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Best way to keep cool SCA OAT HOAT

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dnaraG_1M
Join Date: Aug 2010
Posts: 17 central texas
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2010-08-29          173529

Since finding this resource last week, I have been
continuing my education by reading past postings
on all jinma subjects. The subject of cavitation
really caught my eye since I was unaware of the problem.
Like a dummy, I have had the wrong coolant in my tractor.

Learning about SCAs to fight cavitation, I did some web
research elsewhere and began to understand the need to
maintain the surface coating on the sleeves. But, also
found references to newer - non nitrite - way of doing
the same thing, using OAT and HOAT coolants. Some folks
state that these technologies are "better" than SCA.

They point to the fact that you no longer need to use test
strips, SCA additives, etc, but simply do one addition of
"additives" at the 3 year mark of a 6 year life. It is also
claimed that the fatty acids that replace nitrite are more
beneficial to your water pump, providing lube that SCA
doesn't.

Sounds good. But - there's always a "but", isn't there -
the discussions elsewhere were always about big old auto
and truck diesel engines, not little tractors. So my
question is: Is this info valid for my Jinma?

I'm not gonna fire my tractor up again until I have flushed
the system and put in the *RIGHT* coolant. But I don't
want to proceed until I'm sure I've got the best coolant
possible. Last week it was 107 here in Austin - thought I
was back in Phoenix (AridZoneA) again!!!

Thanks to all,
johnd


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earthwrks
Join Date: Dec 2003
Posts: 3853 Home Office in Flat Rock, Michigan
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2010-08-29          173530

According to my automotive engineer friend and circle track car owner, it's virtually impossible to get rid of cavitation. It is inherent as it's a result of combustion energy vibrating the water molecules, which then act like scrubbing bubbles erroding the liners. All but my my dump truck and man lift are gassers. What do I do about it? Nuthing.

And again according to my friend even gas engines have it. ....

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richwaugh
Join Date: Mar 2010
Posts: 96
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2010-08-29          173532

With a diesel engine you absolutely DO wantto use a coolant with some form of supplemental cooling additives (SCA's) - nitrite SCA's are the standard now, but I would not be surprised to hear that there are newer compounds on the horizon that may be better. Since I know that the SCA coolants work, that's what I use. I do add a water pump lubricant additive to my coolant, though.

Whatever you ultimately decide on, you're dong the right thing to flush the system and change to the proper type of coolant.

Rich ....

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dnaraG_1M
Join Date: Aug 2010
Posts: 17 central texas
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2010-08-29          173533

Hmmmm.

Not having experience as a ME, I tread on thin ice
with regard to mechanical issues, so have to go easy. But,
the white papers that I found are at somewhat variance to
that. Not direct opposition, but different.

What I found focuses on the issue of Wet Sleeve as the
primary issue. They don't deny the fact of cavitation
in Dry Sleeve engines, but point out a problem of Degree,
not Kind. IE the thinner metal of wet sleeve will vibrate
more than the thicker metal of Dry Sleeve plus casting wall
for the same energy input. That does make sense to me as
thicker metal should be "stiffer" and have a lower
resonant frequency. Yes?

They also mention the issue of thinner metal being
penetrated more easily. IE With Dry Sleeve, cavitation
can remove some metal without ever reaching the sleeve.
Thus it can occur for a longer period of time without
fatal damage.....That sounds right too...?

As far a gas engines go, none of the papers that I read
address the issue directly. But, indirectly, they imply
that the diesel higher compression and greater combustion
pressures exert more force on the cylinder walls than
gas engines. I've no clue as to the reasonableness of that.

Still learning,
johnd
....

