jul 19, 2008
    35,290
    Clarksville, Tennessee
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    Terry H Phillips
    Affirmative, you can vacuum fill the cooling system, eliminating the need to bleed the system. Your tech should be able to show you his system for doing that or just look it it up on the internet.
     
  4. modificator

    modificator Karting

    Apr 12, 2020
    92
    Florida
    Full Name:
    George
    Thanks, but all I have read so far (including Aldous Voice website, AirLift use etc) uses vacuum to add coolant after first draining half of it. Can vacuum be used to actually remove the coolant?

    If not, the original question still holds - how to drain the engine block? (or how to remove more than half of the coolant in any other way?)
     
  5. BrettC

    BrettC Formula 3

    Aug 13, 2012
    1,574
    Calif
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    Brett
    I use my air compressor to fill the expansion tank, air blocked with a rag, and it pushes out probably another 1/2 gallon or so. I think I am getting maybe 2.75-3+ gallons out. Then I use an airlift tool to refill. First time full purge is a pain, I just kept flushing it with water as I haven't wanted to crack open the block seals. Sorry, can't help with those locations. HTH
     
  6. yelcab

    yelcab F1 World Champ
    Consultant

    Nov 29, 2001
    11,487
    San Carlos, CA
    Full Name:
    Mitchell Le
    Remove the under panel
    Jack the car up (best with a lift)
    stand under the engine, look up at the SIDE of the block where Cyl 5 is, you will find a brass plug. It should fit an Allen socket, 5 or 6mm. Use a socket, not an Allen key and be careful not to strip the hole.

    There is a similar drain under Cylinder 1 position but you only need to drain just one. Get ready for a face full of coolant as more than 1 gallon will come out.
     
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  8. modificator

    modificator Karting

    Apr 12, 2020
    92
    Florida
    Full Name:
    George
    Excellent! I have found it about 9 inches from the engine bottom, at cylinder #5 as you have said. Thanks!
     
  9. modificator

    modificator Karting

    Apr 12, 2020
    92
    Florida
    Full Name:
    George
    #7 modificator, Jan 6, 2021
    Last edited: Jan 6, 2021
    A hose at radiator (#2) is still full of coolant after radiator draining, so draining radiator with the hoses at the water pump disconnected will drain more fluid. It seems hose #1 delivers coolant to the radiators (thermostat housing and the bleeding screw), hose #2 is the return from the radiators. Is it correct? What is the hose #3 and which way it flows? Is it to the cabin heater?

    I'm still looking for a way to power bleed close to 100% of the coolant in one step and need to understand all the hoses first.


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  10. AandSC

    AandSC Formula Junior
    Silver Subscribed

    Dec 12, 2016
    423
    Jax, FL
    Full Name:
    Allen
    Did you try blowing fluid out using compressed air like BrettC recommended? I did that recently on my Mini and was surprised how much fluid came out using that method. Curious as I’ll be changing my 430’s coolant for the first time in April/May.
     
  11. modificator

    modificator Karting

    Apr 12, 2020
    92
    Florida
    Full Name:
    George
    Not yet, Brett said it gives about 1/2 gallon, and there is still about 2.5 gallons left in the system after draining the radiators. So my thinking is that if I understand all the cooling hoses and which way they flow and which are restricted by thermostat, water pump, heater valve etc I can find a path (or paths) on the cold engine which would allow to push ALL the old coolant out by pushing distilled water in.

    And after only the distilled water comes out (all old coolant is out), we can drain the radiators again (half the water out) and vacuum feed a couple of gallons of new concentrated coolant in, and we are done.
     
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  13. modificator

    modificator Karting

    Apr 12, 2020
    92
    Florida
    Full Name:
    George
    Alternatively to pushing water in, perhaps cranking the engine (water pump) with disabled ignition for a minute or so or putting an electric power drill on the water pump to rotate it, would allow the water pump to push the old fluid out.
     
  14. AandSC

    AandSC Formula Junior
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    Dec 12, 2016
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    Jax, FL
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    Allen
    Thanks for the response! Look forward to hearing your results and what works best.
     
  15. modificator

    modificator Karting

    Apr 12, 2020
    92
    Florida
    Full Name:
    George
    BTW, hose #3 sends coolant to the front, where it goes through a small electric pump, cabin heater, heater valve and back to the engine through a T in hose #2.

    So there are 2 hoses going to the radiators, #1 blocked by thermostat, #3 blocked by the small electric pump in front. Return is by #2 and a bleeder hose going to the tank/nourice.

    Disconnecting #3 at the electric pump in front would be quick and easy. Pumping water into the tank (and potentially with 2 bleeder hoses disconnected at the tank) would flush the engine with the water coming out at #3 disconnection. 2 problems:

    1) Hose from the tank enters the engine near the water pump, close to the #3. Would the coolant from the tank actually go through the engine on the way to #3 or totally bypass the engine? (could it be fixed with the water pump running - cranking the engine and rotating coolant inside?)

    2) Relatively small diameter of #3 would make the process slow

    Does it make any sense?

    Or should we disconnect the #2 at the front of the car and let the water flow backwards out of it without using the water pump? After understanding all the external hoses now the question is how the coolant flows inside the engine.

    Thanks to @flash32 for a background support!
     

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