Engine Mounted Shell and Bundle Coolers
PosiTech® International manufactures, remanufactures and rebuilds shell and tube bundle oil coolers for applications such as Caterpillar, Fiat-Allis, Detroit Diesel, Terex, Komatsu, Cummins, International, Mack, Ford, John Deere, Hyster, Michigan, and others. Shell and tube bundle oil coolers are available for torque converter, brake, engine, transmission, hydraulic, retarder, and other applications. PosiTech® International has the capacity to manufacture or service almost any style oil cooler.
Our rebuilt and remanufactured oil coolers can save our customers 70% off the cost of new, while offering our customers a more inclusive warranty than new. In effect, we take all the direct cost risk and you get 70% savings.
We use a high tech, specially designed process and one of a kind equipment to assure our customer of the highest quality.
Remanufactured vs. Rebuilt
PosiTech® defines a remanufactured item as one where we replace a major component with new, while still using part of the original unit. In the case of shell and bundle oil coolers we define a remanufactured unit as one in which we replace and build a new tube bundle and use the original housing. We remove each bundle from each housing to inspect and replace the bundle if necessary. This also allows us to use induction heaters to bake out any impregnated oil which is trapped in the cavities of the casting. This ensure a high quality braze joint upon reassembly.
With a remanufactured unit you receive all the benefits of a new unit, while saving money because we will reuse your existing housing. Most failures are in the tube bundle from tubes leaking due to baffle to tube wear, or headers being damaged from water hydraulics. If there is a failure in the system contaminants can get trapped in the bundle. Our new bundles we exceed the tube wall thickness of the original OEM. We re-engineer each unit so it has the same number of tubes, the same baffle count, the same baffle spacing and the same baffle cut. This is critical. If the baffle spacing or count is wrong, this will negatively impact either the cooling of the unit of the flow and back pressure.
Obsolete and Hard to Find Coolers:
Another advantage of our process is that we are able to remanufacture almost any shell and bundle oil, transmission, brake, or hydraulic cooler. As long as your housing is in good serviceable condition, we can re-engineer your unit. Our in house CNC machines and custom tube cutters allows us to custom build almost any brazed in tube bundle to remanufacture your unit. You nor your customer will not have to buy expensive plumbing kits. No need to junk a good machine just because the OEM will no longer service it. Call us today, and we can provide you a quote to remanufacture your unit.
A rebuilt item is one where we replace less than 20% of the original unit with new. In the case of a shell and bundle oil cooler, a rebuilt unit is one where we are able to reuse both the original bundle and casting, but may replace up to 20% of the tubes with new and still define the unit as rebuilt.
This is much more than just a flushing and leak test. Just like our remanufactured unit, each bundle is removed from the housing. We remove each bundle from each housing to inspect and replace the bundle if necessary. This also allows us to use induction heaters to bake out any impregnated oil which is trapped in the cavities of the casting. This ensure a high quality braze joint upon reassembly.
We use eddy current technology to measure the amount of tube wall which is remaining in your bundles. A leak test tells you if a tube leaks. Our eddy current technology tells us if a tube is too thin. A tube which is too thin may not leak now, but we can replace the individual tubes that are getting ready to leak in the near future. Being able to measure which tubes do not leak today, but are primed to leak in the near future, and being able to replace an individual tube if necessary, is one of the many aspects that separates us from a clean and flush. Your customer receives a high quality unit at a fraction of the cost of new, and you receive he peace of mind knowing you supplied your customer with the highest quality replacement available. note: neoprene headers do not lend themselves t being rebuilt. We only offer remanufactured replacements.
Please read below to see more on how we can help you meet your customer's needs, as well as some of the most common failures for a shell and bundle cooler.
Most Common Failure Modes:
Tube Wear Specifications
There are no OEM specifications for the minimum tube wall of a tube. We had a NASA compliant lab take samples of tubes and make precision cuts into different tubes, then run pressure and cycle tests on tubes with different simulated wear patterns. We then compared the durability and strength of a tube with wall specifications of .018”, .017", and .016” and so on until we found where there was a significant difference in the expected strength of that tube.
Tubes that do not pass specifications should be removed and replaced with our .018“ wall tubes. Everyone knows that braze flows toward heat. Once heat to braze in a new tube is placed on the header, braze around the surrounding tubes is impacted. To make sure that braze has not flowed away from the surrounding tubes towards the replaced tube, the entire header should be re-flowed.
Do not allow tubes in your bundle to be soldered off. This can impact the amount of water that flows through the tubes. If enough tubes are soldered off, then the oil, brake, or hydraulic fluid that passes around the tubes will not be sufficiently cooled.
The headers or tube sheets also need to be inspected for hydraulic damage. One would be surprised by the number of coolers that had something in the water supply that was larger than the tubes and just kept beating on the headers. Contaminants can give the same results as sand blasting, causing the strength of both the header and the tube to header bond to be compromised. If this is not corrected, then your cooler may prematurely fail.