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hardwood
Join Date: Dec 2002
Posts: 3583 iowa
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2010-08-29          173534

Some expensive experience that I can share here.
I at one time owned three case 70 and 90 series farm tractors all equiped with their 504 CID turbocharged diesels. They were quite famous for their cavatation issues, and I probably could still come up with the repair bills to document it. The Case company's soulution was to add a bypass type coolant filter into the system that had a chemical "pill" that would rattle around in a new filter, then gradually dissolve adding something to the coolant to prevent the cavatation. This did solve the problem for me, I don't know who owns those tractors now, but hopefully this didn't happen again for them.
According to son No. 1 who has worked for a major oil co. for a long time, their research on whatever the "Safe" to the environment coolants they came up with to replace Ethelene Glycol that the cat could drink wasn't so great either. The contaminats the new stuff picked up from inside the engine when drained to replace it ended up making the new stuff just a higher priced product for the consumer that in the end did very little to save the planet. Well maybe the cat could drink it a little longer before it did him in.
Frank. ....

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greg_g
Join Date: Jan 2004
Posts: 1816 Western Kentucky
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2010-08-29          173537

I think the "but" here John, is not the validity of your research - but the availability of the products promoted. Clearly the near term answer is just to buy what's currently available locally.

Technically, SCAs are recommended for wet-sleeved diesels. Dry sleeved diesels are said to be ok with coolants as used in gasoline engines. If you know your engine is wet-sleeved (or if your not sure), use SCAs - or the newer stuff you read about. If you know your engine is dry-sleeved, using SCA-type or conventional is a matter of owner discretion.

//greg// ....

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dnaraG_1M
Join Date: Aug 2010
Posts: 17 central texas
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2010-08-29          173539

>I think the "but" here John, is not the validity of your
>research - but the availability of the products promoted.
>Clearly the near term answer is just to buy what's
>currently available locally.
Yeah that seems right. I don't know how "new" the
OAT & HOAT coolants are. I'll spend some time Monday
checking. NAPA website lists several; maybe the local
store in austin may stock some. Or the Tractor Supply
down the road.

>Technically, SCAs are recommended for wet-sleeved diesels.
> Dry sleeved diesels are said to be ok with coolants as
>used in gasoline engines.
That seems to be the general agreement, with only an
exception or two. So I'll go with the majority.

>If you know your engine is wet-sleeved (or if your not
> sure), use SCAs - or the newer stuff you read about.
>If you know your engine is dry-sleeved, using SCA-type
>or conventional is a matter of owner discretion.
One of your earlier post indicated that the jinma 3 cylinder
28 horse is, in fact, wet sleeved. Can't go wrong by being
careful, in any case. If I'm wrong and it's a dry engine,
no harm done......

After posting this AM, I drained the coolant (Ugh!) and
used a flush. The original fluid was standard auto stuff
that I put in earlier - no chinese gunk. But it looked bad
for low hours. No particles big enough to see with my
Mark 1 Eyeball, but definite rusty color to the green.

That was in contrast to the coolant in my truck that I
decided to change "while I was at it". I have been religious
with the fluids in my '95 Tacoma and it was close to time
to change coolant. In contrast to the opaque jinma fluid,
it came out totally clear - light green now - with not
a speck of rust or rust color. If it wasn't for the
lighter color, you would think that it just came out
of the jug.

To say I'm a believer is an under statement!!

Have a nice weekend,
johnd
....

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richwaugh
Join Date: Mar 2010
Posts: 96
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2010-08-29          173540

Very wise decision, John. Your engine is definitely a wet-sleeve type and it needs the SCA's to survive. Diesel engines take a greater toll on coolants and lubricants than gas engines do , so you want to use the best you can get and change them faithfully. Most of the bigger commercial/industrial diesels also use a coolant filter to remove the particulate crud in an effort to prolong coolant life and, thereby, extend engine life. Even on a little 3-cylinder Chinese engine a filter would be a good idea if you could figure out a convenient place to mount one.

Rich ....

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Murf
Join Date: Dec 1999
Posts: 7249 Toronto Area, Ontario, Canada
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2010-08-30          173561

IMHO one of the most overlooked additives, and again, IMHO, one of the most important additives in any engine, but particularly a diesel is a good quality surfactant to help prevent those bubbles in the first place.

If you can stop (or at least drastically limit) the formation of the air bubbles the damage caused by them goes down in direct proportion to that reduction.

