So little fluid comes out of radiator drain!

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Jan 7, 2009
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Rochester, MI, US, World
On our 2016 Explorer 2.3 EB. Went to start doing drain/fills on the untouched factory Motorcraft orange coolant, only 45k miles but it’s been 6 years. I pulled the radiator drain plug and got out, at most, 3.0 quarts out of the 11.6 quarts the book lists. It seems like most vehicles will drain at least half of the total capacity through the radiator drain. Why did I get such a small amount out? The drain is at the lowest point in the system, and the radiator, reservoir, and all hoses surely have more than 3 quarts in them. Are there various check valves along the way or something? Just trying to understand it better. Anyway, from now on I’ll just suction out the reservoir and replace the fluid a couple times a year, as it’s much easier than pulling the plug and will get nearly the same amount of fluid out.
 
Just checking that you opened up the radiator cap on top? Let's say that that is all that does come out. You're still better to replace it the way that you're doing as draining it out will get any sediment that's hanging down in the lower cavity. Don't lose faith I just keep up doing what you're doing. Remember some people don't even change that fluid so you're already one up on them.
 
On our 2016 Explorer 2.3 EB. Went to start doing drain/fills on the untouched factory Motorcraft orange coolant, only 45k miles but it’s been 6 years. I pulled the radiator drain plug and got out, at most, 3.0 quarts out of the 11.6 quarts the book lists. It seems like most vehicles will drain at least half of the total capacity through the radiator drain. Why did I get such a small amount out? The drain is at the lowest point in the system, and the radiator, reservoir, and all hoses surely have more than 3 quarts in them. Are there various check valves along the way or something? Just trying to understand it better. Anyway, from now on I’ll just suction out the reservoir and replace the fluid a couple times a year, as it’s much easier than pulling the plug and will get nearly the same amount of fluid out.

Pull the lower Radiator Hose, you will get more out! You might get another quart or 2 out.

There is always more Coolant in the block versus the Radiator. JMO
 
You can get more out of if you disconnect both radiator hoses and use compressed air (wrap a rag around the air nozzle) to blow through the top hose.
 
You can get more out of if you disconnect both radiator hoses and use compressed air (wrap a rag around the air nozzle) to blow through the top hose.
That is a great point that I forgot to mention, but he might need to remove the thermostat to get more coolant out since the thermostat may be closed. You really do not want coolant blown back in your face.
 
Depending on the design, you might siphon antifreeze from "somewhere" if you leave the radiator cap on vs taking it off.

But your experience is not atypical.
 
You can get more out of if you disconnect both radiator hoses and use compressed air (wrap a rag around the air nozzle) to blow through the top hose.
How many people have a compressed air setup in their home garage? I'm sure some do, but my guess is most don't.
 
How many people have a compressed air setup in their home garage? I'm sure some do, but my guess is most don't.

I’m not looking to go to great lengths to remove as much coolant as possible. I was just curious as to why so little comes out. I’m leery of removing rad hoses from the plastic tank ends with how brittle plastic can get, especially with how hot the under hood temps get in this vehicle. I’m cool with just suctioning the reservoir every once in awhile.
 
How many people have a compressed air setup in their home garage? I'm sure some do, but my guess is most don't.
I have to believe most at home DIY’ers have at least a small compressor. I know I have in my 25+ years of working on cars and around the house.

Just my $0.02
 
On our 2016 Explorer 2.3 EB. Went to start doing drain/fills on the untouched factory Motorcraft orange coolant, only 45k miles but it’s been 6 years. I pulled the radiator drain plug and got out, at most, 3.0 quarts out of the 11.6 quarts the book lists. It seems like most vehicles will drain at least half of the total capacity through the radiator drain. Why did I get such a small amount out? The drain is at the lowest point in the system, and the radiator, reservoir, and all hoses surely have more than 3 quarts in them. Are there various check valves along the way or something? Just trying to understand it better. Anyway, from now on I’ll just suction out the reservoir and replace the fluid a couple times a year, as it’s much easier than pulling the plug and will get nearly the same amount of fluid out.

I’m guessing that the lower radiator hose has a curve in it creating a high spot that doesn’t allow fluid to drain easily. Couple that with not removing the radiator cap and thermostat and I think you found the problem.

Depends on what your comfortable with but you could just add distilled water to the radiator and cycle the coolant. Continue to drain and fill with distilled water until it’s mostly clear and then repeat this process with NON DILUTED antifreeze. Once you achieve the specified temp usually-35F you can stop. I have done several vehicles like this due to similar issues you have faced. I usually go through about 4 gallons of distilled water and 1-1/2 to 2 gallons of antifreeze.

Just my $0.02
 
You also may find that if you pull off a heater hose at the highest connection point, you'll get more coolant out of the engine. This is especially true if you don't pull the thermostat. Leave a heater hose disconnected when refilling until coolant starts to come out of it.
 
How many people have a compressed air setup in their home garage? I'm sure some do, but my guess is most don't.
Just use the exhaust port on your shop vac. Keeps the pressure low and pushes out the water. I've done that many times to get out the last bit.

Make sure the bag in the shop vac is clean and the hoses too so the exhaust air is clean.
 
Just use the exhaust port on your shop vac. Keeps the pressure low and pushes out the water. I've done that many times to get out the last bit.

Make sure the bag in the shop vac is clean and the hoses too so the exhaust air is clean.

Since my time was wasted, I'm open to sharing. Lots of modern forums lock threads to new comments except the OP after a few weeks. Time to get modern?
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