Somebody please tell me about this:

SCA's are sppplimental coolant addatives, that prevent cavitation in diesels.

What brand do you use and where do you get it?

Thanks!

 

I use NapaKool and their test strips.

Others say usa SC4 but they have never been able to tell me where to buy it. I'm beguning to think it's in certain anti-freeze and you can just get an addative that has it.

 

Fleetguard all the way. I used DCA but they sell SCA.

 

Yep, I use Fleetguard just because it's easy for me to get at Tractor Supply and it already has the SCA in it. They use Pencool IIRC.

 

motorcraft fx-16 any ford dealer

 

DCA 4 is the Fleetguard name for the SCA additive they have test strips too available at IH/Navistar truck and tractor stores.

http://www.fleetguard.com/pdfs/produ...es/LT15626.pdf (test strip)


The Ford product is now called VC8 no longer the FW-15 or FW16 as you may find in some articles.

TSB 93-6-11 Cooling system-7.3 diesel.

Coolant additive to prevent cylinder wall porosity-engines built before serial number 981059.

Motocraft FW-16 & Fleetguard Test Strips

 

Finally some sources!

Do you have any idea when the ser# 981059 motor was built?
Am I to take that to mean that they quit having the electrolysis/cavitation issues at some point?

I have heard of 7.3L Powerstrokes having this problem to, albeit a lot fewer.

 

It is call linear liner cavitation, All suppment coolant additive (SCA) is is nitrate. all it does is change the surface tension of the coolant so it can not form the bubbles that form along the heat line on the cyl. wall so there for the bubbls can not implode which prevents the cavitation.

so any way to change the surface tension will stop the problem.

ALL DIESELS NEED NITRATE

 

It must be a long way back of my engine...... mine is 073312*

 

Thanks!! Guess I'll head to NAPA and get some.

 

That's what I've always understood to cause the problem.
A bubble forms on the cast surface and pops when the cyl. "fires" taking away a tiny particle of metal everytime.

 

Well that is close, the bubbles form because of a super heated linear spot on the cly. wall caused by the connecting rod at an angle pushing the piston against the cyl. wall. the bubbles form on that line because the coolant boils. the surface tension of water causes the bubbles to form and hold together long enough untill the pressure becomes to much then they IMPLODE against the cly wall causing pitting.

ALL diesels do this even the 6.9 but because the cyl walls are thicker it distributes the heat in a wide line so cavitation is not as bad and it takes longer to eat though.

were this problem is most noticeable is in wet linered engines.

 

I give a slightly different cause of cavitation.
It is a diesel specific problem and it affects all diesels.

Actually it is the cylinder wall flexing.
During the combustion stroke the cylinder wall flexes outslightly into the coolant passage causing a high pressure area.

Then after the combustion event, the wall flexes back in toward the piston, which causes a lower pressure area to be formed against the coolant side of the cylinder wall.
The low pressure area causes bubbles to form since water boils easier the lower the pressure is.

The next combustion event causes the cylinder wall to run into the bubbles as they are collapsing, which causes a small chunk of the cylinder wall to be erroded by the violent bubble collapse.

This cavitation process is a problem on all high compression engines.

The NA IDI is 21.5 to 1 for the 7.3, 22.5 to 1 for the 6.9.
Turbocharged engines get up into the 30, 40, 50 or 60 to 1 range depending on the base compression ratio and the amount of boost.

The difference between the 6.9 and 7.3 cylinder wall thickness means the 6.9 has less flex than the 7.3 which has thinner cylinder walls.
Also the greater thickness of the 6.9 cylinder wall means the cavitaion has more metal to eat before it is a problem.

SCA's work by depositing a sacrifical layer on the inside of the block.
The cavitation eats the sacrificial layer instead of the cylinder wall.

That is the reason you need to maintain a specific level of SCA at all times.
To much SCA is just as bad as to little.
To much causes either to much to be deposited or it actually precipitates out of the coolant blocking coolant passages.
To little leaves the block exposed to the cavitation process.

 

That would help explain why the Cummins 6BT doesn't ever manifest the problem.
Even thicker cylinder walls and less "side load" because of the in-line cylinder lay out.
Cummins makes a big deal out of using the right coolant but not the "addatives".

The SCA sacraficial explanation makes sense to me.
I think, a long time ago, I read something in my Cummins research about the surface tention thing to keep the bubbles out of the coolant too.
There night be something to both "theories".

 

I think you will find that the correct Cummins coolant does contain SCA's.

In the larger engines with wet sleeves the SCA's were no big deal.
You just changed liners when you had a problem.

With modern blocks that do not have removable liners, it is much more of an issue.

Mack, Cat, Cummins, Detroit Diesel, IH and others all recommend a specific coolant, or a coolant minimum standard.
That is to insure that SCA's are used.
Side load has nothing to do with cavitaion.
The extreme pressure on compression and combustion strokes is the culprit.

Fleetguard is a Cummins subsidiary company.

Evans waterless coolant is the only antifreeze that I know of that does not recommend SCA addatives.
But I also don't know of any manufacturers that have approved Evans coolants.

Here is an excellent article that was written for oilburners that explains cavitation and SCA's with some pictures and drawings.

Cavitation Article

Here is another article from Arrowhead radiators about cavitation.

Cavitation,_SCAs_and_the_Proper_Maintenance_of Diesel_Engine_Cooling_Systems