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 | TomG
Join Date: Feb 2002 Posts: 5406 Upper Ottawa Valley 
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2000-11-26 21826
I never thought much about anti-freeze. My dealer asked when it was changed when the tractor was there. He said it should be changed every two years and a diesel rated anti-freeze should be used. I had it changed and didn't think much more about it. However, I heard the same thing again today. A guy on another board, whose opinions I respect, was saying that 'auto store' anti-freezes should be avoided unless they are specified as 'low-silicate' or 'heavy diesel engine rated.' I wonder what's the deal on diesel ratings in general and low-silicate ratings specifically. I also wonder how important these recommendations are.
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| Roger L.
Join Date: Jun 1999 Posts: 0 
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2000-11-26 21831
Tom, I suspect you are going to get a lot of mail on this! Some diesel engines are known to have problems with cylinder wall pitting and it has plagued diesels for many years. There are lots of theories as to why this is so. One of the favorites is that on some engines one of the frequency multiples of the common "diesel knock" is resonant with the lower portion of the cylinder. The high freqency ringing that this causes in this part of the cylinder causes local cavitation bubbles to form on imperfections where the coolant passes over the cylinder wall. As these bubbles form and collapse you have cavitation erosion of the cylinder wall. I've seen pictures of damaged cylinder walls and it certainly looks like cavitation erosion. Looks like...walks like....quacks like....who knows?
Its a pretty theory. There are others just as good.
Design remedies would be to thicken the afflicted part so as to raise the resonant frequency so high that the available energy is not sufficient to cause damage, change the material (cast iron is better than steel), or to add damping to the system. Some diesels spray oil on the inside of the lower cylinder which was originally thought help by adding lubrication there, but might be that it just added damping to the entire vibrating system.
There are also some cooling system additives available that change the surface tension of the coolant and reduce its ability to form the damaging bubbles. This is probably what your friend refers to when saying that 'heavy diesel engine rating' antifreeze is required. Some diesels need this and others do not seem to have the problem. I do not know of any downside to using these additives, but I haven't looked into them for my own tractors since they are not a type that develops the problem. My wife does use the coolant additive in her Ford diesel pickup since the Navistar engine series is one design where this cavitation erosion is well documented and the additive is said to help. The additive must have a limited life in the coolant, because renewing it is a standard Ford service procedure every so many miles/months.
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| TomG
Join Date: Feb 2002 Posts: 5406 Upper Ottawa Valley
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2000-11-27 21853
Thanks Roger. Fascinating explanation. The anti-freeze discussion actually was on the @agriculture board (the big tractor folks). I don't often comment there on tractor subjects. The sorts of problems mechanical problems dealt with there seem very different than those found on compacts.
There was more discussion today. Cavitation was mentioned, but without your explanation. I was thinking in terms of the water pump and not making much sense of the comments. The additive was mentioned, and an opinion that high-silicate coolant is best for aluminum engines. I think there also was a comment that high silicate coolant contributes to deposits in rad cores.
From my years in the sound business, your theoretical explanation makes me think of 'standing waves.' All acoustic space has resonant audio frequencies, unless the enclosure surfaces are acoustically dead. Standing waves occur at resonate frequencies and are almost self-sustaining. They build up, and even a little bit of energy at the particular frequency maintains them. Standing waves can create huge difficulties for sound systems. Fortunately most primary frequency waves are below audio frequencies except in small rooms. However, harmonic frequencies can create problems for which there are no good solutions. Anyway, I can see that if an engine has resonate frequencies, then high-energy sound waves could build up. The amplitudes of these waves certainly could have enough energy to knock coolant off water-jacket walls even when they are completely submerged.
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| Roger L.
Join Date: Jun 1999 Posts: 0
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2000-11-27 21856
Hmmm...Yes, what you are describing with sound waves is the same type of resonance, except in air and walls instead of liquid and walls. It occurs to me I should defined "cavitation" more closely. Cavitation happens when there is a sufficient difference of pressure in a liquid. Specifically, it happens when the pressure in a local area in the fluid is lower than the vapor pressure of the fluid itself. Then the fluid in that area suddenly turns to a gas - forming a bubble. The bubble collapses when the pressure returns.
You are right to think about the water pump, because one of the things that causes a rapid change of pressure (cavitation) is when a flow of water goes past a sharp obstruction. It takes a pretty good flow velocity to do that and as you point out, the water pump in your tractor is not that strong.
Or you can cause the same pressure drop by reversing the situation....by moving the obstruction rapidly within the existing fluid! That is exactly what is happening with the vibration.
Another common way of causing cavitation is adding heat - we call these "hot spots" if they happen in an engine. Of course we do this when we cook and call it "boiling". Yet another way is to reduce the overall pressure on the surface of a liquid. You can see this happen to water in a vacuum chamber. ....
