Pre-Installation Steps and Checks

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You MUST flush your coolers and lines with clean ATF prior to install.  Failure to do so can cause debris to get clogged in any number of places in the new transmission, causing any number of problems.

The large air-to-oil cooler in the front of the radiator is a "stacked plate" type unit.  These are very hard to flush since any debris will have sunk to the bottom of the cooler, and any flushing could pass right over top of the debris layer.  In the case of severe clutch damage as part of your trans failure, we recommend replacing this cooler with a new one.  Replacing with the large 6.0 cooler is not necessary, but replacing your 7.3 cooler with a larger v10 cooler is very easy and probably costs the same to replace.  2000 and up trucks will have a small transmission fluid heat exchanger in the bottom of the radiator.  This "cooler" is not removable, but it can be flushed much easier as the debris does not have gravity working in it's favor here due to the orientation of it.

A good shop uses a "Hot Flush" machine that bursts hot oil back and forth through the system.  This machine is not practical for the weekend warrior working on a driveway, but there are other methods.   You could use a small pump to force clean fluid in through one line and out the other into a bucket.  You could rig up some flexible lines so that you can pour clean fluid in through a funnel and collect the dirty in a bucket from the other end.  You could remove the air-to-oil cooler and flush it on a bench and then clean the lines separately.  To clean the lines alone, you could pour some clean fluid in and then blow that clean fluid through with compressed air.  No matter which method, it is best to alternate the direction of the flush.  If there is debris inside your coolers and lines, it will get blown into your brand new transmission immediately upon startup up.  The coolers are downstream of the filters!

Click the button for a video about the various cooler options.

To operate correctly, you must have a good wire harness.  Check all wires for chaffing, this normally occurs near the plastic plugs.  Repair as needed.  Check the plastic plugs for the snap retainers.  Over time the plastic gets brittle, and these things tend to break off.  If your speed sensor plug retainers have broken off, you can try some creativity with zip-ties, or order new ones (Auveco 19157).  Another common problem area is the plastic plug that snaps onto the solenoid pack (large connection on passenger side of trans).  The snapping tab can be broken off during removal.  If yours has broken off, you will need to find a way to hold the connection together, because this WILL work it's way loose and cause problems.  The DTR plug should also snap onto the DTR, if not, you will again need to find a way to secure it so it doesn't come undone.  If your harness requires more than a couple small repairs, it's probably time for a new one.

Before making any electrical connection, make sure each side of the connection (especially the truck-side) is clean using electrical contact cleaner. 

Shift linkage operability is extremely important.  There are a set of PRND21 shift detents in the steering column, and another set inside the transmission.  They must be in sync.  If not, you will not be fully engaged into any shift range.  In this situation, the clutch packs will not receive full pressure and they will drag until they burn up.  Also, you could even have trouble getting into PARK.

Click the button below for a video I made showing how to check and adjust your shift linkage.

It is much easier to install the torque converter with the transmission standing vertically. You will have to turn the TC back and forth to get it to “clunk” all the way down. To check, place a straight edge across the bellhousing.  When fully engaged, there should be about 3/16" between the bottom of the straight edge and the top of the TC-to-crankshaft pilot.

Click the button below for a video I made showing how to make sure your TC is seated.

Click the button below for a video on how to seal the transfer case to the transmission without the big gasket.

Expect a new empty stock system to take 17-18 quarts of oil (less for E4OD).  If you have a deep pan, or 6.0 cooler, you will need some more.  I presoak all bearings and frictions in Mobil1 Synthetic ATF (112980), but any MerconV compatible synthetic ATF will do.  There is no need to pour any fluid into the torque converter as it does not need to be primed.

Once trans is installed and everything is hooked up, and with a charged battery:

   Pour about six quarts in.  

   Start the engine, leave it in PARK, only let it run for 5-10 seconds.  Shut engine off.  

   Put another six quarts in.  

   Start the engine again, run for another 5-10 seconds, shut engine off.  

   Put four quarts in.  

   Start the engine and let it run.  

   Shift through all the PRND21 range positions a few seconds at a time with your FOOT ON   THE BRAKE.  

   Go back and forth two or three times through the range. You will gradually feel the truck start to pull.  

   Add fluid to correct operating level per the owner's manual instructions. 

You just filled and empty transmission with more than 4 gallons of oil, that means more than 4 gallons of air needs to come out.  You got most of it out during the Fluid Fill routine above, but there's more.  

Take a few 10-15 minute drives in areas with stopsigns, stoplights, and lower speed limits.  Use all the PRND21 shift ranges during these drives.  Head home, check the fluid level while it's warmed up and running, top off as necessary, and let the truck cool down for a few hours.  Do this drive routine a couple more times.  

During these drives you may experience hard shifts, soft shifts, other strange things.  This will all clear up as the last of the air is burped out of the circuits.

If you are going to be doing engine modifications that require custom tuning, be sure to tell your tuner that your transmission has line pressure improvements built into it.  If the tuner were to make large electronic pressure adjustments on top of what is built in, shifting could be very unpleasant.

A video explaining how to tell the 4r100 gas and diesel cases apart.

A video explaining the differences in the more common torque converters.

A video showing what is different about a PTO unit

How the bypass tube works.