2010 5.4 coolant flush
 

I've got a stupid question concerning a coolant flush on my truck. Do I flush the system from the radiator, or the coolant reservoir?

I've been searching the net and can't find a definitive answer. This truck doesn't have a de-gas bottle, it's a regular reservoir.

Normally you wouldn't flush a radiator you would do a drain and fill method. You would take the cap off on your reservoir and undo the drain plug on the bottom of the radiator and capture the fluid in a drain pan.

Then your next oil change do the same thing again and you will have gotten most of the fluid changed.

Thanks for the reply. If I wanted to try and flush out the cooling system, how would I go about doing it? This truck has about 100k miles, and the fluid doesn't look like it's been changed. I bought it used. Would the water not circulate though the engine if I stuck a water hose in the radiator while it was running?

He's not flushing only a radiator. He wants to flush the cooling system, totally normal/common process.

I'd drain what you can, fill with water, drive a few min, drain fill with water. Do that until it drains clear. Then drain and fill with coolant. Might take some math to figure out how much water is left in the block, and pour in a heavier concentrate to get the 50/50 to come out.

Thanks for the advice. Ive got the Motorcraft VC-1 that I want to use as well. Since im flushing the system, im also going to replace the thermostat. I got a little confused on the youtube, as it seems everyone was flushing the system through their de-gas bottle, but since I don't have one, ill flush it through the radiator like I do on my '94.


The coolant capacity is just over 20 quarts on for the 2010 5.4. I figure ill fill it with 10-11 quarts of Motorcraft Gold concentrate, then top it off with distilled water. This after getting most of the hose water out of course. Its a new truck to me, I wanted to make sure my method was sound.

You're supposed to fill with a mix of 50/50 distilled water and coolant or use the pre-mixed kind. That's the reason for not flushing. It's a horrible idea to use regular tap water to flush. You have about 75% in your engine and head so you'd end up with 3/4 tap water and a small percentage of coolant. A big part of what coolant does is lubricate and inhibit rust and it depends on the a pure water and proper mix to do so.

When I used to work as an mechanic I lost count of the amount of head gaskets I changed because someone had a small leak and filled it with tap water. Eventually there was enough rust to act as an alkaline base and with the disimilar metals of the aluminum head and iron block it acted like a big battery and ate through the head gasket within a few months. Ever high school science class does the thing where they power a small light bulb by sticking in two rods of disimilar metals into a grapefruit. That's how batteries work.

There is no need for a flush if your system has had the proper coolant mix during those 100k miles. There shouldn't be anything in there to flush out. Only thing your doing is creating a problem for yourself down the road in a few years.

The thing is, I don't know how the previous owner maintained this truck. The fluid in the reservoir is dark brown. Hopefully he stuck with the factory coolant. If I decided to take a water hose to my radiator to try to flush the engine while its running, what would be the best way to remove the tap water? My plan is to keep refilling it with distilled water, revving the engine for a few minutes, drain water, repeat. This way there is mostly distilled water in the engine.


In your experience, only about 1/4 of water/coolant is actually removed after draining it? Are there better ways to remove more fluid from the system?


Thank you for your input, im trying to do this right the first time.

With the engine off I would take the top and bottom radiator hoses completely out. Take the thermostat out. Flush with a garden hose into the t-stat housing. If you get clean water coming out the bottom then your good.

Next buy some good 50/50 pre-mixed extended life coolant. Then pour that in to the housing until it comes out the bottom. Pour in an extra half gallon after that to be sure and get everything out.

Then do the same thing with your radiator. Check your hoses to see if you need new ones and put everything back with a new thermostat and gasket.

* If it's hard to get the hose into the t-stat housing you could put the housing(minus the t-stat) back in and re-attach the top hose.

* If you want to be sure and get it all you could lastly take both the heater hoses off where they attach to the intake manifold and flush them. When adding coolant you might have to use a separate tube with a funnel held up high to get enough gravitational pressure to get the coolant to go through it and the heater core. You'll be flushing in one of the hoses that go through the firewall. Not the intake.

Don't run your engine during any of the above. When you're done fill your reservoir a little extra (3/4 or so) full. Start it up and turn on your heater all the way. Let it get to normal operating temperature. Then when it sits overnight it might burp a little and suck down the extra fluid.

Then in a few months you can check the mixture with a tester if you want.

Flushed coolant last night, no rust found. May drain and fill the radiator again after driving for a few days. I didn't use a water hose after all. Ended up trying to flush it out with distilled water. Draining radiator again because I'm still not sure what kind of coolant was used prior. It looked kind of green.

Did you take the thermostat out and then re-attach the upper hose. I was thinking you might need to do that and then lift it up as you fill it in order to have gravity get you the pressure you needed.

Did it come out clear where the lower hose attaches?