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 | Art White
Join Date: Jan 2000 Posts: 6898 Waterville New York
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2000-11-27 21861
Roger did a great job of explaining cavitation. It was found at first in wet sleeve engines which makes it easier to cool the combustion area of the engine. The problem is these cylinder walls actually move while the piston is going up and down adding to the problem. The jets of oil that Roger talk's of where explained to us as for piston cooling and are mainly used in turbo engines. Some engine manufacter's are saying there non-sleeve blocks are having the same problem. To many of us it is a sand pit in the forging and a flaw in the block. Everyone is trying to do more with less and there are limits as to how far we can stetch a item before it gives out. The cavitation on a wet sleeve engine is always to the inside of the engine (cam side)which does have the most amount of heat and motion. We sometimes see what we call (western tune-ups) in are farm tractors where they actually fill the pits in the sleeve rotate them 180 degree's and reinstall them with new seals. ....
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| TomG
Join Date: Feb 2002 Posts: 5406 Upper Ottawa Valley
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2000-11-28 21886
Thanks Art & Roger. Think I've got it now. I was thinking cavitation would result from the high-pressure peaks of a standing wave. Seems like it occurs at the low-pressure amplitudes. Sort of like why scuba divers use pressure chambers and astronauts wear pressure suits. If the standing wave is fairly high frequency, then vapour bubbles could form and disappear many times a second. Guess I can now see how that could erode metal. Of course, casting or forging flaws would be candidates for pitting as well. I suppose sleeves, and pistons for that matter, all could be sand-cast, die cast or forged. Current reality seems to be that, irrespective of which process was the most durable or maintenance free, the least expensive process is going to be used. Too bad things seem to work like that.
Again, thanks for indulging my theoretical curiosity. Now, for the practical, I wonder whether the coolant additive (Nacool is a brand, I think) is worth using in a small diesel engine.
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| Roger L.
Join Date: Jun 1999 Posts: 0
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2000-11-28 21889
Art, I'll have to add that description of a "Western tune up" to my list of mechanical chuckles. I have no doubt that it would work - more or less - and have to wonder for how long. Ingenious solution. If they fill in the pits with some sort of welding or metal process, then the surface anneal would help to reduce the work hardening of the the entire liner and this is a plus for some alloys when they are faced with vibration. All in all this pitting is a problem that the designers will eventually figure out and fix. You are right in that small pits or inclusions - even microscopic ones - are "precursors" to bigger craters and cracks. That is why some high stress parts have polished surfaces.
Tom, I disagree that things are always made cheaper. I know it seems that way sometimes, but better to think of it as not spending money unless the gains that you get - in reliability or whatever - for that money are proveable. Its not an all bad philosophy; there is still development money to improve a product, it just has to be better justified so that the company will stay in business. It probably slows progress on individual products, but improves progress for the industry as a whole.
As far as the efficiency of the coolant additives, I'll have to bow to someone with experience here. Could be that Art knows. I just don't have any knowledge based on experience. I can't think of any downsides...but that doesn't mean that there aren't any. Is it necessary? The answer is a solid "maybe"! :-) If it helps you decide, I'm thinking that if someone comes up with one that sounds good from a science viewpoint I'll probably try it in my own compact. ....
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| Art White
Join Date: Jan 2000 Posts: 6898 Waterville New York
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2000-11-28 21896
Roger I don't know how long they last either we just get to see them after they have finally failed with no more clean sides. If you look at the new block design that Cummins uses on the 505cu-in engine you will notice they use three supports for the sleeve one top middle and bottom with the middle actually being the coolant stop. The treatment we use in our engines protects against corrosion,scale,foam and cylinder sleeve pitting. These features of this product are listed on the bottle and it is provided to us from Case-IH. It's always worked for me. ....
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| ThatGuy
Join Date: Nov 2010 Posts: 23 florida
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2000-11-28 21897
You can purchase test strips that you can dip in the anti-freeze and it gives you both the level of protection of the anti-freeze and if the level of the additive (nalcool or equilivant) is sufficiant to prevent damage. You just match the color the strip turns to the color chart on the bottle. If the additive level is not sufficiant it will also tell you how much additive to add to the anti-freeze. Any large truck dealerships/shop and truck parts counters (NAPA should carry them also, but autozone etc may not) will have these strips or can order them for you. If memory serves me correctly they are not cheap, but much less expensive than destroying an engine. ....
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| TomG
Join Date: Feb 2002 Posts: 5406 Upper Ottawa Valley
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2000-11-29 21915
Thanks again. A product was mentioned on the other board (blue in colour) that is pre-mixed with water and Nalcool additive. Another comment indicated that the additive life is more like months rather than a standard two-year change interval. Good suggestion about the testing strips.
The discussion has cleared up a mystery for me. When my dealer service manager asked me when I changed the coolant, he commented that they had a log skider in. He said that the coolant was never changed and that the skider was destroyed. Now I can guess what actually was destroyed.
