I learned a nugget from my radiator man this morning I thought I might pass on. My old radiator core from my '84 Eagle 10 had a 5 row-3/4" tube setup. The new radiator core has 8 row-1/2" tube setup.
BTW, I should be back on the road tomorrow(in Denver now) and I'll let the board know how the new radiator does...
Happy Trails,
Brent
Please do Brent. I am agonizing over my temperature problems with my 10. I've been trying different things for 3 years now to try to squeeze more cooling out of what I have. So far no success. I too have a 5 row radiator.
Note the ambient temps, location, gear you are in, etc when you record some measurements. My problems tend to start around 3000 ft msl at temps above 95, moderate climbing at any speed above 60mph or 10psi or higher on the turbo gauge.
Keep us informed.
David
Brent ,
Assuming similar tube configuration and cross section, it would appear that the 8 row has about 6% more cross section and 6% more surface area than the 5 row.
On the other hand, the 1/2" tubing may have more internal resistance gobbling up the apparent "advantage". This can best be determined with a manometer set up.
It's possible that you'll experience similar (equal) cooling capacity to a properly maintained radiator like that removed. (Which is not my point)
With a new core (assuming everything else is also up to snuff) continued overheating or marginal heating is an indication that you're aerating the coolant somehow, which is my point to Dave Anderson.
Dave,
What set up do you have in your Eagle 10?
Is your system cleaned out, etc.? Have you upped the horsepower? Anything else (plumbed the genset into radiator system?) ?
How would you be able to tell if the coolant is getting aerated?
Just my humble observation between my old core and the new one:
1) The new ubes seem to be staggered vs the old core that looked like an Olde English Military regiment
2) The fins on the new tubes seem to be louvered vs the old one that were flat
Not sure if any of that helps but I thought I would point it out.
Happy Trails,
Brent
Dave,
What set up do you have in your Eagle 10?
Is your system cleaned out, etc.? Have you upped the horsepower? Anything else (plumbed the genset into radiator system?) ?
Yes, it's cleaned. The truck radiator shop that cleaned and rodded said it looked like new, no compromise of the tubing or fins.
No, engine is an anemic 315hp
No genny, however it has the stock DD water to oil cooler and a water to oil cooler for the Voith transmission. I may begin to suspect the tranny heat could be a problem cause in climbs. I never thought of that before, but it definitely generates heat to the coolant.
David
Brian,
I guess you could install a glass/plastic tube for a visual verification.
But that will only work easy on a dyno, since the test has to be under power and at regular temp.
The easiest way I know to check is run a manometer check on the system to check pressure drop through the the heat rejection portion.
This is technical and every time I try to explain these points I catch flack, so "flack it" I'll just have to show ya! LOL!!!
I'm checking into building the apparatus now to perform this test. If I make it to Busn'2007 with RJ Long at Arcadia this New Year's I'll bring it with me and see if I can find a willing overheat victim.
Marc
Checked on the question.
Radiator mfgs test cooling system resistance with air, not coolant (believe it or not, air is more accurate)
Field test using manometer set-ups are fine. The accuracy of air tests isn't necessary to determine whether coolant will aerate.
I'm getting a drawing sent of the proven set-up and will make one with a couple of adaptors for various installations.
Marc Bourget
The only Eagle radiator trivia I have is the phone number to the company that built the radiators for Eagle. Atlas Radiator (Larry) 361-882-5661. Corpus Christi, TX..................................Great guy.......................
Rich
800-468-5287
Dave,
8V71, 740 Allison, 15KW Kubota Wrico genny plumbed into bus radiator. I had a couple of days running the generator before it went out and noted that the temp gauge did not climb over 180 from Denver thru Kansas to Missouri...there are some small climbs out there that would have sent my previous setup into the overheat zone. Most of the time the temp gauge is below 180...175 or lower. It was expensive by the time I bought new top/bottom tanks and side rails, plus the core, plus S&S putting it in. I'm also running the Detroit pink 50/50 mix coolant.
Guys, what is too cool while running down the road? 170 ok?
Happy Trails,
Brent
Brent,
That is good to hear. I'm taking my radiator to a shop Monday to upgrade to the best cooling technology available. I'll keep you guys posted on the proposal they give me.
David
I got my results from the radiator shop in San Antonio. My core is a 5 row 3/4" tube 32x37.5x4.5" fin area with a rated 10,000btu rejection.
