I’ve been doing these like this for a long time and I have great confidence this is ‘the best way’. I respect gooch’s knowledge about coolant types, etc - but feel this is a more practical and highly effective alternative to his flush procedure.

Start by opening the radiator drain and block drains and collecting the old coolant. Also remove the heater core return hose from the top of the water pump. Use the garden hose to back flush the heater core and also flush down into the water pump. Then replace heater hose.

Remove t-stat and put housing back on without it. I use a ‘modified’ t-stat for this. This allows full flow from radiator to block and greatly enhances flush efficiency.




Use this trick to mitigate dropping the rear bolt on t-stat housing. (Piece of shop towel holds the bolt on the socket)





Stick the hose into the degas bottle and let it run until degas bottle is full/overflowing and then crank engine. Let the hose run until the water runs out of all drains clear.





Then, replace drain plugs and fill system with tap water. Drive around the block and repeat. I don’t use thread sealant on plugs for this part of the process. It’s not going to leak enough around the block to hurt anything. Do this until drains stay clear.

Before installing the block drains, remove heater core hose again and blow the heater core out. I use the Big Bad Wolf method. If you want to use compressed air, just be aware this system is designed to handle 16psi - don’t break anything!

Replace the t-stat and pour some distilled water down into the water pump, heater hose and degas bottle to ‘rinse’ tap water from engine for good measure. The amount of water with minerals that remains in the system is insignificant and won’t cause any problems, but a little rinse won’t hurt either.

Replace drain plugs - using Teflon tape (carefully) or thread sealant.

Dont re-install heater hose just yet!!!

This is the perfect time to install a positive coolant shut off on the heater core SUPPLY. Yes, even if you have a ‘factory shut off valve’. The factory version is on the return hose and has s hole in it - it still allows heater core to get HOT. I close this valve all summer and crack it open in the fall when using heat in the AM and AC in the afternoon.

A 3/4” PEX barbed valve works PERFECT for this. Be sure to locate clamps in such a way that they don’t rub the other hose. SSJ specifications require less than 5* rotational variation of finished clamp location. If you don’t have the OCD, just go all ***** nilly if you want!!






Now you can start filling the system with coolant. L99+ will get ELC. I use Peak Final Charge because it’s available locally, but all OAT coolants are compatible and can be mixed if you needed to top off later. For E99 and older trucks, I use Fleet SCA Pre-charged concentrate. I prefer concentrate and distilled water - adding the concentrate first.

Ill add pics of these coolants later...




The system holds about 7.5 gallons.

Fill the system until coolant comes out of the heater core return on top of water pump. This will help with burping air later. Replace heater core hose and continue filling - but don’t fill the degas bottle more than 1/2 way!! Less is better.

Youll want to start the engine and let it run in high idle if you have the option - with heater core shutoff OPEN and AC on high. It takes a long time idling for the t-stat to stay open long enough to burp air from the block. Don’t fill the degas bottle so when it burps you don’t get a volcano and spill your fresh, expensive coolant on the ground!! Leave radiator cap off while idling. Once you’ve got 6gals or so in the system, you can install radiator cap loosely and drive the truck. Stopping frequently to see if it burped and bringing level back to 1/2 the degas bottle. Generally, after the engine fully cools down, the air will be displaced and it’s ‘safe’ to top off the degas bottle.

ELC is basically a permanent coolant for our trucks. No SCA monitoring and no flushing required.

If you use conventional or pre-charged coolant, you’ll need to monitor and add SCA and perform 100k mile cooling system flushes.

 

great write up, thank you

you right on the degas bottle fill level!

What oring do you use for thermostat, the split motorcraft one?

 

Maybe I shouldn’t admit this but I believe my coolant is what was installed by the factory. It checks good with the strip test and looks ok. We’re sitting at 100k miles on this 20 year old truck. I have no signs of any issues at this time.

Am I really a super bad boy here with the no service yet? I’ll admit I don’t do any regular service on coolant in any of my vehicles beyond strip testing.
— On a side note I also recently checked brake fluid with strips and was surprised to find my truck was in desperate need of a flush. One giant bottle of fluid later and all is well.

Is the 2001 filled with ELC from the factory or is this what is recommended to change to when flushing?

I see you recommended 100k for subsequent treatments. What is your recommended change interval when it comes to flushing and replacing the factory fill?

I figure I’ll throw my stupidity out here and pose the questions maybe others are too embarrassed to ask.

FYI anytime I ask the parts store (my good one) what coolant to run they ALWAYS recommend the “mixes with anything” type. I know that’s not the correct answer and it drives me crazy.

 

Jason I have the OEM valve and the Dieselsite Cold Rush upgrade as well.

Diesel SIte Cold Rush

We see some 90-100 days out here in Denver but with crazy low humidity 9-13% just moving air seems fine. Would you recommend adding the Pex valve to the other hose under the hood and leave it closed in the summer or just running with what I have? Then when summer passes I can just open the PEX valve use the the other valve combination for the shoulder seasons.

 

Whatever comes with t-stat. This one used the square edged o-ring on top of t-stat.

 

100k Miles is the recommended flush interval with conventional coolant (‘green’). It’s *time* for service.

You need to have been testing coolant for SCA and adding as needed.

Test strips:

SCA:

None of these trucks came with OAT ELC like I’m using here. (The kind we need to get out of SCA’s and coolant flushes).

 

It would not hurt anything to add the valve. I think it helps.

 

Well done Jason!

I have added this thread to the 7.3L PSD Tech Folder for future reference and easy access.

 

Thank you sir. I’m pretty sure I’ve used those in the past with good results when my uncle got a pack (we share).
More recently I’ve used this
It looks like I should have been checkin g for Molybdate and Nitrite levels instead. Oops. That’s why you’re the expert an I’m the pupil.

 

This (coolant) is the most often neglected thing I find on these trucks. Many people who are really good at PM miss proper cooling system maintenance because this detail is unique to our trucks.

 

Spray those block plugs with PB Blaster for 4 of 5 days ahead of time. Make for easy no issue removal.

 

Good call!

Also, these don’t need a ton of torque to stay in and not leak. Gudensnug is adequate when putting them back in. If yours are rusty, consider replacing them with brass plugs.

My biggest pet peeve when wrenching is working behind some ****** that overtightens EVERYTHING. For example, I had to use a cheater pipe to bust the turbo and pedestal bolts loose on this job. Literally afraid the bolts would break. Don’t be ‘that guy’, mmmmkay???

 

that is extremely more common in the 6.0‘s. The 7.3s rarely have that fail unless very souped-up. My understanding is usually it’s a failed oil cooler Or injector O-rings.

 

subscribing.....

 

Super awesome! Thanks Jason
lots of good info. Thanks! This has been on my to do list for awhile. I need to do this and oil cooler orings before it gets cold out.
For a new to me truck. How do I know what coolant is in the resivoir? I know the color really isn't an indication.