Location of the coolant drain hole in the engine block?

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.

 

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?)

 

Excellent! I have found it about 9 inches from the engine bottom, at cylinder #5 as you have said. Thanks!

 

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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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.

 

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.

 

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!