They can build me a new core with 1/2" tubes 6" thick for a 11,200 btu heat rejection rating all for the nominal price of $2470. LOL. Darn, copper has gone up.
I'm not sure if I want to do it this way. I'm trying to get in touch with Tom at Dever Radiator to see what his take on it is. I think he would have a better understanding since he builds this stuff to run in high mountain altitudes Also, I emailed Voith USA to determine what the heat rejection is on my tranny. It should be similar to an Allison, but I'd like to know.
So, far, Richard's suggestion of the Hayden fans (see the thread about "auxiliary fans") is the cheapest idea.
David
I just got off the phone with Tom at Denver Radiator and they can build a 7 row dimpled tube 12000 btu heat rejection core for me for about $1700. I wonder if a 20% gain in efficiency is enough??
David
David,
I wonder why my radiator was so much more from Denver Radiator? Is yours a different spec or size?
-Brent
I'm not sure. I will reuse my tanks and rails, only replacing the core. However, I may defer on this core replacement. I had a long conversation with Gene Rochester today. (Most of the older board followers will remember him). Anyway, when he repowered his eagle with a 500hp 8v92, he had severe heating problems. He finally switched to a big honking fan out of a GMC. He remembered the blades were twice the size of the OEM eagle fan. He also enlarged the drive pulley to spin it faster. It moved so much air it would suck your body up to it when you walked by.
I later had a conversation with the owner of Texas Custom Coach. He found a European 16 blade variable pitch composite fan that he has installed on 3 Eagles with 8-92's and solved each one's cooling problem. Ironically, he was just ready to install one on his own bus. This fan is about $450. and can be obtained from Goodson Bus Sales. I called Goodson today and will try to spec one out next Monday. This will be much cheaper than a recored radiator and perhaps a bit better than the electric aux fans that we discussed on another thread.
About this fan--I did talk to one guy at Bussin USA in 2005 that had it on his Eagle and was very pleased with the outcome. I didn't see it, but it was discussed. It seems counterintuitive that Gene's fan had less blades and more surface area, and the variable pitch fan has 16 blades. I don't have an explanation for that.
The fan issue and air volume was strongly emphasized by the head engineer at Atlas Radiator in Corpus Christi TX. He noted that air volume was critical in these eagles with the 6 & 8 V92's with turbines. It was always a problem, thus I'm leaning more that direction as a fix over fiddling with what the radiator shop told me is a fundamentally adequate radiator.
David
David, I did a little math on the numbers that you furnished. The 12000 btu number was per minute, I figured, which meant that the btu/hr comes to 720,000.
Using your horsepower figure of 315 and allowing 1 gph per 15 hp for a good condition 2 stroke, I got a maximum fuel consumption of 21 gph. That much fuel per hour has nearly 3 million btu. On the older diesels, about 1/3 of the energy from the fuel will wind up in the cooling system; in this case, that would be 1 million btu at the maximum power of the engine.
Any additional heat from charge air or transmission will only raise that number. A 6V92TA with a V730 might go as much as 50% higher.
I didn't see where you mentioned what temperature difference between the coolant and the cooling air would give you the 12,000 btu/min, but it does seem to me that if you tried mountain climbing on a hot summer day, it might be pretty easy to hit the limit of your cooling.
For what it's worth.
Tom Caffrey
Suncatcher
Ketchikan, Alaska
Tom,
That is too much fuel. I get about 6.5mpg. At 70mph or 70/6.5= 10~11 gallons per hour. The 6v92 is rated for 10k btu/min heat rejection. That is what I was told my radiator was rated. I'm a little short when it comes to mountain climbs and the tranny is in 1st gear dumping extra heat into the radiator.
David
David, it seems to me that you're saying your average fuel consumption is about 1/2 of the maximum that I calculated. It seems to me that you are getting what my numbers seem to show. Most of the time, there would be no overheating.
The only time that I would think that you would see overheating is when conditions were bad. Our coach doesn't run the fan at full power unless the coolant is hot enough. Because of the horsepower that the fan uses, it pays to keep the radiator in good enough shape that the fan runs as little as possible.
In the end, you are the only one that can decide how much cooling that you will need. I did the calculations to show how you could arrive at a solution to your question of whether the radiator would have enough capacity for your use.
Good luck with your cooling.