Regarding my negative comments about design and quality. I'm less cranky if I stay out of mass merchandizing box stores, but this isn't the time of year that's easy to stay out of them. I've seen too many zero design products that are dumped onto the consumer market and just don't work. I've got a junk pile that includes almost new hand pumps, air tools etc, and even a chain saw that never cut one thing. However, I know that everything isn't like that and it's a good idea to take a longer-term view. I did know somebody who hired into one of the 'big three’ in the early-70's as a junior engineer. He quit in little more than a year. His stated reason was that little seemed to matter except production costs in designs that were approved. Evaluation criteria like expected service life, maintenance costs etc. were virtually insignificant. Of course, the '70's was not a great era for Detroit, but they did pass
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| Rich Allen
Join Date: Posts: 1
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2000-11-29 21917
Let me float a question: after I purchased a Kub. l3000dt, I added some water pump lub and conditioner to the radiator. This is the same stuff that I have been using in my cars for years. I called the Kub. dealer yesterday for his opinion and he felt this was not a problem. Was I over anal and did I do more harm than good? ....
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| Roger L.
Join Date: Jun 1999 Posts: 0
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2000-11-29 21919
Tom, what did these Coolant Gurus say about negatives for the additive? I've yet to see anything (other than my first love) that had no flaws at all. Most seem to agree that the additive "wears out", I've heard this myself. So my question is why does it wear out? What happens to it? It sure is odd for fluid properties like surface tension and viscosity to "wear out". Maybe something in the fluid interacts with something in the engine....but what is the process? And what is the end result? What happens to the magic when it "wears out"?
I'm keeping in mind that your original question was about coolants and that it was me who complicated it by bringing up the whole vibration pitting theory. That is only one of several theories, although it is popular now because it seems to explain a lot. But it could be entirely wrong,in which case the coolant additives are a red (or green!)herring. Remember: additive or not, pitting doesn't always happen.
About the mass-producted products, I mostly avoid them. There always seems to be some small company who makes a similar item with quality as the first criteria - finding those outfits is part of the fun for me. Regarding chainsaws, I bought mine in 1970 from an almost unknown (at the time) company called Stihl. I believe it cost at least three times the price of a domestic one. It works as good today as when I got it. Maybe I got lucky that time. I don't mind paying more, but I want to know in great detail what I am paying for. ....
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| Art White
Join Date: Jan 2000 Posts: 6898 Waterville New York
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2000-11-29 21932
I'll go one step further in trying to help as to what cavatation is or how it gets started. Once again I will say that it does only happen in a wet sleeve engine. A normal block without sleeves or even with drt sleeves should not have the cavatation problem. On a wet sleeved engine the sleeves are so thin that the wall of the cylinders actually move when the piston is going up and down. This is with worn out antifreeze, hard water added to the system you get cavatation. With out proper protection in wet sleeve engines I've seen it take less that 500 hours of operation for it to happen. To say it would happen in a non wet sleeve block, no. I would say that would be a sand hole or imperfection in the block. If the block was built so thin as to have wall movement with the piston working I would have to say it would not even be a boreable block which most every manufacturer will give you .030 mininmum to bore. ....
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| Ken Califf
Join Date: Posts: 1
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2000-11-29 21945
After hearing about this liner pitting problem from the John Deere rep at our local tractor expo last month, I took his recommendation and bought their "Cool-Gard" antifreeze that protects against pitting. The part number is TY16034 for 1 gallon size containers and was approximately $9.00 per gallon. Beats rebuilding a bad engine. I had Prestone in the engine for about 20 hours, but I hope it hasn't had any damage. ....
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| Roger L.
Join Date: Jun 1999 Posts: 0
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2000-11-29 21947
Art, I'm glad to hear you say that from your experience. It is the same story that I am hearing - although I don't turn wrenches any longer I do keep in touch. What you are reporting also fits exactly what one would expect to happen with the cavitation theory.
We ought to mention that although it does seem to be related to wet sleeved motors, not all wet sleeved engines have the problem. In fact most do not. And to spare Ken some worry, the problem is one of cumulative damage. It doesn't happen all at once. All motors have surface imperfections. This is good, because you want a certain amount of pits and scratches to hold the oil when the engine is not running. The way to think about it is that you do not want existing pits to grow larger. That is the main thing. I think Art will agree that it is a slow process - right until the end - and rare on low hour motors.
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| TomG
Join Date: Feb 2002 Posts: 5406 Upper Ottawa Valley
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2000-11-30 21967
Roger: There was nothing said in the other discussion about negatives or reasons for short additive life. The discussion here is starting to get into physics. I believe there is more expertise here anyway, at least in for theory subjects.
I started into something long-winded about theory. It might be interesting, but wouldn't contribute anything directly. So, I'll keep it short and observe that I do enjoy the discussions here, which can be very good mixtures of theory and experience. Guess I will make a theory note. In live sound engineering, the word 'imponderables' is used a lot. Audio performance in a room is very complex, unstable, and not entirely understood. I can remember re-equalizing the same system for the same band in the same room each day of a performance to control feedback. A lot of what makes good or bad sound is the engineer's grasp of both the theory and the imponderables. From that perspective, it doesn't surprise me that some engines pit and others don't, or some may pit from cavitation and others from casting flaws. In terms of coolant additives, I'll sort of think of them like audio compressors. A compressor almost always is used for a singer's mic channel. If the singer is skilled, the compressor isn't needed, but you won't know its there. If a singer can't control their own dynamics, a compressor is needed or an audience will blame the sound guy rather than the singer. A cranky audience could be worse than needing a new engine due to pitting.
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