what is cavitation, and what can i do about it, or how can i avoid it?

 

Cavitation is a chemical corrosion of the inside of the cylinder bores (from the water jacket side). There is an additive to put in the cooling system that can be bought from either the Ford or Navistar dealers. Make sure when you change your coolant you use this additive.

 

The additive you need is FW-16. You also need the test strips to check the amount of additive required. Good luck.

Les

 

If you already have it your motor is junk and the block can no longer be reused, i dont know why the dont call it porousity since thats what it is are these two words the same or am i wrong saying the block is porous?

 

I always thought I knew the definition of cavitation, but it seems the only definition I knew was the one made popular by the movie "Hunt for Red October". I didn't know it was a fancy word for rust or pitting till I looked it up in the dictionary a couple of days ago.
Anyway, does anyone know why this is a problem with the diesels? Is it poor metallurgy? Is it somehow linked with the cooler running nature of a diesel engine?

DannyP
89 F-150 4x4 former EFI I-6 now carbed 351W, Edelbrock heads,cam,intake,carb.
MSD 6A, ZF, Sterling 10.25 with 3.55L's.

 

This is how it was explained to me:

Cavitation is more noticed on hard worked diesel engines that have had poor cooling system maintenance. When a diesel engine starts to work hard (Pulling a trailer, or heavy load) the cylinders will rapidly rise in temperature. The sudden rise/fall in temperature begins to weaken the outside of the water jacket and will cause it to pit or erode. That is why the ford engines have oil cooler nozzles that spray oil in the middle of the pistons. Otherwise the pistons will do the same thing. A cooling system additive is used to stop this by surrounding the water jackets with a microscopic protective coating.

 

Cavitation was explained to me a little differently. Due to the high compression in the cylinders, the cylinders expand and contract quickly and gas pockets in the coolant attacks the outer side of the cylinder walls. The additive puts a protective layer on the cylinder walls to prevent cavitation. The PSD has thinner cylinder walls than other diesels so coolant maintanance is more important on PSD's than other diesels. I'm sure there is more to add but who knows.

Les

 

[font size="1" color="#FF0000"]LAST EDITED ON 24-Feb-01 AT 10:04 PM (EST)[/font][p]Cavitation and porosity are NOT the same. Porosity occurs during the casting process. Cavitation is a change in the metalurgy caused by hot spots (not enough coolant flow) in certain areas. On the 6.9/7.3 IDI engine it is caused, in part by the cylinders too close together (a design problem). The IDI engine was a converted gasoline engine and the bore spacing was a little closer than what they should have been. The 2 previous posts explain it about the way it was explained to me

 

Thank you for that clarification your right the porousity i have always know has always happened during casting your explanation makes sense, thank you

 

The 6.9/7.3 is converted from a gasoline engine? I didn't know this. Please elaborate.

DannyP
89 F-150 4x4 former EFI I-6 now carbed 351W, Edelbrock heads,cam,intake,carb.
MSD 6A, ZF, Sterling 10.25 with 3.55L's.

 

Thats beating a dead horse DannyP i think they already had this argument, i think it maybe untrue , yes could someone enlighten us on the 6.9/7.3's former gas engine struggles / woah's ?

 

If you have much faith in Ford, I would tend to believe the engine is not a converted gas. I'll admit I have no knowldege on the subject, excpet that GMC converted a 350 gas engine to diesel, and the restults were not very good. I myself believe the 6.9/7.3 IDI are not converted gas, Ford SHOULD have learned from the mistake made by GMC years before.

Logan

 

Ford never produced any diesel engines it would have IH that would have learned their lesson but thats not the case

 

For Danny P., Otto, and Logan 85: The 6.9/7.3L IDI Diesel engine, manufactured by Navistar (formerly International Harvester) was previously known as the "MV8" which were 404 cubic inch and 446 cubic inch (6.9 Liter) gasoline engines that were produced starting late in 1974 and running through late 1981. It was engineered as an exhaust emission engine but the Nixon administration relaxed the exhaust emission standards for trucks which instantly made our engine unnessary and too expensive along side of old technology. There was also supposed to be a 485 cubic inch version but as far as I know we never produced any. We built a total of 120,661 during those years then shut it down to convert the tooling to manufacture the 6.9. There was very little tooling changes to the manufacturing lines except for the cylinder head line which was completely retooled. When it was all done, what we had was an MV8 with Diesel heads and a rotary injection pump in the valley. At the time, International Harvester had plowed some heavy duty money into some research and developement projects at the same time that they put the union out on strike for five and one half months and shortly thereafter the economy went sour (the worst recession since the Great Depression) and our cash flow dried up over night. We put the 6.9 into production for $39 million. That engine, rising out of the ashes of the MV8, is single handedly the reason we are still in business today. Thanks for asking!

 

Otto, I knew that Ford didn't produce the 6.9/7.3L, instead Ford had to accept the design, so I consider accepting a design about the same as building a design(but I know accepting a design and building a design are different). What about the 7.3L I heard it was simply a bored over 6.9L, is that true?

Logan