Keep Those Trannys Rolling - June - 2020

ZF8, Just in Case

In this issue of “Keep Those Trannys Rolling”, we are going to take a look at a 2016 Land Rover Range Rover with a 3.0L engine and a ZF8HP70 transmission that has a persistent transmission leak.

According to the customer, his Range Rover had been to several shops for a persistent transmission oil leak, but no one seemed to be able to fix it. The customer had copies of several repair orders indicating that the transmission output seal and transfer case input seal had been replaced several times, but the transmission continued to leak.

Initial Inspection:

During the initial inspection of the vehicle, there were signs of oil residue on the rear of the vehicle. A couple of drops of oil had already dripped onto the ground. We then drove the Range Rover onto the rack so we could inspect the underside of the vehicle.

Underside Inspection:

With the vehicle raised up on the rack, we found the entire underside of the vehicle was covered with oil. After a thorough cleaning of the underside of the vehicle, we started the engine and allowed the transmission to reach 110°F, so we could check the transmission and transfer case fluid levels. During the fluid level check, we found the transfer case oil was full, but the transmission fluid was low. We refilled the transmission to the proper level and installed the fill/ inspection plug.

Duplicate to Diagnose:

With the transmission refilled we headed out for our test drive to see if we could duplicate the leak. During the test drive we paid close attention to the way the vehicle drove and the way the transmission operated. The vehicle seemed to operate properly and the transmission shifted through all of its gears normally as well. Everything seemed to be okay, so we headed back to the shop to take another look at the underside of the vehicle and determine the source of the leak.

Source of the Leak:

With the vehicle raised up on the rack again, we found oil leaking from what appeared to be a weep hole, located between the transmission and transfer case. With the source of the leak being located at the transmission-transfer case weep hole, it was time to remove the transfer case and inspect the transmission output shaft seal and transfer case input shaft seal for leaks.

Transfer Case Removal and Inspection:

After removing the transfer case assembly, we found the area between the transmission and transfer case was covered in oil, which made it difficult to determine which seal was leaking. With the transfer case fluid level being full, and the transmission fluid level being low, and having it to be refilled, we were pretty certain that our leak was coming from the transmission. So, we set the transfer case to the side and cleaned the transmission output shaft area. After a thorough cleaning of the output shaft seal area, it was obvious to us that the transmission output shaft seal had previously been replaced (as indicated on the customer’s repair orders). We knew we needed to take the time to really investigate this leak, and not just throw another set of seals at it.

The Investigation Continues:

With the transfer case removed from the vehicle, we started the vehicle and allowed the transmission to idle through its upshifts. We didn’t want to raise the engine RPM during the upshifts with no load on the transmission. Inspecting the transmission output shaft seal area, we noticed a slight leak coming from a case pocket just right of the output shaft seal. We cleaned the pocket area and watched as fluid continued to seep out. We then turned off the engine and re-inspected the case pocket. During the inspection, we found a very slight pin-hole in the case. Using a pick, we poked at the pin-hole and were able to enlarge it (figure 1). It was obvious to us that this was a case porosity problem. The question was…how are we going to repair it?

The Fix was in Sight:

Back in 2017, Land Rover issued several bulletins and special service messages to their dealership regarding this concern. There is a repair procedure for the case instead of replacing the transmission assembly.

The Fix:

Land Rover has an insert that is to be epoxied into the transmission case pocket to seal off the hole in the case. The transmission case insert part number is LR133314 (automatic transmission insert), and the special epoxy part number is LR125418 (Devcon putty), both being available from your local Land Rover Parts Department. The procedure is quite simple:

  1. Warning: safety goggles, protective gloves and mask must be worn during this procedure
  2. Clean the affected area using a suitable solvent-based cleaner
  3. Tape off areas not being epoxied (finished surfaces & output shaft)
  4. Mix Devcon: 4 parts resin/1 part hardener
  5. Fill affected case pocket with mixed putty, applying an even layer
  6. Cover insert with Devcon putty and insert into case pocket
  7. Fill the insert with Devcon putty until the insert is completely covered
  8. Allow at least 8 hours for Devcon putty to cure

zf8 figure 2Once the Devcon putty has cured (figure 2), install the transfer case, and refill the transmission with fluid. Test drive the vehicle for a lengthy amount of time and then recheck the weep hole for leaks. If there are no leaks, you can return the vehicle to its owner, knowing that you were the hero today.

Moment for Thought:

According to Land Rover bulletin # LTB01296NAS1, dated June 18, 2019 there are approximately 250,000 2015- 2016 Discovery, LR4, Range Rover, Range Rover Sport models equipped with the ZF8HP70 transmission that may be affected by this concern. Land Rover is not the only manufacturer using the ZF8 transmission. We will probably see a few of these. With some initiative and the right information, you should have no problem “Keeping Those ZF8 Trannys Rolling” down the road.

(special thanks to Land Rover for repair process and pictures)