I have always read and learned that cavitation was exhibited in lined engines.

It is caused by 'dissimilar metal corrosion' if you expose 2 different metals to one another they corrode, period.
That is the primary cause of engine pitting, aka cavitation.

If you search for diesel engine cavitation 95% of the results will expose this as a liner issue.

 

dissimilar metals corroding when in contact is called galvanic corrosion not cavitation.

 

Baldwin Filters
http://www.constructionequipment.com...CA6256027.html

Harvard University
http://adsabs.harvard.edu/abs/2003ASAJ..114.2386C

Dissimilar Metal Corrosion
http://www.assda.asn.au/asp/index.asp?pgid=18533



This is primarily why marine engines and equipment have sacrificial anodes (zinc) added. The Noble metals are protected by the anode.

 

Please read up on galvanic corrosion and you will see that it is very much due to the liner being a different metal than the block and then adding the conduit of water promotes corrosion.

****

Galvanic/Dissimilar Metal Corrosion
Contact between dissimilar metals occurs frequently but is often not a problem. The aluminium head on a cast iron block, the solder on a copper pipe, galvanising on a steel purlin and the steel fastener in an aluminium sheet are common examples. What causes galvanic corrosion?
For galvanic or dissimilar or electrolytic corrosion to occur, three conditions must be met:

• the metal join must be wet with a conductive liquid
• there must be metal to metal contact
• the metals must have sufficiently different potentials

Wetting the join
The conductive liquid or electrolyte could be rainwater or even water from condensation. The greater the conductivity the more severe the galvanic effects. Salt or industrial pollution significantly increases the conductivity of water so galvanic effects are normally more severe near the coast or in heavy industrial areas. Low conductivity, pure rainwater will only cause slight galvanic effects. One complication is that during evaporation, water films become more conductive so initially benign water may cause quite active galvanic effects as the liquid in the crevice under a bolt or clamp becomes more concentrated. Water may be excluded by design or the use of adhesive sealants.
Metal to metal contact
Galvanic corrosion can only occur if the dissimilar metals are in electrical contact. The contact may be direct or by an external pipe or wire or bolt. If the dissimilar metals are insulated from each other by suitable plastic strips, washers or sleeves then galvanic corrosion cannot occur. Paint is not a reliable separator from direct contact although painting all of the noble metal is quite effective. Painting the active metal causes drill holes at coating defects.

 

I fully understand what galvanic corrotion is and how it works. that is not the cause of liner/metal pitting due to cavitation. that first and second article you posted pretty much sums up what I've been trying to say. the power stroke of the piston creates a frequency that opens tiny air bubbles agains the cylinder wall. that implode with force great enough to destroy the metal it is touching. The additive package in ELCs prevent bubbles from forming at all.


now the additive package also prohibits any corrotion the the coolant. thats a whole separate problem from cavitation.

I guess when I was in school for 4 years learning to become a HD mechanic they didn't explain these principles to me very well because theres obviously something I'm missing here.

 

What I've been told numerous times is that blocks built with cyliner liners are the most prone.Not bored and finished blocks.Too late in the day now but I will do some research on the International 6.9 etc.to see why it was so prone to it. I just know the Cummins engine used in Dodge trucks has never been prone to this.

 

The bubbles are forming because of the electrical current created, the bubbles are the manifestation of corrosion.
That means that are representative of real-time corrosion taking place.

Pitting is a sign of corrosion, in these cases the word cavitation is used; just like the galvanic corrosion and dissimilar metal corrosion. they are the same and mean the same.

iron rusts
typically aluminum gets a white chalky substance but some do pit also
Steels can rust and/or pit depending on the alloy content

These are all forms of corrosion (rust, chalk, pitting).

The bubbles are simply the visible steps of corrosion occuring, just like in a battery.

We have anodic disassociation and the presence a cathodic metal causes what is known as autocatalytic process.


TRUK- man the simple answer is in your 2004+ truck you should search for a HOAT antifreeze and no additive pack is needed.

 

I don't know what to say bud, That's not what we were taught in school. I am a HD mechanic and the Government of Alberta curriculum teaches something different.


So either Alberta's got the system wrong or you're wrong. I only know what I've been taught.

 

This was a BIG problem in Ford 6.9 and 7.3 IDI engines. An anti cavitation additive had to be used. It's my understanding that the problem was solved somewhat in later years. It is however a problem, primarily if not exclusively known to effect LINED engines not bored ones, hence never hearing of it being a problem in the bored not lined Cummins.
Joe

 

You outta read your links much more closely............ that baldwin and the harvard links state EXACTLY what I have been saying. Cavitation is a problem unto itself. Cavitation is NOT another word for galvanic corrosion. Cavitation IS cavitation. bubbles formed & destroyed by the sonic vibrations created by the piston passing by on the power stroke. this is a fact, not something I heard from some guy or read on the internet.

and the liner vs bore block is kind of moot. as all diesel engine can get it. it may cause catastrophic failures much more often in wet liner engines, but parent metal cylinder engines are not immune to the problem. as CLEARLY shown by the 6.9 and 7.3. 5.9 Cummins may not have failures from it, but that does not mean its not happening in the engine. it just means theres enough metal there to allow cavitation to occure without failure.

{QUOTE}
Wet-Sleeve Cavitation

Wet-Sleeve Cavitation
In a wet-sleeve cooling system, antifreeze additives create a barrier between the engine's sleeves and the small bubbles that form in the coolant next to the sleeves, the result of pressure differentials. When the normal vibration of the sleeves causes the bubbles to implode, they do so with great violence and can create tiny cavities in the surface of unprotected sleeves. Left unchecked, this "cavitation" process (a leading cause of engine failure) can create holes in the sleeves and allow coolant to leak into the cylinder. Fully formulated conventional antifreeze uses nitrite, which coats the sleeves, to protect against cavitation. Organic-acid-technology antifreeze uses chemicals that plate sleeves with a thin protective layer, but these formulations also may contain nitrite.

Illustration adapted from Baldwin
{/QUOTE}

 

It's yet another ford issue not a Cummins issue. It really only happens to wet sleave blocks. The ford have the addiatives not the Dodges