The rear wheel drive five speed transmission known as the RE5R05A is used in both Nissan and Infiniti vehicles as far back as 2002 to present time. Typically fitted behind 3.5L, 4.0L, 4.5L and 5.6L engines, this transmission is offered in both 2WD and 4WD configurations. As with many transmissions these days, this transmission is gear ratio sensitive. Similar in design to Mercedes 722.6 and the Dodge NAG1 transmission, the three planetary gear sets produce three different overall ratios. Due to the variety of vehicles this transmission finds itself in, there are various style gear shift options as well. The TCM that matches the vehicle’s calibration specifications is mounted on the valve body with the exception of first production Infiniti models.
With these mentioned variations alone, the ID tag is a critical piece of information when ordering parts or exchanging units. Of course we know that in real life this tag is never missing right? Or, if the tag is present, it guarantees that no one used incorrect planetary assemblies in the rebuild process right? Incredibly, mismatch parts and/or units do not occur with the frequency as one might assume. So when it does, it can catch you off guard. Whether the wrong planetary system is used or the wrong TCM, gear ratio errors are the immediate consequences. In some cases, shift scheduling is altered to earlier shift points, yet will not shift at wide open throttle until it hits the rev limiter. Gear ratio errors soon follow. With this transmission having several other issues that can cause gear ratio errors, infrequent mismatched parts or transmission combinations can sometimes take a shop several days to discover.
One issue that has plagued this transmission over the years is the engine coolant mixing with the transmission fluid. This problem is quickly identifiable as the transmission fluid looked like a strawberry milkshake. The same occurs with the RE5R05A yet it seems to depend on how much glycol has actually mixed with the fluid. Often times the vehicle comes in to the shop with a converter clutch slip or shudder problem. When the pan is dropped, the fluid may not be pink in color. A trained eye may notice that the filter bolts have some pitting to them or oxidation above the fluid line inside the transmission. In other cases there is visible rust or it’s just loaded with pink fluid.
Another telltale sign of glycol intrusion is that it destroys piston seals. The seals on the piston inside the aluminum direct clutch drum as seen in Figure 9 (photocompliments of John Parmenter from Centereach Transmissions), will expand so much, the piston will not come out requiring the need to obtain a whole new drum assembly. 5.6L vehicles have a different design direct clutch drum escaping this problem. However, in addition to piston seal failure, what all vehicles are subject to, regardless of engine size and design is TCM failure. This is critical to know when taking on this repair as TCM issues may not be readily present at the time of rebuild. Sometimes solenoid and/or pressure switch circuit fault codes are logged. If the tech is aware of possible glycol intrusion, the thought is, the water in the fluid has caused the codes. After repairs the codes clear and the vehicle is delivered. A day or two later the vehicle returns to the shop with the same circuit fault codes. In either case, it's an expensive lesson to discover that glycol was responsible for damaging the TCM after all repairs are done.Another costly scenario we have seen is when this glycol intrusion is not detected. The transmission is rebuilt and sent out. A day or two later it comes back with these circuit fault codes. The first loss is now realized when they discover that the TCM is defective. They do not know why it is defective; they just know that it is. A new one is purchased; it’s a plug and play computer, so down the road it goes. No codes, all works well. The problem is the radiator is still defective. It now slowly introduces glycol into the system. The newly installed TCM and transmission is on its way to repeat failure.
Besides a trained eye or strawberry milkshake fluid, how does one know if there is a glycol intrusion problem? One sure way is to test the fluid using a glycol kit such as the HI 3859 kit from Hanna Instruments. A poorer man’s method I have been told is to drip some fluid onto a hot plate. If there is smoke, no glycol, if it sizzled, you have glycol. I have also been told glycol glows under ultraviolet light.
Recently, I was able to obtain a defective radiator and valve body assembly from a local shop. Separating the bottom tank from the radiator is quite simple to do. It's just a matter of bending some tabs with a screw driver. Once the tank was removed, I was able to separate the cooler from the tank and decided to pressurize it. If there was a leak, I couldn’t hear it or see it, even when submersed in water. I then decided to go the opposite way and pull vacuum on the cooler. Surprisingly enough, I pulled near 25 inches of vacuum where it held for a few seconds before beginning a slow decent stopping at 5. Having now confirmation that there is an opening somewhere in the cooler, I began my search to find its location. So I decided to heat the cooler up to approximately 220 F monitoring the temperature with a temperature gun. To my amazement, it held 25 inches. To be sure, I repeated the test with a different vacuum pump, which confirmed the results. I then poked the cooler into a freezer for a couple of hours and tested it cold. Sure enough, it had a slow leak. The result of this test explained why in some rare instances this problem occurs slowly. In other instances the cooler fails more severely when hot rather than cold explaining the sudden and extreme intrusion of glycol.
A new radiator from Nissan cost approximately 225 dollars. This has caused some shops to buy an aftermarket radiator for near half the price. Some have bypassed the radiator completely installing an aftermarket auxiliary cooler. Both scenarios have caused converter clutch issues. If an auxiliary cooler is installed without any restriction, a loss of back pressure alters torque converter pressure. Although this is a 3 port converter design (one port to apply the clutch, one port to charge the converter and one as a return to the cooler), the charge pressure works against the piston that applies the clutch.
This piston does not have a return spring which would normally be calculated into the apply and release strategy of the clutch. Without a return spring, it now relies on torque converter charge pressure to do its job. Which means if this pressure is too low, it can result in affecting converter clutch apply and release functions.
Some after market radiators have a complete opposite affect. When the cooler inside the radiator reaches operating temperatures, cooler flow becomes overly restricted. This causes too much back pressure inside the converter causing issues with the apply and release of the clutch.
For 2005 to 2010 Frontier, Pathfinder and Xterra vehicles, Nissan has extended their warranty to eight years/80,000 miles. You can obtain information on how to file a claim through their web site www.nissanassist.com. If the transmission failed as a result of cooler failure and it was rebuilt, along with the replacement of an OE radiator and fluids, Nissan has been very good about paying the bill any where in the range of 40% to 100%.
A final predicament that needs to be addressed is when this transmission comes in to the shop for other reasons. The radiator has yet to fail. What do you do? Consider when it does fail. Besides rebuilding the transmission, it will require changing the torque converter, the radiator and the TCM. Why do this type of repair under warranty?
I suggest including a new radiator with all repairs. If not and it fails afterwards, you were the last one to touch the vehicle in the owner’s mind. At best, warn the owner before hand of the potential hazard. In this way you can be released from the damage it will cause when it does fail.
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