Baffle displacement is a frequent condition that is seen in older units. We had one customer call and say that the oil cooler didn’t leak, but then every time they put the cooler on the equipment the engine overheated. We disassembled the cooler and found that the 7 baffles that were to be evenly spaced in a 20” cooler had dislodged and all 7 were in the bottom 5” of the bundle. The customer was getting no flow through the cooler. The pump was working harder because of the increased backpressure, the cooler was not working properly and the engine was running very hot.
With the bundle removed from the housing the rest of the bundle can be inspected. Contaminants can be removed. Baffles that have worked themselves loose can be repositioned to ensure proper cooling and operation of the cooler.
Tube to Baffle Vibration
Tube wear generally results from tube to baffle vibration. This is from the force of the oil pumping through the cooler, especially at surges, moving the baffle slightly. Most baffles are made of steel, most tube copper. Steel being harder than copper, will eventually wear a hole in the tube. High copper-oxide readings in an oil analysis can indicate that the copper tube is starting to be worn through due to baffle vibration.
We will reposition the baffle to a fresh area that will then eliminate future baffle movement. If the cause of the wear is not removed, then a failure is imminent.
Copper Tube Corrosion
Corrosion is caused on the copper tube by some sort of an additive or something in the oil reacting with the copper tube. Over time the corrosion of the copper could cause the tube to leak.
The technology is available to cut cost by 30% to 70% per unit, savings that can go to the bottom line. As long as your housing is in goo shape, we can remanufacture you a new cooler and re-braze it into your housing, providing your customers with a solution to any of the above issues, at considerable saving. Should you have any questions, please feel free to contact PosiTech at (800) 367-1374.
How We Provide you and You Customer with Peace of Mind.
A unit is received and identified. If the unit is sent from a customer we compare the packing list to what was actually received - any differences are noted and sent to the customer for verification. Units are stamped with a customer location and serial number.
The unit is then sent through a multi-step pre-cleaning process. The process includes specially formulated chemicals, detergents, soaks and flushes. The pre-cleaning process is intended to remove all oil, grease, and heavy contaminates. All units are then sent to disassemble the bundle from the housing. Given the dissimilar metals, we use a specially designed induction machine to ensure the even expansion and contraction of the bundle to housing.
IMPORTANT - Not being able to uniformly expand the unit causes a slight deformation of the bundle to housing unit. Braze requirements call for joint clearance of .003" to .005" for maximum braze strength. Non-uniform methods of removing the bundle from the housing will result in less than optimal clearances upon the reassembly of the unit. This can lead to field failures.
Next we bake all housings to remove any impregnated oil within the housing.
IMPORTANT - failure to remove the impregnated oil will weaken the braze joints upon reassembly of the unit. This can lead to field failures.
Bundles are then checked by our in-house check list to see if the bundle is a candidate for rebuilding. One of our checks is testing of the tube wall by our eddy current machine. This machine quantify us how much of the original tube wall has been removed and how much remains. Anyone can tell if there is a hole in a tube with a simple air under water leak test. We can tell if a tube which originally had .016 tube wall is now down to .005, .009 or .011 of the tube wall remaining.
If less than 20% of the tubes fail under our specification for minimum tube wall for a given unit, we will replace the defective tube(s) and the re-flow of the header. Next we will verify all baffles are in their proper location for the given part number. Last, we anchor baffles to tubes to significantly reduce the number one cause of bundle failure - a wearing of the tube by the baffle.
If the bundle is not able to be re-built, we build a new bundle. We can customize a tube pattern, baffle size, baffle position, to match any pattern by any OEM. Most OEMs call for tube wall specs from .012" to .018". All PosiTech® bundles are built with .018" tubes.
IMPORTANT - The braze used on your bundle makes a difference. Over the years some competitors have been supplying bundles brazed with Sil-phos. The advantage is that sil-phos is about 1/3 the cost of silver braze. In the correct end use application, Sil-phos is perfectly acceptable. But if the end use application uses engine oil or transmission fluid, the phosphorous in the Sil-phos will react and cause a chemical erosion of the copper tubes. All PosiTech® bundles are brazed with silver braze to allow for any end use application.
Rebuilt bundles are sent through a series of cleaning steps using specialized equipment that ensures all contamination is removed. Housings are inspected for overall length gasket seal flatness, and bolt holes are torqued to OEM specifications.
Bundles and housings are reassembled using an induction machine to again assure our customers of the highest strength - and quality - possible.
All units are then run through a series of cleaning processes, flushes , and multiple leak tests under conditions that simulate the entire work cycle of the unit. All serial numbers are recorded - the file includes the name of each operator who performed any function on the unit, batch numbers of all the component materials and dates of each step. Units are then painted and sprayed with a protective coating.