cavitation???
New User
Joined: Jul 2004
Posts: 7
Likes: 0
From: Petaluma, CA
Dave- I've been reading this forum for about a week now and have already come to the conclusion that you're a bank of info when it comes to these engines. I went to the link you posted for ShopDiesel and have one question: You recomend using VC-7A coolant with VC-8 additive. On their site if you go to the VC-7A link it warns "DO NOT MIX WITH GREEN COOLANT", so common sense tells me VC-7A isn't green. Right? But then on the VC-8 link it warns "DO NOT USE WITH ANY OTHER COOLANT EXCEPT GREEN". Please clarify if you will. Also, what do you know about the Fleetguard ES COMPLEAT Extended Life Antifreeze Coolant Precharged with DCA4 other than the fact that it's expensive.
Originally Posted by Dave Sponaugle
There are addatives you add to the coolant to prevent this. The ones with this problem are the ones with out the addative in them.
You run a low silicate heavy duty antifreeze and a Supplamental Coolant Addative (SCA)
Never run the green Prestone stuff or another regular auto antifreeze.
I run Ford Heavy Duty antifreeze and SCA.
If it cavitates, you are looking at a complete rebuild, bunches of $$$$ ( read as dollar signs to the 4th place left of decimal)
To do a complete change you need 4 gallons of antifreeze (VC-7A) and 2 bottles of (VC-8) SCA (Ford part numbers)
Flush the cooling system out several times, the two antifreezes (regular auto and heavy duty diesel) are not compatible.
Ford also sells test strips to test for proper levels of SCA's that will tell you if the addatives were used in the cooling system before you added what ever you added.
You must test the antifreeze every couple of months to make sure you have the proper level of addative in it. To much is just as bad as not enough.
I personally check it every other month.
If you smell the sweet smel of antifreeze in the exhaust pipe, that is bad, but it could be a head gasket leaking. That is still not good, but it is lots better than cavitation. Hoses, heater cores, soft plugs, block heaters, water pumps and oil coolers are also possible culprits for leaks.
Don't jump ship just yet, you may be just fine. First you need to check for SCA's and find out if you have a leak or not. Also if you added regular antifreeze you need it out and a good heavy duty antifreeze with addatives back in, tomorrow is not to soon if you possibly can.
You run a low silicate heavy duty antifreeze and a Supplamental Coolant Addative (SCA)
Never run the green Prestone stuff or another regular auto antifreeze.
I run Ford Heavy Duty antifreeze and SCA.
If it cavitates, you are looking at a complete rebuild, bunches of $$$$ ( read as dollar signs to the 4th place left of decimal)
To do a complete change you need 4 gallons of antifreeze (VC-7A) and 2 bottles of (VC-8) SCA (Ford part numbers)
Flush the cooling system out several times, the two antifreezes (regular auto and heavy duty diesel) are not compatible.
Ford also sells test strips to test for proper levels of SCA's that will tell you if the addatives were used in the cooling system before you added what ever you added.
You must test the antifreeze every couple of months to make sure you have the proper level of addative in it. To much is just as bad as not enough.
I personally check it every other month.
If you smell the sweet smel of antifreeze in the exhaust pipe, that is bad, but it could be a head gasket leaking. That is still not good, but it is lots better than cavitation. Hoses, heater cores, soft plugs, block heaters, water pumps and oil coolers are also possible culprits for leaks.
Don't jump ship just yet, you may be just fine. First you need to check for SCA's and find out if you have a leak or not. Also if you added regular antifreeze you need it out and a good heavy duty antifreeze with addatives back in, tomorrow is not to soon if you possibly can.
Post Fiend
Joined: Nov 2003
Posts: 21,285
Likes: 15
From: Nutter Fort, WV
Fleetguard is good stuff.
If you figure the coolant and SCA each way, the Fleetguard ES is actually cheaper by a couple of cents.
VC7A is Gold
I gotta go read the bottle of VC8 again, I may be doing an antifreeze change tomorrow.
That is not on the bottle, another Ford recommendation for my new motor.
Why do you have to check and research every move you make these days.
Think I am changing to DCA4 anyway.
Thank you for pointing that out to me, I just added to my knowledge base.
If you figure the coolant and SCA each way, the Fleetguard ES is actually cheaper by a couple of cents.