Tom Caffrey
Suncatcher
Ketchikan, Alaska
Thanks Tom,
I picked up my 16 blade fan yesterday. It fits right on the hub. The fan is huge!! I've been engineering a new shroud for this made from 14 gauge steel. I got most of it fabricated today and this will beat the heck out of that puny fiberglass shroud. I'm really encouraged about doing this because Texas Custom Coach installed this fan on 3 different Eagles with 8v92's and it totally solved their problem. Gene Rochester installed a larger fan on his 500hp eagle and kicked his problem, too. I'm not making mine spin faster with this installation. I wanted to try it stock, first.
So, there you have it. I had the chief engineer from Atlas Radiator (who made them for Eagle) tell me to move more air.
I have Gene telling me to move more air.
TX Custom Coach moved more air.
By golly, I'm gonna move more air across my radiator. Hopefully I'll have this done by Monday for a test run. It is still 103 here and I'd like to get the coach out while it is still blistering hot.
David
1. What did you use for a build reference when making your shroud?
2. What radii did you use for the shroud transitions?
3. How far will the fan "insert" into the shroud?
4. Do the fan tips match the radius of curvature of the exit shroud?
5. Do you plan on checking pressure drop within the shroud against ambient with a manometer BEFORE YOU GET TO PEAK RPM?
6. You say the fan was huge but will be spun at the same RPM. Did you perform a tip speed calculation (Pi x diameter x (max) RPM= ??)
7. Are you sure you want to test to peak RPM before performing #s 5 and 6?
8. If your answer to 7 is yes, I'd advise you make sure nothing (person or property) important is both close and in the plane of the fan's rotation!
Good Luck!
Onward and Upward
Marc Bourget
Quote from: Burgermeister on August 24, 2006, 12:06:35 AM
1. What did you use for a build reference when making your shroud?
The fan diameter
2. What radii did you use for the shroud transitions?
Not sure what you mean.
3. How far will the fan "insert" into the shroud?
The blade edge is even with the radiator side of the shroud and about 3/4" of the edge is outside the shroud (towards the engine)
4. Do the fan tips match the radius of curvature of the exit shroud?
Not sure what you mean
5. Do you plan on checking pressure drop within the shroud against ambient with a manometer BEFORE YOU GET TO PEAK RPM?
No
6. You say the fan was huge but will be spun at the same RPM. Did you perform a tip speed calculation (Pi x diameter x (max) RPM= ??)
No
7. Are you sure you want to test to peak RPM before performing #s 5 and 6?
Yes
8. If your answer to 7 is yes, I'd advise you make sure nothing (person or property) important is both close and in the plane of the fan's rotation!
Ok.
I finally got all this together and took it out for a test run. The ambient temperature was 100. I pushed the coach to 75 and maxed out the turbo boost as best I could. The gauge never went above 184. My t-stats are full open at 185. The most impressive result is my delta. I made a quick stop on the roadside when I got it as hot as I could. My inlet temp in the radiator was 184 and my outlet temp on the suction pipe to the water pump was 150. Never, ever have I achieved better than a delta of 10.
When I put the coach at high idle I almost get sucked in when I walk by the radiator. The fan sounds similar to a jet turbine. This fan was pitched for an Eagle by the manufacturer, so I assume all the engineering is good.
As far as the shroud construction, I just boxed in the entire radiator hole in the bus. the whole radiator is sealed into the hole. This eliminated any need for compound curves on the shroud. It is flat steel with a hole in it and a 1" ring for strength. The whole thing is pretty stout as I wanted NO wiggle or flutter anywhere in the shroud.
I have a 1200 mile trip on the 16th. That will be a good test.
David
David
Awesome David! Good job putting it together.
Question: Did you use some sort of thermostatically or manually controlled clutch on the fan so you aren't consuming power when you don't need maximum cooling (like in the winter)?
No,
That is more money. Maybe next year. I figured when I'm going 75 on the flat it won't make much difference with the fan running full speed anyway. When I'm climbing that long hill, the engine will require all the fan I can muster to relieve the heat. My fan is direct belt and pulley drive off the miter box, and I use 180 t-stats, so I have no trouble keeping the temp up even in cold weather.
The fan cost me $472 from Goodson Bus Sales 828-428-4102. The parts for the shroud were about $112 bought from my local metal supplier. It took me about 12 hours to get it all together. I did have the welder cut the hole with a plasma cutter. He did a perfect job. That was included in the $112.
