RAM ProMaster Water Intrusion Equals Transmission Failures

We have been seeing many transmission failures due to water intrusion on Ram ProMaster vans equipped with the 62TE transmission. One customer that came in was on his second failed unit due to water intrusion, so this led us to do some additional research to determine how this had happened twice to the same vehicle when he had never driven in flood waters or anything of that nature.

Out of the past six full-sized Ram ProMaster vans we have had in our shop, four of them have had water intrusion related failures. This is not caused by a failed radiator as the ProMaster only has an external transmission cooler. After looking over the vehicle and the design of the wiper cowl, online research revealed that water is entering the unit through the transmission vent cap, and/or the manual shaft bushing that is either worn or split. Three common issues are causing this to happen. The first major problem is that there is a large drain hose under the wiper cowl. This hose is often found knocked off with a loose clamp. (Figure 1)

I have also seen a few with the tubes missing altogether, leaving a large diameter drain that is pointed almost directly over the transmission vent cap/manual shaft. When water runs down the windshield it comes out of that drain and splashes into these areas causing a substantial amount of water to enter the unit over time.

The second common cause of the water intrusion is caused by the split in the wiper cowl itself; this is a two-piece cowl that has a foam strip in the center. This foam can wear down and fall out. When that happens, water drains down onto the top of the intake plenum. This causes water to puddle on the intake and water will run down the front; it can find its way down to the transmission vent / manual shaft when the rain is heavy.

The third most common problem is the drain tube for the wiper cowl is round at the top and then misshapen to oval at the bottom. (Figure 2)

If the customer parks in an area with tree limbs overhead, leaves and other tree debris can plug this drain. This causes the wiper cowl to fill up with water and this makes the split in the center of the cowl leak onto the intake plenum profusely.

When diagnosing these ProMaster vans, we are noticing multiple symptoms and codes. One had a shudder when the torque converter clutch was being applied; another slipped badly on take-off. One had no reverse at all. Also, we are seeing the PRNDL signals are sometimes erratic on the scan tool. They will show correct readings on the shifter assembly and the instrument cluster but will not read properly on the scanner. When we see these types of symptoms, we take a fluid sample out of the unit and get it ready to test.

We test the automatic transmission fluid by pouring it onto a hotplate looking for bubbles. The hotplate is set to 300°F, and once it is warmed up to the temperature, we pour the sample. When water is present the fluid will bubble and will make a crackling/popping sound. When you see this, you know it has water inside the fluid. Usually when we pull the pans to inspect, we can see a separation on the bottom of the pan where the water and oil have started to separate after sitting awhile. When these units fail from the water intrusion, we have noticed a few with large amounts of clutch debris in the external cooler. Many times, when we see this, there will be several little chunks of clutch material all over the spring and down inside the bore of the thermal bypass valve. This will need to be taken apart and cleaned very well. Also, if you do not have a good, heated reversing cooler flush machine, replacing the external cooler is strongly recommended due to how hard it is to get these little chunks of clutch out of the cooler.

Our solution to correct these water drainage issues is to remove the factory pinch clamp on the drain tube and replace it with a good aftermarket worm-gear clamp. When the tube is off, we blow compressed air through the tube to make sure there is no blockage in the drain that would cause a backup of water. If the foam strip in the middle of the cowl split is missing or completely worn out, we seal the seam with a good-quality black RTV silicone. Performing these actions seems to correct the issues that cause the water to enter the transmission. Now, whenever a ProMaster van comes into our shops for just regular services or a wellness checkup, we always check these cowls and drain and inform the customers of what can happen if this tube is ever left off.

On a side note, one last thing to mention on these vehicles is that when replacing/R&R these transmissions, it is required to change the bolts for the left side mount. These are single-use bolts and are not intended to be reused for safety reasons. TSB 23-022-19 states that 2014 through 2020 Ram ProMaster vehicles all require new bolts; this applies to all 1500, 2500, and 3500 models. Be sure to look up any that you are doing to see if newer years require the same bolts as the earlier models.

As it has been said, "An ounce of prevention is worth a pound of cure." Addressing manufacturer engineering mistakes before they cause expensive problems is a perfect way to add value to your customers' visit.