It also increases the efficiency of the coolant, that in turn will keep cylinder wall temperatures lower, still further lowering the incidence of bubbles forming.


Best of luck. ....

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dnaraG_1M
Join Date: Aug 2010
Posts: 17 central texas
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2010-08-30          173562

Greg:
Yep finding the newer OAT / HOAT is a chase! NAPA has the
Zerex versions, but require purchase of a CASE! Three
times what I can use in my remaining lifetime...
Several web sites have it also, but shipping is about $20!

Just checked Tractor Supply's web site and they have both
the safe choice (FleetCharge) and PEAKs Global Lifetime
which the MSDS says is an OAT coolant. Guess that I'll
slip over to the store and pick up one or the other.....

Murf:
Surfactant?? Now that is an interesting idea. I have always
used a surfactant, along with cleaner, to clean up my
brass, but never considered it for a coolant. As I
understand it the bubbles are formed when the vibration
causes the sleeve to "pull away" from the coolant. Would
lowered surface tension (surfactant) cause the coolant
to follow the movement of the sleeve? I had the idea that
the inertia (mass) of the coolant prevented it from moving
fast enough to "follow" the movement of the sleeve. Would
a surfactant change that? Are there surfactants that
don't foam? (I've always used detergents)

Rich:
Never encountered a coolant filter before. Are they spin on
type? On pressure or suction side? Or maybe they operate
in parallel, filtering part of the fluid each pass?
If in series, I assume they must allow a very high flow
rate while still filtering out things smaller than
elephant dung...?? Tough job for a filter, maybe?

Thanks to all!
johnd ....

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Murf
Join Date: Dec 1999
Posts: 7249 Toronto Area, Ontario, Canada
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2010-08-30          173567

Quote:
Originally Posted by dnaraG_1M | view 173562
[QUOTE=dnaraG_1M;173562] Murf: Surfactant?? Now that is an interesting idea.

As I understand it the bubbles are formed when the vibration causes the sleeve to "pull away" from the coolant.

Would lowered surface tension (surfactant) cause the coolant to follow the movement of the sleeve? [/QUOTE]

John,

Vibration is only part of the problem, and a bubble is a bubble no matter how it forms.

Don't forget that only a fraction of an inch away from that coolant is a combustion chamber that sees (on for instance a 4 cyl. 4 stroke doing 1,800 rpm) 900 combustion cycles a minute (15 times per second) with temperatures of over 1,000° F. just from the friction of combustion, never mind the fuel burn itself. All this heat means that the coolant touching the cylinder walls is being exposed to temperatures way above that needed to make it boil.

The concept of the surfactant (such as "Water Wetter" by Redline Products) is to prevent those (and other) bubbles from forming by chemically treating the water to inhibit the formation of those bubbles. The idea being if the bubbles account for say, 20% of the surface area, then you could only achieve something around 80% of the expected cooling efficiency.


Best of luck.
....

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dnaraG_1M
Join Date: Aug 2010
Posts: 17 central texas
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2010-08-30          173568

Murf:
Ah, I think that we were on different tracks. You
are describing localized boiling that creates bubbles.
That had not occurred to me in the context of cavitation.
It does seem reasonable to me that a surfactant which
lowered surface tension - better wetting - would lower
the thermal resistance at the coolant / metal interface.
If lowered enough, perhaps the heat would flow into
the coolant mass fast enough to prevent a localized
boiling. Intriguing concept. I wonder if my wife will
let me use a pan for an experiment..!...

I was on a different track. Having grown up around boats,
I have always thought of cavitation as a purely mechanical
effect. Don't think that those props get all that hot.
It had been my understanding that the damage occurred
when the bubbles were smashed, dislodging tiny bits of
the metal prop, sleeve, or whatever..... Can you
describe what part of the thermal effect causes the damage?
Is it still the smashing of the bubbles or something
else entirely?

Which would be the predominating effect - thermal or
mechanical?

So much to learn, so little time!
johnd
....

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