David
We just finished a 1300 mile trip up IH 35 to Kansas and back. The engine never bumped above 185 on the engine room gauge (full open t-stat is 185). It was only 95 degrees ambient and just a few rolling hills through central Texas, but I'm impressed with the results. I do have a sense that the engine room may get too cool in the winter. However, I never saw the cockpit gauge fall below 170 while driving. I may be throwing blankets over the intake next winter.
Where and what would I look for in a thermostatically controlled fan clutch, and how much would such a beast cost?
David
Dave,
Excuse me, but what engine do you have in your bus?
Stock cooling configuration, including sizes of hoses and fittings.
Do you have access to a magnahelic or manometer to check the "Delta P" between the core and shroud and before the fan?
It would be ironic if you have adequate radiator and fan whose efforts are being defeated by an aeration problem.
Excuse me, but what engine do you have in your bus?
6v92 set at an anemic 315 hp with the throttle delay to minimize smoke.
Stock cooling configuration, including sizes of hoses and fittings.
5 row radiator OEM for a 1985 model 10, 41" wide. I believe the fittings are 2".
Do you have access to a magnahelic or manometer to check the "Delta P" between the core and shroud and before the fan?
No I don't, but I wonder if I could accurately measure the core front and back (through the fan blades) with my temp gun?? Never tried it that way.
It would be ironic if you have adequate radiator and fan whose efforts are being defeated by an aeration problem.
I was told by two engineers that the radiator was adequate, thus my valiant search for a better fan. Thanks to Dave at Texas Custom Coach in Pipe Creek TX, I feel like I've found the right fan. He suggested it and steered me to Goodson Bus Sales to buy it.
David
David,
The adequacy of the radiator is irrelevant if the coolant is experiencing aeration. But if it's a stock system and no internal corrosion, I'd suspect that it's alright.
I'm trying to make Arcadia with a special type of manometer setup to check Cooking System Delta P (Pressure) If you're around then, and wish to serve as a "guinea pig", the test will give a good indication if the system is aerating the coolant.
Marc Bourget
How does the fan air pressure affect the aeration of the engine coolant? ???
If you check the air flow with a manometer, How can that tell you if your coolant is aerating?
Just curious!
When I built my cooling system I used a piece of clear hose, then used my backup camera to check out the flow while driving.
FWIW,
Dale
Hey that's good news Marc! It'll be nice to finally see your bus and work in progress! I know it's beena long long hard road getting it to where you can use it but I'm sure it will be worth the trip for you and everyone else that finally will have the opportunity to see all that knowledge put to good use! ;)
Ace!
;D ;D ;D
Happycampersrus posted:
How does the fan air pressure affect the aeration of the engine coolant? It doesn't - two separate things.
If you check the air flow with a manometer, How can that tell you if your coolant is aerating?
I'm talking about checking aeration within the coolant, as it circulates with a special type of manometer setup.
So as not to confuse by the above, I have spoke in the past about checking pressure differential "drop", between the radiator core and the fan, within the shroud, using a different (i.e., traditional) manometer setup.
Reply to Ace,
If I make it, I'm coming, once again, by airliner, with RJ Long and hopefully Bob Sheaves.
The desire is to give the improved presentation of "All you never wanted to know about cooling systems and were afraid to ask! Seminar, originally given in Rickreal at Bus'sUSA 2006.
The manometer setup is a testing device inserted in the "stream" of coolant and used to see if conditions favorable to the propagation of coolant aeration exist.
There's too many variable factors to allow someone to "look" at my bus and figure what "their" bus needs or doesn't need.
I ain't retired and, frankly, don't want to take enough time off to drive a bus to Arcadia just for Bus'n 2007.
The stuff I talk about is simply the proper application of proven technology. Some of it borrowed from other disciplines. If I can't explain my points adequately, there's no reason the presence of my bus will make a difference. Any set-up can be "tricked" witness the various mileage claims or fuel from water scams - etc..
With taking anything away from you or other builders - rightly proud of your collective work, I'll complete my bus, my way, in my own time. It's for me - not for seeking "Look what I can do" attention.
It'll be awhile, should I live long enough, before my bus gets completed and to the East Coast.
Marc Bourget
The following link is a good writeup on coolants and problems experienced with different situations which may be of interest. Especially with those that have engines with sleeves.
The article discusses aeration very briefly with the following statement:
"Maintaining electrical grounds is an essential aspect of cooling-system maintenance, because stray electrical currents can cause problems in cooling systems. Regularly check ground connections for the batteries and starter, and be careful to properly ground any add-on accessories.
