7.3 Ford coolant additive

Don't forget to change the recovery bottle pressure cap. I cannot emphasize that enough. The caps lose their ability to hold system pressure and bad things happen inside the block (hot spots) without the system pressurized. You need that pressure to raise the boiling point of the coolant to mitigate any hot spots.

7.3 are basically bullet proof except for the powdered metal rod engines but even those will run almost forever so long as you don't over fuel them. My 97 has forged rods. I could crank it up to 500 horse if I wanted to but I see no need. Fine where it is. Always has been.

Good engines. Much more reliable than the new Tier 4 DEF/DPF/ICM controlled messes. Nothing much to fail and parts are inexpensive.

I'd suggest doing a turbo pedestal delete but that is for another time.

I want to thank everyone for the information, I now have a better understanding.

As I said previously, the additive, whether it's the Ford Approved VC8 or DCA4 (which is the Cummins flavor, both degrade with heat and cool cycles in the engine so interval testing with a Ph strip is a necessity and like I also said, Fleetguard makes a nice test kit (what I use) as well as Ford. The Fleetguard kit is expensive but cheaper overall because it has many many test strips in it. I'm using the same kit I bought back in 1998 and I still have plenty of strips left. So long as you keep the bottle sealed and the dessicant pack in it, it will last forever.

Big Toe is correct, the coolant plug above the starter is a pizzer to remove, Just as easy to pull the starter out to access it.

I did my oil cooler last summer (replace the 'O' rings). Not too bad, just messy. If you don't use the additive, eventually your oil cooler will fail.

My 350 is easy to work on. It's 6 over stock with a front axle flip so accessing stuff is pretty easy, lots of room under there. In fact I can sit under the side of the engine on the ground. Did all that way back when in 98 and now that I'm almost 70, I kick myself for lifting the truck. Hard to get in and out and my wife hates it but the view is nice once you get up there.

I'm the old fart tooling around in a jacked up 350 4x4 with a full banks kit and straight exhaust on 33 x 12.5's. I to drive it, makes me feel like a kid again and with an ARB air locker in the front and a Detroit Tru-Track in the back, it will go about anywhere I want to go with my truck camper in the bed.

The principal concern with using a different coolant chemistry other than the coolant that the truck was originally filled with is the sealant used to retain the injector seat cups. The sealant that International used in 99 and earlier 7.3L engines was known to be incompatible with the chemistry used in Gold coolant. For the 99.5 update (or thereabouts), International changed the injector cup sealnt to one that would be compatible with future coolant chemistries, but this took a few years for Ford to verify before approval.

What is interesting to me is why Ford withdrew the approval, and returned to recommending Green conventional coolant (with the appropriate proportion of VC-8 SCA), rather than the either Green or Gold allowance that previously approved for 99.5 through 2001 7.3L engines (2002 and 2003 came with Gold factory fill). Maybe Ford learned something through dealer service feedback over that 10 year period of time that caused Ford to alter their position again.

Since I'm not privy to that collection of data, it's just easier to stick with what Ford recommends, which ironically, is the conventional green coolant that is both the cheapest and the easiest to find any time, any place, any hour, any store, any town USA. Some folks go all out and replace their coolant with super expensive 200,000 mile rated coolants. That's all fine and dandy, until the oil cooler O rings fail, the water pump seal fails, the radiator plastic tank to core crimp bites the dust, the heater core needs repair... any number of things that require some or all of the coolant to get dropped.

Having the facility and tools and buckets and filters to recover and reuse the coolant is a lot to expect from the stranger who helps on the side of the road... so it is nice to be able to simply remove any doubt of contamination by going with clean bottles of coolant and distilled water. Having it available at a grocery/convenience store that is open 24/7 is an added plus. Sure, there are truck stops on the highways, but not everyone camps solely on the interstates.

The VC8 (or Fleetguard DCA4) is a little harder to find, and getting harder and harder as the years go by, given that SCA's have been phased out of necessity in modern engine coolant chemistries. However, the small pint bottles of VC8 are a heck of a lot easier to carry around than gallon sized jugs of coolant.