VC7A is Gold
I gotta go read the bottle of VC8 again, I may be doing an antifreeze change tomorrow.
That is not on the bottle, another Ford recommendation for my new motor.
Why do you have to check and research every move you make these days.
Think I am changing to DCA4 anyway.
Thank you for pointing that out to me, I just added to my knowledge base.
New User
Joined: Jul 2004
Posts: 7
Likes: 0
From: Petaluma, CA
What's the best / appropriate way to do a coolant flush and change? When you say flush the system out a couple times are you talking with water, cleaner, or new coolant? On the ShopDiesel site they sell Fleetguard® Heavy Duty Cooling System Cleaner/Restore at a price of $25.33 per gallon. Not only is that expensive, but they don't say how much you have to use or clearly how you go about using it (if you read the link for the product you'll see why I say "clearly). I plan on starting from scratch with the truck I just bought because I don't know how the previous owner maintenanced it or how much he knew as far as cavitation goes. Thanks
New User
Joined: Aug 2004
Posts: 10
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There's some confusion here about exactly what is cavitation. The full explanation is somewhat long-winded, but I'll try to be clear and concise.
Caviation is a hydraulic process, not mechanical or chemical. Negative pressures act on the coolant even in a pressurized system such that air bubbles are generated in the liquid (it appears to boil) but in a very localized manner, such as behind the vanes of the water pump. (Sorry, it doesn't even need to be negative pressure, it could still be positive but just at a pressure lower than the rest of the system.) When these bubbles move out of this lower pressure area into a higher pressure area elsewhere (somewhere in the block) they collapse. But they do so with great violence, almost like an impact. It's this localized collapsing and subsequent hammering that breaks down the nearby metals. As coolant temperatures increase, risk of cavitation increases because the liquid has more energy in it to 'boil'. Higher pressures reduce cavitation so cooling systems are pressurized. Cooler temperatures also reduce cav'n. Also, water pumps usually pump cool coolant into the engine, rather than hot coolant out of the engine.
Now, I don't know why or where Ford diesels seem to be stricken with cavitation problems. Can anyone enlighten me on this?
Mopartom
Caviation is a hydraulic process, not mechanical or chemical. Negative pressures act on the coolant even in a pressurized system such that air bubbles are generated in the liquid (it appears to boil) but in a very localized manner, such as behind the vanes of the water pump. (Sorry, it doesn't even need to be negative pressure, it could still be positive but just at a pressure lower than the rest of the system.) When these bubbles move out of this lower pressure area into a higher pressure area elsewhere (somewhere in the block) they collapse. But they do so with great violence, almost like an impact. It's this localized collapsing and subsequent hammering that breaks down the nearby metals. As coolant temperatures increase, risk of cavitation increases because the liquid has more energy in it to 'boil'. Higher pressures reduce cavitation so cooling systems are pressurized. Cooler temperatures also reduce cav'n. Also, water pumps usually pump cool coolant into the engine, rather than hot coolant out of the engine.
Now, I don't know why or where Ford diesels seem to be stricken with cavitation problems. Can anyone enlighten me on this?
Mopartom
Senior User
Joined: Feb 2004
Posts: 152
Likes: 0
From: Utah
From what I understand the older IDI's especially the 7.3 are more likely to have cavitation problems because of the cylinder wall thickness. The 7.3 was "born" by boring out the older 6.9 which took a fairly thin cylinder and made the problem even worse. Because the walls are thinner then other engines they 1) can vibrate more causing larger and more frequent vapor cavities in the coolant and 2) less steel that the cavitation has to chew through to cause the a problem.
I've also been reading about "cavitation" for some time and have seen a number of really interesting explanations, Mopartom was by far one of the most accurate. But I thought I'd add my 2 cents anyway.
One of the things that I think confuses a lot of people is the term "air bubble" while its not quite wrong it implies "air" is getting into the system which its not. The bubbles are still 100% water, but because of the pressure & temperature the water has become water vapor (boiled) as soon as these pockets of water vapor reach an area of higher pressure the vapor returns to the liquid phase and the "bubble" of vapor implode with tremendous force and can eat away at steel (or anything else) faster than a good sandblaster.