On the other hand, aeration in a cooling system can cause problems that are sometimes blamed on stray currents. Periodically inspect the cooling system for air leaks from loose clamps, bad hoses and bad pressure cap."[/b]
At least to these writers aeration is not a common problem and it is caused by air leaking into the coolant system. This was the only reference to aeration I could find in the article.
I have to admit that in my many years of dealing with heavy equipment, very large engine generator sets and very large luxury yacht engines I had never before heard of any problem with aeration.
Here is the link:
http://www.constructionequipment.com/article/CA6256027.html
Maybe this one works:
www.constructionequipment.com/article/CA6256027.html (http://www.constructionequipment.com/article/CA6256027.html)
Sorry, neither link seems to be working at the present time so I will just paste the writeup here.
Richard
http://www.constructionequipment.com/article/CA6256027.html
Prevention Illustrated
The Basics of Diesel-Engine Coolant
Or, a few tips that may help you stay out of cooling-system trouble in a world that's working against you
September 1, 2005
By Walt Moore, Senior Editor
Elizabeth Nelson, coolant program manager at Polaris Laboratories, a fluid-analysis company in Indianapolis, Ind., tells a story that would strike fear into the heart of any fleet manager. A class-8 on-highway truck seemed in fine condition when it left the West Coast, but at the end of its 6,000-mile cross-country run, a cylinder sleeve failed and catastrophic engine failure resulted. According to Nelson, the cause of the disaster was an electrical short in the truck's starter.
"An electrical short in a vehicle takes the path of least resistance to ground," says Nelson, "and often that's through the cooling system. In this instance, the electrical current passing through the coolant so quickly depleted the nitrite additive in the antifreeze, that the sleeves no longer had protection against cavitation. When coolant analysis shows a rapid depletion of nitrite, coupled with an increase in nitrates, it's always a red flag for an electrical short."
A combustion-gas leak, on the other hand, says Nelson, causes a sharp drop in pH (usually below 7) and an increase in sulfates. Air leaking into the cooling system, however, typically results in a lowered pH, she says, (but usually not below 7.5) and a drop in nitrite level (but not as rapid as with an electrical problem).
What's in the radiator?
Although regular coolant analysis is a good way to keep tabs on the health of a vehicle's coolant system, coolant analysis is not nearly as popular as oil analysis. For many equipment owners, truth be told, what goes on in their machine's cooling system is somewhat of a mystery.
"Ask most fleet managers about their lube-maintenance programs, and they'll talk in detail," says Craig Gullett, brand marketing manager for Old World Industries, a major antifreeze manufacturer. "Ask about their coolant-maintenance programs, however, and more often than not, answers become rather uncertain."
A frequent weak link in coolant maintenance, and the probable cause of many coolant-related engine problems, says Carmen Ulabarro, coolants market development specialist for ChevronTexaco, is the lack of understanding about what coolant is being used in the vehicle — and how to maintain that specific formulation.
Virtually all heavy-duty antifreeze is roughly 95 percent ethylene glycol and 5 percent water and additives. The stuff that isn't made from ethylene glycol (only about 1 percent of all antifreeze sold) is made from propylene glycol, which is less toxic, but also more expensive. "Coolant" is created when glycol is mixed with various ratios of water. Typical ratios range from 30 to 60 percent glycol.
Heavy-duty antifreeze formulations differ from one another by virtue of the additive package blended into the ethylene glycol. Additive packages, of course, all have the same task, namely to fight rust, scale and corrosion — and in diesel engines, to protect wet cylinder sleeves from cavitation. But the additive packages among various antifreeze formulations have fundamentally different chemical fingerprints.
Until maybe 15 years ago, heavy-duty engines typically were filled with "conventional" antifreeze, identified by the American Society for Testing and Materials (ASTM) standard D-4985. This antifreeze, however, which is still in prevalent use today, can't be used in diesel engines without first treating it with a "supplemental coolant additive" (SCA) that contains nitrite for protecting wet sleeves. The required initial treatment is an approximate 3-percent concentration of SCA (one pint per four gallons of cooling-system capacity).
Today, the preferred conventional antifreeze for diesel engines is "fully formulated," identified as ASTM D-6210 or RP-329 by the Technology & Maintenance Council (TMC). This antifreeze is sold with an SCA package already blended in, typically including nitrate to protect iron and steel, tolyltriazole to protect copper and brass, borate or phosphate to buffer acids (formed as glycol breaks down), silicate to protect aluminum and nitrite (sometimes accompanied by molybdate) to form a cavitation-resistant barrier on sleeves.
These additives are depleted as the coolant works and ages, however, and must be replenished periodically with an SCA package. Especially critical is the renewal of an adequate nitrite level. But you must be careful here, because too much nitrite may cause solder corrosion, and excess accumulation of other additives causes "total dissolved solids" (TDS) to increase, possibly jeopardizing cooling efficiency and resulting in passage-clogging dropout. Cautious maintenance guidelines may suggest replacing fully formulated conventional coolant at two-year intervals to avoid TDS problems.
To simplify maintenance, the antifreeze industry developed "extended-life coolants" (ELC), which are formulations typically advertised with a service life of 600,000 miles or 12,000 hours. These formulations, originally at least, replaced the additive package used in fully formulated conventional antifreeze with "organic-acid inhibitors," designed to protect metal parts by forming a thin protective skin against destructive forces in the coolant.
These "organic-acid-technology" (or OAT) antifreezes use the base or neutralized version of organic (carbon-containing) acids, typically (but not always) the carboxylate acids of 2-ethyl hexanoic acid (2-EH) and/or sebacic acid. Most heavy-duty carboxylate formulations, however, also contain some of the additives used in fully formulated conventional antifreeze, namely nitrite and molybdate, and sometimes silicate. OAT formulations that include nitrite sometimes are called nitrited-organic-acid-technology antifreeze, or simply a NOAT.
According to some antifreeze experts, anytime you add inorganic inhibitors (like nitrite) to an organic-acid-based formulation, you have created a hybrid, or a Hybrid OAT, or a HOAT. Others say, though, that a hybrid is technically a product characterized by the use of non-carboxylate acids, such as benzoate, from benzoic acid, another organic acid.
Maintenance
To ChevronTexaco's Ulabarro's point, the start of good coolant maintenance begins with knowing which antifreeze formulation is in your machine's radiator.
Most NOAT formulations, for example, require the addition of an "extender" at 300,000 miles or 6,000 hours to replenish nitrite, which is used up at a far slower rate in an extended-life coolant than in a fully formulated conventional. Important to note here, perhaps, is that European engine manufacturers are evaluating — maybe even leaning toward — the use of carboxylate-based extended-life coolants without nitrite.
Don't buy into the philosophy, however, that extended-life coolant needs no regular maintenance. The experts recommend inspecting it at the vehicle's regular maintenance intervals to make sure it's clear (no rust), that the color is right (not mixed with another antifreeze type) and that it has sufficient freeze/boil protection, best determined by using a refractometer.
Maintenance guidelines for cooling systems with fully formulated conventional antifreeze typically include periodic testing of SCA levels and appropriate adjustment, as well as periodic draining, flushing and refilling the system to avoid, as already noted, an excess of dissolved solids.
You can test the additive concentration of fully formulated conventional coolant by supplying samples to a fluids-analysis laboratory. Or, you can do the testing yourself by using paper test strips, which are chemically sensitive and change color to indicate freeze/boil point (glycol content), nitrite (or nitrite/molybdate) levels and, in some instances, pH.
When the addition of an SCA is indicated, keep in mind that two major types of SCA are available, one with a nitrite/borate formulation, the other with a nitrite/molybdate/phosphate formulation. It's probably best not to mix them, and it's best to use a test strip designed for the specific formulation. Those in the know say to be careful about buying bargain-priced SCA formulations, which may be inferior. Look for a stated compliance with an ASTM standard on the package, likely D-5752, to ensure that you're buying a quality product.
Some users of fully formulated conventional antifreeze, however, employ a coolant filter charged with an SCA package. This filter/additive assembly is designed to release metered amounts of additives over time and, thus, to maintain optimum levels. As long as testing indicates proper additive levels, and provided that top-up is done with a 50/50 mix of the correct antifreeze and deionized water, the assumption is that fully formulated conventional coolant can last far longer than the often-prescribed interval of two years.
On the other hand, says ChevronTexaco's Ulabarro, some users of fully formulated conventional antifreeze drain and replace coolant every year, but do not test or add SCA packages between those service intervals, thinking that nothing will go wrong in that short time. But, depending on the specific formulation of the antifreeze and on top-up practices, says Ulabarro, critical additives could be depleted in as little as 1,000 hours, potentially leaving the engine virtually unprotected for a long time.