Anyway, a conventional green coolant will need the SCA added at initial fill, and then tested thereafter to see whether the initial dosage of additive has depleted over time, and perhaps needs to be supplemented a little bit later on. The exception to the addition of VC8 at initial fill would be if the conventional green coolant selected is labeled as "Pre Charged". In that instance, adding VC8 would be redundant, and could be harmful to the water pump seal.

Ford did a double reversal on approving coolant chemistry change in the 2000-2001 years of the 7.3L. First Ford said no, treating the 2000 and 2001 model years just like the early 99's, which Ford has always said no about. Then, around 2004, Ford said YES, it was OK to change the Green coolant in the 2000 and 2001 model years to the Gold coolant Ford used in the 2002-2003 model years.

(To be more correct, I should say "late 99", which is also called "99.5", instead of just saying 2000. Also it is possible that some 2001s were factory filled with Gold... but I'm just roughly speaking from memory here, not attempting to be exact.)

Anyway, for about 10 years Ford approved Green and Gold coolant in 99.5 through 2003 trucks, but then Ford changed again, withdrawing their former approval of using Gold coolant in trucks that were originally filled with Green. The current Motorcraft coolant charts reflect Ford's second reversal in position, when compared to equivalent Motorcraft coolant charts from five years ago, and compared again to coolant charts from fifteen years ago.

Another situation where it may not be a good idea to add VC8 is if you use a coolant filter that has SCA cubes inside that dissolve over time.

Most 99-01 7.3L engines are better off without the precharged time release coolant filter, because those filters can introduce too much SCA to the coolant, and the granularity of the precipitant drop out is what destroys the water pump seal, which is the leading cause of water pump leakage failure in the 7.3L.

Some people change coolant chemistries to get away from having to deal with adding VC8 initially, then monitoring periodically with test strips, then adding maintenance amounts of VC8 per the results of the test strips. However, to change coolant chemistries requires completely draining and flushing the entire coolant system, which isn't easy.

Even after pulling the plugs on both sides of the engine block, including the difficult to access plug above the starter, there can still be almost a gallon of coolant (or diluted flush water) remaining in the system. How much of that gallon is in the water jacket below the plugs, in the oil cooler, in the inherent p trap passages of the heater core, or combination thereof, is anyone's guess.

colliehauler wrote:


One other question should you use the VC-8 from the start on a fresh fill of coolant, or later to control the ph?

Yes... add the appropriate ratio of VC8 to the fresh fill of green conventional coolant... UNLESS the coolant you purchased is already "pre charged"... then in that case obviously there is no need to add VC8.

BigToe wrote:

colliehauler wrote:
In a prior thread the number for the coolant additive was pf-22 from ford I found VC8 is this the same?

PF-22 never existed.

PM-22 was a fuel additive, not a supplemental coolant additive.

FW-16 was the coolant additive for the 7.3L.

VC-8 is the replacement for FW-16.

Thanks for the clarification, I was going by info on the thread.

One other question should you use the VC-8 from the start on a fresh fill of coolant, or later to control the ph?

Myself, I'm an Archoil fan and have been for years. I use their fuel additive in my truck and in my farm tractors too and I use their oil additive in the 7.3. Made a huge difference in starting the engine and I picked up some fuel mileage as well. Not enough to offset the additive cost but a bit.

This last summer I had to replace the right side injector harness (the one that routes through the valve cover and fires the injectors and energizes the glo plugs) and did the left one as well. I was amazed how clean and free of any varnish or sludge the overhead was. Just as clean as when it came from the factory I suspect. I could see all the paint marks on the overhead and read with no issues the labels on the injectors.

Was glad I have an OBS truck. A new body style truck would have entailed pulling the cab off the access the right valve cover. It was tight, but doable with some cussing on my part.

colliehauler wrote:
In a prior thread the number for the coolant additive was pf-22 from ford I found VC8 is this the same?

PF-22 never existed.

PM-22 was a fuel additive, not a supplemental coolant additive.

FW-16 was the coolant additive for the 7.3L.

VC-8 is the replacement for FW-16.