I guess I could also add that the difference between air getting into a water pump (not necessarily an automotive water pump) (veining) and a pump cavitating due to low pressure are two completely different modes of failure. However, most of the time people don’t care because either way the pump is ruined, and the symptoms can often look fairly similar.
I've also been reading about "cavitation" for some time and have seen a number of really interesting explanations, Mopartom was by far one of the most accurate. But I thought I'd add my 2 cents anyway.
One of the things that I think confuses a lot of people is the term "air bubble" while its not quite wrong it implies "air" is getting into the system which its not. The bubbles are still 100% water, but because of the pressure & temperature the water has become water vapor (boiled) as soon as these pockets of water vapor reach an area of higher pressure the vapor returns to the liquid phase and the "bubble" of vapor implode with tremendous force and can eat away at steel (or anything else) faster than a good sandblaster.
I guess I could also add that the difference between air getting into a water pump (not necessarily an automotive water pump) (veining) and a pump cavitating due to low pressure are two completely different modes of failure. However, most of the time people don’t care because either way the pump is ruined, and the symptoms can often look fairly similar.
New User
Joined: Nov 2003
Posts: 13
Likes: 0
I Have Not Posted In A While And Today As I Was Checking The Board As Usual, There Was A Picture Of Mr T On Top Of The Page Promising Great Pain If I Did Not Post! Firecapt I Know How You Feel About Finding Out About Cavitation After The Purchase. I Bought An 88 For 2,300 Then Sank Another 1,200 On Everything From Pickup Lines In The Tank, Batterys Alternator, Regulator, Starter, Fuel Rail Ac Even Tint A Seat Cover And The Cig Lighter, Only To Find Out That All The Money And Hard Work May Have Been On A Lemon.thanks To The Very Diesel Smart And Helpful People On This Forum I Made A Trip To The International Dealer And Got The Correct Coolant And Additives. The Truck Only Had 69000 Miles So Maybe Its Ok, But The Thought Of Those Little Pinholes Just Wont Go Away. Good Luck On Your Truck, And To All The Guys On This Forum Thanks For All The Advice. John
New User
Joined: Aug 2004
Posts: 4
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From: Washington
Wow
Guys just wanted to say a big thanks also. I bought my 93 a few months ago and had no idea about the cavitation thing. So now I know and I know what I'll be doing very soon. Thanks again, John
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Posting Guru
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A better descriptive word would be. When the vapour bubble implodes. It can chip a very small pieced of metal off. This was mainly a problem on wet sleeve engines. The special coolant actually puts a sacrificial layer between the vapor bubble and the wall of the cooling passage. Kindof like a bullet proof vest for diesels. It is direly important with the 7.3 to make sure the coolant is changed frequently and that you have the proper additive package. Dont be cheap. You will pay for it by hydrolocking #8.
While your at it. Change your brake fluid and power steering fluid. Cause I know youve been neglecting it.
While your at it. Change your brake fluid and power steering fluid. Cause I know youve been neglecting it.
Senior User
Joined: Feb 2004
Posts: 152
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From: Utah
The diesel engine has a much higher compression ratio, more pressure in the cylinders causes more vibration on the coolent side of the walls. It is the vibration (quick movement) that causes the low pressure areas to form, and then break. Thats what causes the coolent to cavitate.
In a gas engine (at least most of the time) the vibrations don't cause cause the pressure to drop low enough (vapor point) to form vapor bubbles.
In a gas engine (at least most of the time) the vibrations don't cause cause the pressure to drop low enough (vapor point) to form vapor bubbles.
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Joined: Mar 2003
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Originally Posted by scottie2hottie
I see- thanks for clearing that up. Just out of curiosity, which engine tends to run hotter, diesel or gas?
Thanks again, sorry for being diesel-dumb
Scott
Thanks again, sorry for being diesel-dumb
Scott
The thermal efficiency is also why a diesel is less likely to overheat.
A diesel does not use one air to fuel ratio like a gasoline engine. 14.7 to 1 is the best for gasoline. They call it stochiometric. While a diesel can run 100 to 1 to 20 to 1 during normal operation. The more fuel you stick in a gas engine the cooler it runs. The opposite is true for diesels. If you tried to run a gasoline engine at 100 to 1 you would melt the pistons.