In the everyday world, of course, fully formulated conventional and organic-acid antifreezes are sometimes inadvertently mixed in cooling systems. The primary concern about a mixed system is that the distinctively different additive packages in the two formulations will be diluted to the point that neither has the power to afford adequate protection. You're best off, say the experts, to pick an antifreeze type, take all practical safeguards to avoid mixing it with other types, and conscientiously follow the maintenance strategy recommended for the chosen antifreeze.
Coolant Analysis
Given the changing chemistry of coolants and the increased demand placed on cooling systems by today's engines, Bryan Debshaw, CEO of Polaris Laboratories, believes that coolant analysis will become an increasingly important tool in preventive-maintenance programs. Coolant analysis not only determines coolant condition, he says, but also identifies other vehicle problems that can show up in the cooling system. Coolant-analysis programs typically are available in various levels (and costs), depending on the number of parameters checked.
A primary cause of wet-sleeve damage is cavitation, but other causes are prevalent: these sleeves have been attacked by 1) stray electrical current going to ground through the coolant; 2) calcium and magnesium scale that impedes heat transfer and is caused by water with minerals (the sleeve "blues" at 600F); and 3) chloride (in the water), which "decarbonizes" iron until it is like sand, says Elizabeth Nelson of Polaris Laboratories
Quick Tip
Using tap water in your vehicle's cooling system can undermine your best efforts at good maintenance if it creates rust, scale and corrosion. Premixed coolant, with 50 percent demineralized water, avoids these problems. So does deionized water. Talk to your local water-conditioner expert about a deionization unit. We found a local supplier who would install a "mixed bed" unit for around $200, then switch tanks as needed for $80 or $90. Typical tank life is 1,500 to 2,500 gallons of treated water.
If you use paper test strips to check the condition of fully formulated conventional antifreeze, make sure the strips are fresh and designed for the type of coolant being tested. Remember that freeze-point readings may be unreliable if glycol levels are above 60 percent.
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Wet-Sleeve Cavitation
In a wet-sleeve cooling system, antifreeze additives create a barrier between the engine's sleeves and the small bubbles that form in the coolant next to the sleeves, the result of pressure differentials. When the normal vibration of the sleeves causes the bubbles to implode, they do so with great violence and can create tiny cavities in the surface of unprotected sleeves. Left unchecked, this "cavitation" process (a leading cause of engine failure) can create holes in the sleeves and allow coolant to leak into the cylinder. Fully formulated conventional antifreeze uses nitrite, which coats the sleeves, to protect against cavitation. Organic-acid-technology antifreeze uses chemicals that plate sleeves with a thin protective layer, but these formulations also may contain nitrite.
Illustration adapted from Baldwin Filter graphic.
Conversion Possibilities
Manufacturers of at least three brands of organic-acid-technology antifreeze have programs for converting cooling systems from fully formulated conventional coolant to an organic-acid-type coolant, without draining and refilling the system. Reduced maintenance is cited as the primary benefit of conversion.
ChevronTexaco's Fleet Fix Conversion, Shell's Extended-Life Coolant Conversion, and Old World Industries' Final Charge Converter can be used to make the conversion, but the existing coolant must meet specific parameters before conversion can proceed. (Old World Industries' Final Charge antifreeze is a non-carboxylate organic-acid-based product that contains no nitrite.)
By contrast, Penray, a maker of antifreeze additives, promotes a "Fill-for-Life" strategy, which is aimed at converting nitrited-organic-acid-technology coolants to fully formulated conventional coolant. Penray's conversion strategy employs its Need-Release Filter, which uses corrosion-sensitive barriers for the timed release of SCA charges.
Electrical Grounds and Aeration
Maintaining electrical grounds is an essential aspect of cooling-system maintenance, because stray electrical currents can cause problems in cooling systems. Regularly check ground connections for the batteries and starter, and be careful to properly ground any add-on accessories.
On the other hand, aeration in a cooling system can cause problems that are sometimes blamed on stray currents. Periodically inspect the cooling system for air leaks from loose clamps, bad hoses and bad pressure cap.
Posts: 355 | Location: UK | Registered: 27 May 2001
Ok Marc,
I think I know what you are describing now. I was confused by your post on Sept, 29th. It refered to "cooking system delta p". I had never heard of such a thing and it took me a little time to put it together. ;) That post coupled with your post on Sept, 27th asking David if he had access to a manometer to check his fan threw me off.
