47RE Pump Bushing Replacement Guide: Symptoms and the Fix

If your 47RE is leaking out the front, dropping line pressure when it gets hot, or throwing torque converter clutch codes that no solenoid seems to fix, stop chasing the valve body for a minute and look at the front pump. The pump bushing is a cheap, unglamorous part that quietly controls whether the turbine shaft runs true, whether the front seal can seal, and whether the pressure regulator valve can stay in balance. When it wears, it takes expensive parts down with it.

This is the diagnosis and replacement guide for the 47RE pump bushing on 1995-2003 Dodge Ram Cummins trucks.

What the 47RE pump bushing actually does

It is not just a spacer. Per Sonnax's tech article on 46-47RH/RE cooler and converter flow, the pump stator supports and aligns the turbine shaft with the center of the converter cover. On the opposite side of the cover is the crankshaft pilot. The cover bushing centers the turbine shaft by way of the turbine hub, and that centering controls release oil flow. Sonnax is blunt about the consequence: if that bushing or the crank pilot is worn, the turbine shaft sealing rings can cross leak, which directly affects TCC apply and release oil. Sonnax makes the same point in its converter troubleshooting material: internal bushings ensure the turbine shaft runs true, a requirement for the sealing rings to seal at all. A worn bushing does not just wear. It breaks the seal geometry of an entire hydraulic circuit.

Bushings in an automatic live a hard life. Sonnax notes they are designed to support loads up to 1,400 psi and survive temporary operation with low or no lube oil. There is not much margin built in.

Symptoms of a worn 47RE pump bushing

• Front seal leak that comes back. You replaced the seal, it leaked again. The bushing lets the converter hub move off center, and the seal cannot follow it.
• Low line pressure, worst when hot and at idle. Sonnax's pump/PR/converter analysis lists "any unit with weak/worn pump or excessive internal leaks" as a cause of low balance pressure at the pressure regulator valve.
• TCC codes and TCC slip. Sonnax's 46-47RH/RE article names 740/1740 codes, TCC slip at high torque, delayed engagements, slow converter fill, excessive stall speed and hydraulic noise as the cluster of complaints tied to this circuit.
• Rising trans temp with no obvious cooler problem. Internal leakage past a worn bushing consumes pump volume that should be going to the cooler and lube circuit.
• Whine or hydraulic noise that changes with load.

Why low pressure and a worn bushing feed each other

This is the part most people miss. According to Sonnax, the pressure regulator valve limits pump output down to the common 50-250 psi range seen in transmissions, and it also acts as a priority valve: it gives priority to line pressure and less priority to converter and lube pressure. If the pump cannot maintain line pressure, the PR valve moves "out of balance" and converter charge and lube oil get restricted, sometimes cut off entirely.

Sonnax describes exactly the scenario a Cummins owner lives in: a diesel truck lugging a load up a long incline, low RPM and high desired line pressure. You can have near-normal line pressure and clutch holding capacity while cooler and lube flow drops to almost nothing. Sonnax flags fixed-displacement gear-and-crescent pumps as a particular concern, since they have lower output at low RPM and idle. The most demanding condition for a pump is hot, at idle, in reverse.

So a worn bushing bleeds volume, the PR valve falls out of balance, lube flow drops, and the next bushing and the converter cook. That is the failure chain.

How to diagnose it before you pull the trans

1. Run a line pressure test first. Get real numbers hot and cold, in Drive and Reverse, before you condemn anything. Our 47RE and 48RE line pressure test procedure walks through where to tap and what the readings tell you.
2. Rule out the cooler circuit. Sonnax calls cooler restriction by far the most common issue on these units, and notes the effect can become a problem as head pressure nears 80 psi or more. Sonnax's recommended verification is to temporarily bypass the cooler circuit and re-test. Check the drainback fitting and the lines.
3. Pull the inspection cover and look. Fresh fluid inside the bellhousing points at the front seal and, behind it, the bushing.
4. Read the wear pattern once it is apart. Builders use a rule of thumb here, offered as field experience rather than published spec: crank or case offset tends to wear the converter hub all the way around while the pump bushing wears on one side; converter hub runout does the reverse. Either way, inspect the converter neck for grooves before it goes back in.

The fix: bushing, or complete pump?

If the pump body and bore are clean and the only damage is the bushing, replace the bushing. If the bore is galled, the stator is scored, or the gears show wear, the smart move is a complete pump assembly. You are already paying the labor to have the unit out.

Either way, the pump has to come apart and the front seal and pump gasket get replaced. We stock complete pump assemblies for the 47RE, 46RE and 48RE in the transmission pumps collection, and the soft parts you will disturb getting there in gaskets and seals.

Bushing selection and installation, per Sonnax

If you are replacing just the bushing, Sonnax's bushing guidance is worth following to the letter:

• Skip anything that is not steel-backed. Sonnax says in most cases to forget non steel-backed bushings; lower fatigue resistance, worse retention, and they can distort during installation.
• Understand the material. Lead/tin babbitt is soft, with poor fatigue resistance that worsens as temperature rises. Copper/lead bronze has high fatigue resistance. Aluminum is a bad choice anywhere lube is not immediate and continuous: once the thin surface coat is damaged, the exposed aluminum seizes rapidly.
• Do not drive it in with a hammer. Sonnax is explicit: precision bushings distort under shock loads. Use an arbor press and a dedicated installer. Lightly lube the bushing before pressing.
• Prep the surfaces. Sonnax gives real targets: bushing load surface under 25 micro-inches RMS, shaft journal 8-12 RMS, housing bore 60-125 RMS. Their grit chart puts 400 grit at roughly 10 RMS for the shaft and 60 grit at about 98 RMS for the housing. