Background: Over the last 11 years, I have read numerous postings and the inevitable debates on how to effectively flush the coolant system on the 6.0 engine. Lately, some folks have asked how to flush the 6.0. This is my approach on how to do a simple flush.

I am the original owner and although I normally do this kind of maintenance myself, the previous flushes seemed to come due in the middle of the winter so I splurged and paid the Ford house to do the work. It cost me about $80 to $100 labor for them to do it and I considered the money well spent and I stayed dry. I’m now at the 99K mark and the truck is due for a flush. After reading many posts and watching a few videos and also since the weather is nice, I decided to do it myself. As an aside, the truck is used about 50% of the time for towing my fifth wheel and I have towed through 46 of the lower 48 states and Alberta east including Newfoundland in Canada utilizing the Ford gold type antifreeze.

Current Situation: The truck is virtually stock-no tunes or other performance enhancements. There is no crud that is discernible in the degas container. I don’t seem to use or lose any appreciable amount of coolant. The last time I topped up to the “Min” line was 7K miles ago and it required a very small amount of distilled water. I added a Dieselsite coolant filter 35K miles ago and I have replaced the filter several times. Nothing of any consequence was in any of the filters.

The current batch of coolant in the engine looks a tad dirty but there are no floaters or other extraneous particles that can be seen by the naked eye. EOT/ECT delta at 65 MPH unladened on the flats runs between 10-12 degrees F and it has been consistent since I added a Scangauge II in December 2010. I replaced the thermostat that stuck closed and also the water pump in December 2013 when I was down at South Padre Island, Texas. ECT runs a consistent 190 degrees F unladened.

The Plan: I am replacing the existing Ford gold coolant. I have no need to change or upgrade to an ELC coolant. The first task is to remove all the existing coolant in the engine. The second task is to remove the tap water I am flushing with and eventually end up with the purest water reasonably possible in the engine. The third task is to add the antifreeze and bring the coolant up to spec for a 50-50 mix. The fourth task is to run the truck for a week and check for any problems.

Tools:

8 MM Hex socket (allen head type)for removing the driver’s side engine plug.
A Breaker Bar with a ½” to 3/8” drive reducer and a 3/8” drive ratchet to remove the engine drain plug.
Pliers to compress and remove the clamp on the heater hose.
Screwdriver to get the heater hose off of the engine nipple.
Deep socket for installing the Fumoto valve (can’t remember the size).
TDS tester that I use for testing the Reverse Osmosis (RO) water in the house (Amazon $10).
Blue water filter I use on the trailer when I am out.
Garden hose.
Hose adapter consisting of garden hose ¾” FHT x ½” FIP fitting, ½” threaded/slip coupling and a short piece of ½” PVC pipe. See Diesel Tech Ron’s video. Cost about $4.00 for parts at Lowes.
Ramps to elevate the truck on a slanted driveway so coolant comes out the driver’s side engine plug.
An extra “T’ shirt (More about that later).
A big pan to catch the old coolant.
A funnel for adding water and antifreeze.

Materials and Supplies:

4 Gallons of Zerex gold antifreeze.
Vaseline to lubricate heater hose back on to the engine nipple.
Vaseline for the gasket on the coolant filter.
F108-N Fumoto valve (reuse the “O” ring from the engine drain plug).
RTV sealant for the Fumoto valve threads (probably not necessary – I used a small amount).
A length of 3/8” hose to put on the Fumoto valve to direct the water away from you.
9 Gallons of RO water from the RO filter.
9 Gallons of Distilled water.
New Baldwin filter for the Dieselsite coolant filter setup.

Execution:

1. With a cold engine, drive the truck up on the ramps, put in Park and block the wheels. Place the pan under the radiator, remove the cap on the degas container, open the petcock and drain the radiator. While the radiator drains, test the water at the hose spigot. Mine was 638 PPM (parts per million). I added the inline RV blue filter and the reading went down to 499 PPM. I think the inline RV blue filter is really optional.

2. Now that the radiator is drained, remove the engine plug on the driver’s side. The coolant will come gushing out and therein lies the reason to have a spare “T” shirt. Let the engine drain. Clean up the hole. Remove the “O” ring from the plug, put it on the Fumoto valve with a small amount of RTV sealant on the threads and gently thread the Fumoto valve into the block. You may have to back it off a bit and try several times to get it threaded. Tighten it down snug. Ensure the valve is open. Attach the 3/8” hose to the Fumoto valve to direct the water away. The Fumoto valve will provide an easy solution to opening and closing the block drain for the next steps.

3. Assemble the hose adapter and attach it to the garden hose downstream from the blue filter. Find the heater hose which is next to the alternator, remove it from the engine nipple and insert the hose adapter into the hose. You are now ready to do a reverse flush through the heater core. Turn the heater **** all the way up to its highest point and leave it on during the rest of the procedures.

4. Turn on the spigot and flush away. When everything seems clear, start the engine for a moment or two and let the engine circulate the water. Make sure that you have enough water in the engine as you now have two exits for the water – the block valve and the radiator petcock. Start the engine again for a moment or two and continue to flush. Shut the engine off and continue to flush until you believe the water is clear. Flush out the degas container and check for crud. If necessary, remove the degas bottle and clean.

5. Shut the petcock and the Fumoto valve. Reconnect the heater hose to the engine nipple using a little Vaseline to lubricate the hose. You may want to use a little emery paper on the nipple to clean it up. Put the clamp on the hose in the same spot it came off.

6. Slowly fill the engine with the garden hose through the degas container and start the engine. You’ll probably have some air in the system so take your time. Put on the cap.Take the truck out for a short ride until the ECT comes up to 190 degrees F. Put the truck back on the ramps and let it cool down. It won’t take that long. Drain the block and the radiator and then close the block drain and the radiator petcock.

7. Slowly fill the engine with RO water through the degas container. My RO water tested 55 PPM ( I just ordered a new RO filter as mine is at the end of its life).Drain some of the water since you will only be able to get about 20 quarts into an otherwise 27 quart engine. Making sure the petcock and Fumoto valve are closed, fill the engine through the degas bottle.Put the cap on. Take it out for another short ride getting the ECT up to 190 degrees F. Put the truck back on the ramps and let it cool down. Drain the block and the radiator and then close the block drain and the radiator petcock. Sample the engine water from the engine. My engine water tested at 149 PPM.

8. Refill with distilled water. Put the cap on.Take it out for another short ride, let the truck cool down and drain the engine and radiator. Close the petcock and the Fumoto valve. Remove the Baldwin coolant filter and replace. Put a little Vaseline on the rubber gasket. I did not retest the engine water. I would estimate it would be at 75 PPM.

9. Now is the time to add the antifreeze. You should have a capacity for additional antifreeze/water of 18-20 quarts. Put 14 quarts of antifreeze in the engine through the degas container and fill up the rest with distilled water.

10. Start it up, cap it, check for leaks and take a short ride. Refill degas container to the "Min" mark if necessary. After a week, still no leaks and I tested the coolant. It registered as -45 degrees F. Coolant looks clean in the degas container, both radiator hoses are hot and the heater works fine. No strange noises and the truck runs well.

Conclusion: I watched the Diesel Tech Ron Video and he recommended in the video that it was not necessary to remove the engine plug on the passenger side for a simple flush. I used a TDS tester and some may take issue with the applicability of this tester for this application. However, it did give me reference points during the procedure. I used RO water which was free instead of buying more distilled water. Either one will do for the second flush.
All in all, it was a pretty simple process and since I mowed the grass during the periods the engine was cooling down, there was very little idle time. I hope this helps anyone who wants to do this simple flush.

 

Nice write-up, Bob.

 

That was a very clean report sir, thank you… it helped me incredibly.

 

Have an extra radiator drain plug handy. They get old and brittle.

 

Guys, I know this is an old post, but could someone help me out on one detail? I looked at the coolant system layout and cannot decide which is best.

@Texas Bob says he runs the truck up on ramps so he does not have to open the Passenger side block drain. Are you ramping to lift the front end? Or, to lift the passenger side (so the fluid all drains on the drivers side)?

All things being equal, in this case symmetrical, it would make sense potentially to cant the truck towards the drivers side so the Drivers side drain is the lowest point.

Thoughts?

 

The only way to get all the liquid and debris out of the separate water jackets in the block is remove both block plugs.

 

Thanks for the verification on that @TooManyToys.

 

Thank you very much!

 

I didn't have time earlier to make this. Coolant/water would be left in the block. It's actually worse as the engine tilts low to the back.

 

@TooManyToys. Thanks for that info as well. I appreciate the time you took to get the pictures. Breaking out the crayons for people like me most effective. So, what I gather is the following.

1. Just have the truck level. Tilting will not alter the result in any significant way.
   1. Inside the block the water reservoir is like a P-trap based on the drain plug location versus the inlet and outlet on both sides.
2. To do it right, pull the starter and add the valves so you do not have to mess with it more than once
   1. Doing multiple fill and drain cycles using distilled water is the only other way to get most everything out, but not ideal

Apologies, I over-think and need to understand why things work or do not work.

 

The real P-Trap is at the oil cooler. The only true way to get the debris out of the oil cooler intake is to back-flush with air and water from the oil cooler output, and take the water pump off so the debris to not go into the block. Trying to just use the lower radiator hose as the exit port, the debris has a better change not following the flow, and go right into the drivers side jacket.

I'm also not a fan of using valves at the block drain ports. You want as much flow out of them as possible. SRMastertech had a good video of goosing the throttle and getting everything out of the block forcefully.

 

Glad you mentioned the back flush of oil cooler pushing crap into the block. I was going to do that. I think I'll be removing the oil cooler to clean it out now. I was skeptical of valves so glad you said something.

Already pulled the Degas and cleaned it. Drained and flushed the radiator manually. Back flushed the Heater core. Block and Oil cooler are all that are left. Then I'll reinstall everything and do a full system flush to make sure it is clean and switch to EC-1 coolant Oh, and add a coolant by-pass filter when I'm done. Not using the acidic chemicals just to be paranoid about doing damage. That is the reason for doing the components individually. Was just really hoping to not have to remove the starter. LOL Just one more thing. Always just one more thing.