Dale
Happycampersrus. Sorry I wasn't more clear!
Richard,
I apologize for not defining what I meant by aeration. It's not what it would seem to the lay person.
By Aeration I meant the generation of bubbles in the system caused by Internal Restriction in coolant flow, irrespective of external leaks allowing entry of air into the cooling system
Entry from external sources during operation probably only occur from combustion products, cracked head/bad head gasket, etc. To much pressure to work against.
Fact is, at elevated temps the partial pressure of the coolant will approach the system pressure. Restriction to flow in the system may result in a drop in pressure at various points in the system, most notably the intake to the coolant pump. The pressure differential is sufficient to drop the pressure below the Partial Pressure, introducing "Aeration" thru boiling. There are other mechanisms for adding air, with DD 2 strokes, the fact that they have "built in" air traps in the heads that contribute to the problem.
Aeration is quite common but is usually dealt with by responsible design of the cooling system. It rears it's ugly head with repowers, improper driving techniques or modifications to the system,
Onward and Upward
Marc Bourget
Guys I wasn't trying to "call anyone out"! I was merely asking for HONEST simple answers to questions that some of us, (other than myself) have always wondered about!
Later Gator... and yes, we all DO still get along!
Thanks Ace.
Dallas
BB members
Partial pressure is a % figure indicating, on a scale of 1-100% how "close" a fluid is to boiling at that temperature.
At Std temp and pressure (sea level) water is supposed to boil at 212 degs. F. (14.7 #/sq in) At the higher pressures of a closed cooling system 5 psi some busses to 21 psi in some cars, Temps close to 200 deg are say 90% partial pressure (for example 13.23# in a pot of water on the stove). The fluid won't boil until the temp goes higher or, if you have a good coolant pump and some restriction in the radiator, hoses, thermostats, whatever, the pump, at the inlet, will "suck" ( to use an improper term) the pressure down until it is lower than the example of 13.23 #/sq, the partial pressure now exceeds the boiling pressure (at sea level) and bubbles will form. (This is like water in Denver will boil at less than 212 deg. F)
[Keep in mind,the actual boiling point in a bus cooling system will be higher since it's under pressure. I just picked the sea level figure to give some numbers for example purposes.]
The problem is, because of surface tension effects (the thing that "enables" or makes bubbles) once the bubbles form, and go to the high pressure side of the pump, the higher pressure alone, isn't enough to collapse the bubbles. The higher pressure will make the bubbles slightly smaller, but they won't go away as easy as they're formed.. These "tiny bubbles" act as insulators and also, by their presence, reduce the "mass" of the coolant available to take the heat away.
Got to use special "tricks" to get the "stubborn" bubbles out of the coolant.
But this is part of the "All you wanted to know" seminar so I'll drop it at this point.
HTH
Marc Bourget
Quote from: Burgermeister on October 01, 2006, 07:19:31 PM
BB members
Recognizing Bryce's comment - that I get too technical and "lose" the attention of readers, I offer the following.
But this is part of the "All you wanted to know" seminar so I'll drop it at this point.
HTH
Marc Bourget
Marc I didn't mean to offend you, and it's not all of your posts you lose me on. But I am a simple ol' counrty boy who all the way from like 1st grade(or B4) couldn't understand alot of things "unless I was able to actually get a hands on experience" and also didn't understand why I needed all that crap as all I wanted to be was a truck driver! (LOL) Then I became interested in working on vehicles and had pretty much the same attitude, until they started computerizing cars (then I was lost! and I quickly put my tools in storage and went back to my first passion of driving trucks!) Thinking "After all they can't computerize trucks after all it's a DIESEL all it needs is fuel air & compression!" Boy was I ever wrong! LOL! So please don't take offense, I'm sure that everything you say is true and correct! But I get lost in all that long winded stuff, and quite frankly even if it ain't long if I can't actually get in there and "see/feel" what it is I'm still lost! I did stay in school long enough to graduate from High School (my mothers wish!). But after that it was schools out for me! I have the utmost respect for anyone who betters themselves by continuing or returning to school, it's just not for me! And to those of you who did continue and get degrees and such, congratulations and THANKS after all it's those of you who help idiots like me survive even if we don't understand most of what ya say! BK ;D
OK Guy's
This is where I step in and clean everything up..
Man, I didn't want to read this thread but, here I am.....
Let me know if I missed anything.
Nick-