BBQ tick - another attempt to understand

[Condor1970]

I highly doubt there is any oil "flashing" or "boiling/vaporization" going on as the oil comes out of the bearing since going through the bearing would have to raise the oil temperature from ~200F to over 450F. If you study up on journal bearings the normal oil temperature rise as it gets squeezed and sheared by going through the bearing is around 30~40F ... not a rise of 250+F. (200F to 450+F).

In order for the bearing to raise the oil temperature inside the bearing to 450+F, the clearance would have to be very very small, and besides if oil the localized oil temperature is raised to 450+F the MOFT will go to zero and the bearing will literally smoke itself with metal-to-metal contact. That's why I don't believe that theory.

You do realize that oil cavitation due to a rapid drop in pressure is the same thing. It's not flashing in a sense of reaching ignition, but is boiling / cavitating from a rapid change in pressure. That's what causes cavitation...a rapid pressure drop.

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[GT Pony]

You do realize that oil cavitation due to a rapid drop in pressure is the same thing. It's not flashing in a sense of reaching ignition, but is boiling / cavitating from a rapid change in pressure. That's what causes cavitation...a rapid pressure drop.

Not really the same thing because cavitation is tiny trapped air bubbles that are imploding due to a decrease in pressure ... cavitation is not the result of oil heating up and "flashing" or "boiling", so it's not the "same thing".

Like I said, oil is not "flashing" or "boiling" inside journal bearings or when it exits the sides of the bearing. The oil would have to be over 450F to do that, and there's no way it gets that hot going through a bearing ... if it did, the bearing would fail in short order.

 

[Condor1970]

Not really the same thing because cavitation is tiny trapped air bubbles that are imploding due to a decrease in pressure ... cavitation is not the result of oil heating up and "flashing" or "boiling", so it's not the "same thing".

Like I said, oil is not "flashing" or "boiling" inside journal bearings or when it exits the sides of the bearing. The oil would have to be over 450F to do that, and there's no way it gets that hot going through a bearing ... if it did, the bearing would fail in short order.

I never said it was heating up. Liquids can flash into vapor just from a rapid pressure change. It can actually be calculated using Boyles Law with a Pressure Temperature Relationship equation. It's been years, but we studied this a lot in Mechanical Engineering class. Same thing with a ships screw. The cavitation on the trailing edge of the blades, is NOT air bubbles. It's actually water vapor that expands and contracts due to a rapid change in pressure from rotating too fast. Same goes for the oil. Those vapor bubbles are NOT air bubbles, it's oil itself temporarily flashing to a vapor then collapsing back into a liquid.

Even the definition from Waukesha Bearing has the same understanding. It's oil vapor, not air vapor. The first and most common way to minimize the effects, is to increase oil pressure to prevent vapor bubbles from forming. Reducing Running Clearance can also be done, but with bearings that are in spec, that option is not available.

Cavitation Erosion
Cavitation erosion is an impact fatigue attack caused by the formation and collapse of vapor bubbles in the oil film under conditions of rapid pressure changes during the crank cycle in internal combustion engines. The harder the bearing material, the greater its resistance to cavitation erosion.

Addressing the Damage
Continued use of the affected bearings will depend upon the severity and extent of the cavitation erosion.

To limit or reduce damage from cavitation erosion, several options should be investigated:

• Increasing the oil feed pressure
• Modifying the bearing groove, blending edges or contours of grooves to promote streamline flow
• Reducing running clearance
• Changing to a harder bearing material

 

[GT Pony]

Yes, I know what cavitation is, I've posted the same info many times before and links to papers that talk all about it. Point is that aerated oil can certainly aggravate the likelihood of cavitation of oil.

If the ticking is caused by cavitation, them maybe it's because some Coyotes aerate the oil more than others for some reason. There was talk about an O-ring on the oil pickup tube possibly leaking air and causing oil aeration on some Coyotes.

 

[Condor1970]

Yes, I know what cavitation is, I've posted the same info many times before and links to papers that talk all about it. Point is that aerated oil can certainly aggravate the likelihood of cavitation of oil.

If the ticking is caused by cavitation, them maybe it's because some Coyotes aerate the oil more than others for some reason. There was talk about an O-ring on the oil pickup tube possibly leaking air and causing oil aeration on some Coyotes.

I see what you're getting at. However, if the oil itself is Aerated, then using Ceratec would have no affect in solving the issue, since it's oil foaming and "Aeration" that's the problem, and not "Cavitation". They're 2 different things. Ceratec actually works because it changes the Cavitation behavior of the oils ability to flash into a vapor. If it was already foamed up from air, then Ceratec would do nothing to change that.

Also, if you have aerated oil getting sucked up through the oil pump, you can bet you'd probably have some other issues as well. Like erratic oil pressures, and/or even noise from the pump itself. Also, with Aerated oil, you would hear ticking and other noises from ALL the bearings, and not just the one. That would be a serious problem that WOULD cause damage to the engine, and you can bet Ford would have a serious TSB issued if that were the cause. There's no way they would allow hundreds of thousands of engines in Mustangs and F-150's to stay on the road knowing Aerated oil was destroying the engines en masse that are ALL still under warranty. That's a case where they would do the repair to prevent a much bigger warranty issue that would cost a heck of a lot more than just pulling an oil pan, and installing an O-ring. They wouldn't release an SSM saying it's "Normal", and no attempt should be made to fix it.

 

[GT Pony]

Ceratec actually works because it changes the Cavitation behavior of the oils ability to flash into a vapor.

