Coolant Replacement and Frozen Block Drains
 

The drain plugs for the coolant on my engine block are frozen and I am unable to completely drain the antifreeze out of the motor. I can get the coolant out of my radiator of course by pulling a hose or using the blue drain screw.

I sourced some Zerex G05 finally after sometime to replace the Prestone "All Makes and Models" 50/50 antifreeze that is in the car already.

The only option I can think of flushing the two year old coolant out is:

1) Drain the 2 gallons held in the radiator

2) Refill with distilled water

3) Run the car with the heater switched on until the thermostat opens

4) Drain the radiator again after it cools off

5) Repeat same process two more times for a total of three flushes.

Is this a feasible way of flushing without trying to break my block plugs clean off?

I take stuck fasteners as a personal challenge, try some rostoff or CRC freezeoff, or maybe some heat, and/or impact driver.

Yep. Me too. I use PB Blaster to soak. Use anti-seize when re-installing and DO NOT OVERTORQUE.

Not possible. The driver side is rounded and the passenger already does not budge. I have seen one block that had a piece chipped off of it when someone attempted to break it loose.

With regard to my flushing question, this is the only method I can think of using distilled water to lower the concentration of the current antifreeze type in there now. The issue with the drains was discovered during my TB/WP DIY in 2013.

Drill it out and retap?

Is it possible to run a flush kit?? I know they use to have them where you could hook up a hose and run water while the motor runs. A friend use to do it years ago. No need to drain the block.

Umm well ............if you remove the water pump,
you will drain the block...........
try that

^^ that's a lot of work...

2 year old coolant? Get a cheap tester, bet it's still good.

I remember there was a flush kit. It was inserted in one of the heater hoses. You would open up the radiator, hook a hose up to the heater hose, run the motor until clean water came out. Not sure they even sell them any more.

Yes, indeed; I had one i installed in a BMW 2002 I imported years ago.

If you have room to maneuver just loosen the heater hose (maybe the return hose) and let it rain with hose in filler; though, I would do that after flushing engine intact to displace as much coolant as possible.

Andy, pull the two hoses. Top hose at the radiator, and rotate it up on the engine nozzle. Lower hose from the thermostat housing. Best to pull the whole thermostat housing really, so the water will come out of the block while cold. Put the end of the garden hose in the end of the top hose and run the hose for a while. That will get the remaining Prestone out of the block. Then pour a few (half a dozen?) gallons of distilled water through the same way to get the bulk of the minerals load out too. Put it all back together, and add your coolant first. Gallon to gallon and a half, since it doesn't really freeze hard where you are. Add a bottle of Water Wetter first. Than add diistiled water to finish, if it will take it. A little more than half of the coolant remains in the block, so you have a little less tan 2 gals total you can put back in.

The block plugs:

I use a 6-pt socket 1/2" drive, and a long handle to get a hard initial snap of torque to get the plugs loose. Best if the block is hot for this if they are stubborn, but that means you get to wrestle around under the hot exhaust headers too.

The factory torque spec is at least 2x what it should be for those bolts. Put teflon thread sealing paste on the threads and the sealing face of the block, the drain plug, and the aluminum washer. Tighten to 12-16 lbs/ft only, and you be golden. You'll also be able to get the plugs out easily in a year or maybe two when you go through this exercise again.