Doing a semi-complete overhaul of the truck. New Filters, fluids, etc. Cleaned the EGR Valve and EGR. Cleaned the HFCM, Front suspension grease, and investigating differentials for possible leaks (front maybe), Blue Spring Kit, High Idle Mod, ZooDad Mod, Added old small tablet for Torque Pro. Turbo Drain Line, Upgraded intercooler pipe, Adding the F650 lower center dash for up fitter switches (for lights, etc. later). replaced most Brake and Power Steering fluid through displacement since I am not sure how to completely flush and not sure I'm comfortable doing that. Converting all Cig Lighters to USB ports. Now flushing coolant system, changing Thermostat, and adding coolant filter. After that a Wheel lug that is broke, the horn shorts out the steering wheel circuit fuse, Sun roof broke but I do not care since it is closed, and replace the old rear air bag suspension (that is going to the shop though). Still debating and researching Crankcase ventilation and the Blue Wire mod for the cooling fan. All in the last 3 weeks and have never really worked on vehicles before. Heads, FICM, Water Pump, Injectors, Turbo, etc... I'm only going to do if they break at this point. Any suggestions are welcome.

Long way of saying I'm clueless and trying to figure out every step I can skip or do an easier way since it was running well before I started. I just started one day and figured I'd do every reasonable preventative thing I realistically could myself. While I have it opened, do a couple of foundational cosmetic things like the dash replacement. Kind of wishing I paid someone else to do it at this point since I do not have the time. LOL. But it is only at ~130K miles and want to see it hit over 400K if I can. Get it mechanically good to go then clean up and fix up the cosmetic after. I love the old truck and do not want a new one even if I could afford it. It gets the job done.

 

Agreed the valves are not great for the initial flush with hose water because of the flow reduction. Where they really shine, however, is the draining/refilling cycles that are required to get the tap water out of the block, or at least dilute it as much as possible. After the initial flush, which includes removing the thermostat and doing the SR MasterTech routine, the valves go back in so I don't have to keep crawling back under there to remove/reinstall the plugs. That gets REALLY old after half a dozen cycles, and the passenger's side is nearly impossible with the starter in place. I would end up blowing my brains out if I had to remove and reinstall the starter that many times in one day.

 

I haven't been on the site in a couple of weeks and I noticed that Lazarus had restored a post I made back in 2016 about how to do a coolant flush and I believe he had a couple of questions about my writeup. There were also some critiques and additional suggestions which I think are worthy of discussiion. I have always done the coolant flushes around the 3 year Ford suggested mark so I may have been lucky that there were no significant particulants in the coolant I could see. Early on, I had installed a Diesel Site coolant filter and I would change that as well. The filter always looked good.

Now to clarify my reference to having the truck on a tilt. My driveway in front of the garage is on a tilt so I just raised both sides of the truck with ramps. I don't know if this helped in the cleaning process. If my driveway did not have a tilt to it, I would have put a board under the passenger side ramp. Did it do any good? I don't know but it seemed like a good idea at the time. With reference when to put the Fomoto valve in the passenger block drain, I flushed quite a long time with the garden hose setup until everything ran clear. I think it might be well to drain it a second time without the valve - surely it couldn't hurt.

I changed the coolant a while back after doing the flush again and replaced the coolant with ELC. Details can be found under my sig. Short conclusion, just do it!

I also have a tag in my account. Not sure what it is. Try to stay cool. I'm reminded of the quote from General Sheridan when he posted to Texas in the late 1800's. "If I owned Texas and I owned Hell, I'd rent out Texas and live in Hell."

 

I haven't been on the site in a couple of weeks and I noticed that Lazarus had restored a post I made back in 2016 about how to do a coolant flush and I believe he had a couple of questions about my writeup. There were also some critiques and additional suggestions which I think are worthy of discussiion. I have always done the coolant flushes around the 3 year Ford suggested mark so I may have been lucky that there were no significant particulants in the coolant I could see. Early on, I had installed a Diesel Site coolant filter and I would change that as well. The filter always looked good.

Now to clarify my reference to having the truck on a tilt. My driveway in front of the garage is on a tilt so I just raised both sides of the truck with ramps. I don't know if this helped in the cleaning process. If my driveway did not have a tilt to it, I would have put a board under the passenger side ramp. Did it do any good? I don't know but it seemed like a good idea at the time. With reference when to put the Fomoto valve in the passenger block drain, I flushed quite a long time with the garden hose setup until everything ran clear. I think it might be well to drain it a second time without the valve - surely it couldn't hurt.

I changed the coolant a while back after doing the flush again and replaced the coolant with ELC. Details can be found under my sig. Short conclusion, just do it!

I also have a tag in my account. Not sure what it is. Try to stay cool. I'm reminded of the quote from General Sheridan when he posted to Texas in the late 1800's. "If I owned Texas and I owned Hell, I'd rent out Texas and live in Hell."