There's absolutely no proof that Cetatec prevents cavitation ... there's even no proof that the ticking is even caused by oil cavitation. If you have proof that it's cavitation and 1.5% concentration of Ceratec makes the cavitation go away, then let's see the scientific testing and proof (ie, see through journal bearings monitoring the cavitation like the paper I linked earlier).

 

[Condor1970]

There's absolutely no proof that Cetatec prevents cavitation ... there's even no proof that the ticking is even caused by oil cavitation. If you have proof that it's cavitation and 1.5% concentration of Ceratec makes the cavitation go away, then let's see the scientific testing and proof (ie, see through journal bearings monitoring the cavitation like the paper I linked earlier).

Well, when you have the exact same noise coming from the diesel engines made by Chevy and Ford, and they say that's what it is, then it makes sense it's the same for a high compression V8 gas engine. Especially when the SSM says it's normal, and no attempt should be made to fix it.

And yes, it makes total sense that a solid lubricant will affect the cavitation properties of a liquid. This is commonly known in physics/chemistry.

 

[GT Pony]

BTW ... cavitation is the implosion of tiny trapped air bubbles trapped in the oil. I think if you could devoid the oil 100% of trapped air the possibility of cavitation would be nill.

https://www.valin.com/resources/articles/pop-cavitation-bubble-hydraulic-systems

"Cavitation, defined simply as the formation of bubbles in a liquid, can have detrimental effects on a hydraulic pump. In an incorrectly designed hydraulic system, a vacuum may form on the hydraulic fluid, pulling trapped air out of the fluid to form small bubbles."

A variety of factors within the system could produce such a vacuum. When fluid enters the hydraulic pump and is compressed, the small air bubbles implode on a molecular level."

 

[GT Pony]

Well, when you have the exact same noise coming from the diesel engines made by Chevy and Ford, and they say that's what it is, then it makes sense it's the same for a high compression V8 gas engine. Especially when the SSM says it's normal, and no attempt should be made to fix it.

And yes, it makes total sense that a solid lubricant will affect the cavitation properties of a liquid. This is commonly known in physics/chemistry.

Again, post up some links to backup your claim that Ceratec prevents cavitation, especially at a 1.5% ratio (150mm in 10 qts).

Those diesels are much higher compression than a gas powered Coyote.

 

[Condor1970]

BTW ... cavitation is the implosion of tiny trapped air bubbles trapped in the oil. I think if you could devoid the oil 100% of trapped air the possibility of cavitation would be nill.

https://www.valin.com/resources/articles/pop-cavitation-bubble-hydraulic-systems

"Cavitation, defined simply as the formation of bubbles in a liquid, can have detrimental effects on a hydraulic pump. In an incorrectly designed hydraulic system, a vacuum may form on the hydraulic fluid, pulling trapped air out of the fluid to form small bubbles."

A variety of factors within the system could produce such a vacuum. When fluid enters the hydraulic pump and is compressed, the small air bubbles implode on a molecular level."

Notice it said "Molecular" level. Not on the Macro level. If you had aeration on the level needed to produce a bubble big enough to make that much of an audible noise, you'd be in serious trouble. That oil would have to look like a banana smoothy to form AIR bubbles that big.

 

[Condor1970]

And who knows, even if some of that vapor is air, Ceratec may in fact affect the oils ability to release imparted air molecules as well. We know solids added to liquids do affect their ability to boil and vaporize. No reason to believe it wouldn't affect small amounts of air molecules in the oil as well.

 

[GT Pony]

Notice it said "Molecular" level. Not on the Macro level. If you had aeration on the level needed to produce a bubble big enough to make that much of an audible noise, you'd be in serious trouble. That oil would have to look like a banana smoothy to form AIR bubbles that big.

I've seen YouTube videos that showed aerated oil drained out of a Coyote - claimed it was the leaky pick-up tube O-ring. Ended up smoking the motor on a dyno run when the oil was aerated badly. The LS Chevy's actually had a TSB addressing the same thing, and one symptom was a ticking engine. I'll see if I can find it in my archives.

And you wouldn't need that much aeration of the oil for those tiny bubbles to implode inside the bearing if the bearing conditions were right for cavitation. Keep in mind how much oil whipping etc is going on inside an engine ... lots of chance for some aeration to some degree.

 

[GT Pony]

And who knows, even if some of that vapor is air, Ceratec may in fact affect the oils ability to release imparted air molecules as well. We know solids added to liquids do affect their ability to boil and vaporize. No reason to believe it wouldn't affect small amounts of air molecules in the oil as well.

There is no proof whatsoever, so chalk that up to just another "theory".

If Ceratec was so effective at preventing cavitation, then why do some guys Coyote still tick with Ceratec installed .. even with 2 bottles installed, let alone only 150 ml in 10 qts like you use.

 

[GT Pony]

Here's that Corvette TSB about the bad oil pick-up O-ring causing oil aeration and resulting in engine ticking noises (cavitation ?). See attached PDF.

 

[Condor1970]

There is no proof whatsoever, so chalk that up to just another "theory".

If Ceratec was so effective at preventing cavitation, then why do some guys Coyote still tick with Ceratec installed .. even with 2 bottles installed, let alone only 150 ml in 10 qts like you use.

And yes, that would be a theory as far as air is concerned. However, basic knowledge of chemistry does easily make sense that it affects the oils vaporization point under rapid pressure changes.

Ceratec, like any additive, only affects the oil to a certain point. It's obviously not a miracle. I have noticed that as I add it, the ticking gets slowly better and better, until I add enough to make it basically go away in all circumstances. That doesn't mean it will work for every occasion, since it obviously only affects the oil to a certain point, and every engine is physically different, with different oil being used as well.

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