M5OD Mazda Design Manual Five Speed Transmission Preventative Measure

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By Paul Grazier

Ok guys and gals here is a NOTICE for my fellow Ford truck lovers. I have found a warning concerning the Mazda M5OD transmission. This warning reads as follows:

M5OD Mazda Design Manual Five Speed Transmission
Those of you who own Ford full size or small size trucks with the M5OD Mazda design 5 speed manual transmission should have the rubber shift cover plugs resealed at your earliest convenience. A common occurrence with this model transmission is the rubber plugs shrink over time and allowing lube oil to leak out of the transmission. This occurs while the vehicle is in operation, so there is less of a tendency for a puddle to develop when the vehicle is sitting parked. The result to the transmission is a lack of lubrication and damage to some very expensive gears and bearings. This is a very prevalent problem.
Please get it taken care of before you are added to the casualty list.

The above warning can be found at this website:


If you haven’t fixed this problem I too suggest you do so as early as you can. I ran into this problem and noticed my M5OD was leaking fluid steadily when I was driving. A witness was able to confirm this as they drove along beside my truck. The transmission won’t leak if the truck isn’t in motion or in use. You can fix this problem yourself and it should take you around a day to do so. I did so because every autoshop I called wanted $260 to $285 to replace $10 worth of parts (a set of three rubber plugs).

Here is a list of items you will need to perform this repair.

  • The three rubber shift plugs that need to be replaced. Your local Ford dealer is the only place to purchase them.
  • Silicon gasket sealer.
  • Thread lock.
  • A set of Torx screw drivers. Can be found at any Wal-Mart for a cheap price. A Torx screwdriver has an end that looks like five pointed star.
  • 12mm socket and socket wrench.
  • Couple cans of brake Cleaner. (Works very good to remove dirt and grime)
  • 4 quarts of Dexcron III Mercon ATF fluid.
  • Can to hold bolts.
  • Here is what I did to fix this problem:

  • Put the transmission in 1st gear. DO NOT PUT THE TRANSMISSION IN NEUTRAL! First remove the shift boot. Four screws hold this to the floorboard. Do this gently as the plastic is easy to break and you don’t what to tear the shift boot or the sound dampening pad under the shift boot. Gently pull up on the shift boot and the sound dampening pad to see the Torx screws that hold the gear shifter in place. There are three Torx screws that hold the gear shifter to the transmission. Remove the gear shifter by unscrewing the Torx screws. Once you have the three screws removed, pull up on the gear shifter.
  • Take off the driver side and passenger side kick panels and the carpet edge protectors located on the floor by each door. Four screws hold down each carpet protector. Three plastic nails with splines secure each kick panel. In between the dashboard and the front side of each door is a screw that needs to be pulled out to aid in the removal of the kick panels.
  • Pull back the floorboard carpet onto the bench seat or seats.
  • You will now have to remove a panel on the floorboard that covers the transmission. This panel has been bolted and glued to the floorboard. Brake Cleaner will dissolve the glue but be careful, using to much brake cleaner will dissolve the glue into a slimy sticky mess. You only want to “loosen” the glue. To remove the panel after unscrewing the bolts, use a flathead screwdriver to pry up the panel. Be careful, as this panel will bend / contort if you use too much pressure. Take your time and work steadily.
  • Once you have the floorboard panel removed, you will be able to see and access the transmission. On the top backside of the transmission you will find the three rubber plugs that need to be replaced and sealed. To get to them you will need to remove the top cover of the transmission, which is held in place by 10 bolts. Before you remove the bolts make sure to clean the top of the transmission thoroughly with brake cleaner. YOU DON’T WANT TO GET ANY DIRT IN THE TRANSMISSION!
  • Remove the bolts and slowly pull up on the transmission’s top cover. Make sure you pull straight up on the cover. After removing the top cover, cover the transmission with a clean towel to prevent anything from falling into the transmission.
  • Once you have the top cover off, you can remove the old rubber shift plugs and install the new ones. Be careful with the shift linkages on the underside of the transmission’s top cover. You don’t want to knock the linkages out of alignment with 1st gear or break the gear grapplers. Make sure to clean each hole for the plugs. Before installing them, apply a generous amount of silicon on each new plug. Make sure you place the silicone all the way around each plug so a good seal will be made when you install it. Do this for all three plugs.
  • Set aside the top cover and allow the silicone to set for a few minutes This will give you the opportunity to inspect the inside of the transmission. Check the gears for the following defects:

      Chipped teeth – which is caused from grinding the gears while shifting.

      Gears with blue and brown teeth – an indication the gears are getting very hot and the transmission is low on oil.

      A large amount of metal particles – an indication of excessive mesh and wear, which is also caused by a transmission that, is low on oil.

      Check the racer bearings located at the front and back of the gear tree. If they look worn or are loose, they can cause future problems with the transmission.

    If you find any of the mentioned problems, you may want to review your driving habits and/or get your transmission repaired. Otherwise you shouldn’t find any metal particles in the AFT fluid or on the inside of the transmission case. If you do a lot of towing expect to find the magnetic stud on the transmission drain plug to be covered with ultra fine metal particles. Drain the ATF fluid from the transmission and make sure to thoroughly clean the magnetic stud on the drain plug. Pour the four quarts of Dexcron III Mercon ATF into the transmission from the open topside. Your transmission will love this addition of fresh oil!

  • Now you’re ready to install the transmission’s top cover. Make sure the underside of the top cover is clean and the rubber gasket is in good condition, in place and has no dirt on it. If the rubber gasket is torn, broken, or dried out anywhere, GET IT REPLACED! To install the transmission’s top cover, align the two gear grapplers located on the underside of the cover with the races located on the gear tree. The cover will go on only one way and you also have two studs located on the transmission’s top cover to help guide you. One is located on the front right side of the cover and the other is located on the back left side. Take your time and work slowly. If you have the gear grapplers aligned with the races on the gear tree, the top cover will go on with little effort.
  • Once you have the top cover on and it has made a complete seal with the transmission you are ready to bolt it down. MAKE SURE THE TRANSMISSIONS’S TOP COVER HAS SEATED FLUSH WITH THE TRANSMISSION! Apply thread lock to the bolts to make sure they don’t come loose. You are doing this because transmission gears produce high pitched radial noises, which will vibrate a bolt so much it will come loose. The bolt won’t come out, but the side it holds down won’t make a complete seal.
  • Install everything else in reverse order. Install the floor board panel for the transmission, lay down the carpet, install driver side and passenger side kick panels, install the carpet edge protectors on the floorboard by each door and finally install the gear shifter. Remember the two screws you pulled out to remove the kick panels? Put them back too!
  • Most silicon gasket sealant requires 24 hours to set. Don’t drive your truck during this period, as the oil inside the transmission will defeat the silicon gasket before it has a chance to set and do its job.
  • This will save you expensive repairs in the future and give your M5OD transmission a long and repair free life!
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