I recently changed my antifreeze in my 93 7.3 IDI. I thought it would be a simple thing (been doing it for about 45 years to gassers) I put NAPA KOOL in with the new mix (Prestone)and it was suggested I check periodically with test strips. WELL, you would think I was checking to insure that I had the proper propellant mixture to send the Shuttle to the moon. Why does everything have to be so damn technical? I Googled Fleetguard test strips and ended up where there was extensive discussion about DCA-4, DCA-2, NAPAKOOL, etc. It seems like everyone has his opinion. I'm not looking for rocket science. I just want a SIMPLE STRAIGHT answer. Am I alright using Prestone antifreeze, adding the recommended dose of NapaKool and using a test strip occasionally to see how things are? If so, WHAT KIND OF TEST STRIP SHALL I GET????? Thanks for your time.... Tom

 

All I use is a simple hydrometer to measure coolant strength. Is that what you're wanting to do?
Bob

 

Use the same make of test strips as the additive you are using. Checking at oil change time and adding as required is all you should need to do. You are checking for SCA's, not only coolant strength. I would use a convential coolant, rather than long life. I have had issues with older engines as far as gaskets and seals are concerned, when using long life coolants.

 

Tom, I've owned 2 6.9's in the last 12 years....now I understand 6.9's are not prone to cavitation, but I just added a bottle of Ford diesel coolant additive every year as part of a preventance maintenace program. 7.3's on the other hand are prone to cavitation and test strips might be the proper way to go but for the price of the Ford diesel coolant additive, put in a bottle, and in dought, put it in twice a year.

 

From what I've read, you need a low silicate antifreeze astm 4985. Most antifreezes around here are astm 3306. I usually use Texaco Heavy Duty. I think the test strips need to match the coolant additive, but I'm not sure. I read somewhere that napa kool and DC4 are different and the DC4 is supposed to be better. Of course, I'm sure there are lots of people that use any antifreeze and just dump some sca in it and are fine for thousands and thousands of miles.

 

If you're using napa cool, you need napa coolant test strips. Other sca's [supplemental cooling additives] require additional testing. The simple answer is, sca's are a sacrificial layer on your coolant passages of your engine block, protecting the block from being eroded by cavitation, caused by the diesel combustion process, based on information people on this web site have shared.

 

a little hint that really helped my 7.3 idi is a bottle of Redline diesel water weter.it helps the coolant stick you could say to the coolant passages.i think most of that additive stuff is just snake juice as my dad calls it.this stuff made a noticable difference on the gauge.that and we have really herd water where I live.a freind of mine gose as fare as useing distilled water.what ever diff that makes?

 

This a bad subject. There are so many options out there and they are really broken down to two types. Longlife which is an organic ACID based and convention ethylene glycal that is alkaline. Now long life is ethylene glycal but the acids in it don't do well with "old" stuff.

One problem is all of the colors. The last I heard on this subject was that SAE, society of automotive engineers, was trying to get abunch of these colors eliminated by making manufactures stay with a few.

You will be fine by using conventional coolant and an additive like DCA4 and use Fleet guard test strips. The deal with Fleetgaurd test strips is that they will check other brands but other brands won't check Fleetgaurd DCA4 or now 5. Fleetgaurd had an additional additive that the other brands didn't have. I can't remember what it was, it has been awhile.


If you don't get pre-mixed 50/50, you WANT to use distilled water. Wether it be from Wal-Mart for 50 cents agallon or you catch rain water. Don't use tap water. That is what causes most of the deposites in your coolant system. Put some tap water in a pan on the stove and boil it down. What you will find in the pan is what stops up coolant passages.

 

The 6.9 is less prone to cavitation than the 7.3 because the cylinder walls are thicker.
But all diesel engines are prone to cavitation because of the increased cylinder pressure during the combustion stroke of the engine.

Silicates are added to regular antifreeze to protect the aluminum engine and radiator parts. There are no aluminum parts in the IDI cooling system or engine. The SCA can cause the silicates to precipitate out of the coolant and form a silicate gell deposit to form in the radiator.
This is a lot like the cold remedy commercial, why take medicine that treats for symptoms you don't have. Why treat your engine for components it don't have.

So you may run the 6.9 and probably will have nothing to worry about.
But down the road, you may want to rebuild the 6.9 and when you bore the cylinder you may bore into a cavitation hole that had not made it to the cylinder yet. But once you bore into the hole, the block is junk.

As catfish said, the minerals in tap water cause most of the deposits in cooling systems, again why add problems that can easily be avoided.

 

I think walmart now carries a 50/50 antifreeze for the diesels I think made by fleetguard for like regular tractor trailors and it has all it's sca's etc... anyways I'm pretty sure that the coolant life was some crazy number like 500,000 miles or something like that, I'll have to go back to that one walmart they had it in and double check it but either way I'll still be using it when I do my coolant change, I think if you use this stuff to fill your entire system there is no need to periodically check your coolant w/ test strips.

 

never use tap water in your engine or battery!


The deposits that form from tap water not only do your radiator in but also start the cavitation spot on the cylinder walls.

Farm tractor example, Fresh rebuilt to a JD 2940 5.9 (not Cummins!) engine after 10,385 Hrs ind. on clock. Wet sleeve motor, Radiator filled with 50/50 antifreeze distilled water Deere treatment added. test run/ start seat in process at dealer for 4 hrs. on dino. no leaks, runs strong!!!!!!! Delivered back to farm. goes to field work, A root from a tree along hedge row snags and removes bottom radiator hose, All coolant lost. No Problem it is summer so farmer refills radiator w/ his milk house tap water carried to tractor, No chance of freezing in May, Tractor put right back to working hard plowing and discing fields. then haying.

235 hours of use later on hr meter, farmer calls and is Upset, "COOLANT" is being blown out of radiator!!!!!!!!!!
Upon draining the system for rebuilding again we find "COOLANT" is straight water!!! ask history, find out about coolant lose/root and refilled w/ Tap water, I don't remember what the hardness tested after all the deposits on the cylinders walls but was still high. # 5 cylinder had a cavitation hole threw it. in 235 hrs of running!!!!!!!!!!!!!! Deere out of kindness covered 1/2 of the cost of second rebuild. farmer paid labor and learned a lesson. He was still a good customer of mine 3 yrs later when I left that Dealership. That was the only cavitation I saw in a green motor in 11 yrs. of sales.

The deposits help identify the hotspots for the steam jetts to bore threw the steel.


Its your motor, use whatever you feel comfortable with. I have 2 gallons of distilled water in my shop, just incase I need some.

 

Cool6.9dieselguy,
Actually you still need to check the SCA levels every three or four months.

The SCA deposits a sacrificial layer on the cylinder walls in the coolant passages.
If there is not enough SCA to do this, you can still wind up with a cavitated block.

 

I'm not 100% knowledgeable on the subject but I'll let you know what this company has to say that makes it

 

I thought that was what I was showing by the above example, Treatment and distilled water, plus testing.

 

Hey all,

What is the best action to take if you do not know what previous coolant was used? In my case I have an 88 with a 7.3 that I bought last year. It has 160,000 km's on it.

I "tested" the coolant with a hydrometer and topped it up when I bought it, but now I have drained it all out to replace my water pump. Since this enatails bit of work, I pulled the rad out and flushed it well.

The sand and scale discussed here was there. I will now put it back together along with a new thermostat. My plan was to use Diesel grade coolant and distilled water.

Since I have no real idea of cavatation development or what has been done over 19 years, is this all I should do? Is adding SCA's too late?

Thanks.

Das Ungetum.