I have all my stuff and am planning on flushing my coolant and installing a new thermostat (Motorcraft).

I will drain the radiator, remove the bottom hose and remove the 2 block drain plugs. Just a couple of questions:

1. Should I flush the radiator (with a gardend hose) from bottom to top or top to bottom?

2. To flush the block should I just stick the hose in the thermostat opening and let it run?

3. I should fill the block prior to re-installing the thermostat, correct?

I am not having any overheating or leaking issues, just don't know the last time it was flushed. Replacing the thermostat so I figured it was a good time.

 

I did this recently, and here's how I did it. I already had one of those Prestone flush tees installed in one of my heater hoses.

- Disconnect your batteries.

- Drain all the coolant from the radiator into a five-gallon bucket (it will mostly fill it). Close the radiator drain.

- Drain both sides of the block into another bucket and leave the plugs out.

- Hook garden hose to the backflow tee and flush the block out for five minutes. Let drain. Replace the block plugs.

- Put the overflow nozzle in your radiator neck and turn the hose on again. Let the radiator flow for five minutes or so. Turn off the hose and remove the overflow neck.

- Drain some water from the radiator (enough to pour in flush chemicals, about 44 oz)

- Pour in two containers of the Prestone flush (sodium citrate) stuff.

- Reconnect batteries and drive the truck up to operating temperature.

The bottles say to drive it 3 - 6 hours over three days, and then drain. I didn't have time to do that, so I just did about an hour of driving and 24 hours of the flush being in the system. Then,

- Let truck cool off to ambient temperature (to avoid thermal shock)

- Disconnect batteries again

- Drain radiator and block

- Water flush block again, let drain, replace plugs

- Remove lower radiator hose and put the garden hose in the radiator neck and let it flush for five minutes

- Replace lower hose, fill radiator back up with coolant, reconnect batteries, and run it.

It'll probably have some air in the system. As long as your check ball in the thermostat housing isn't gummed up, it will bleed the air out by itself. Just check the coolant level after you've driven the truck and top off as necessary.

I am also replacing the thermostat, water pump, fan clutch, and some hoses, and installing a coolant filter at the same time. I really recommend you drop $40 or so on a coolant filter setup.

 

Specifically:

If you use my technique, you will actually do both. I figure that will get as much crud out as possible without more extreme measures.

That would work, but it'll make a mess. The easiest and neatest way is to spend $5 on one of those Prestone flush kits and splice it into one of your heater lines.

Doesn't really matter whether you do or not. I found that even after draining the block, the thermostat housing was still full of water, so unless you vacuum it out (or remove the water pump), it'll be a nonissue anyway.

 

Thanks for the info. I had briefly looked at the flushing kits but I think I remember it looked pretty difficult to get to the heater core hose in the van. I will have to check it out again.

 

Oh ... a van. Sorry, I should have paid closer attention to your signature line. I'm not sure how much of what I said applies to your setup (no experience with the IDI vans).

 

Same basic set up, just a little different packaging. I know in my other vehicle I used the Prestone Flush chemical stuff and it worked well. I think the instructions were to drain the radiator, fill with water and chemical, run vehicle at operating temp for 30 min. Then drain the radiator, fill with water and run at opperating temp for "X" amount of time.....repeat this step 3-4 times to get the chemical out. Then refill with coolant mix. I was thinking about doing this on my van, but I was a little worried about not getting all the chemical out.

 

Yeah, the bottle says you can do it either way -- a quick clean or up to a 3-day deep cleaning. I think as long as you do a water flush after using it and drain both your radiator and block, you'll dilute the chemical to the point where you don't need to worry about it. Besides, if you have any buildup, the sodium citrate will react with it and become inert anyway.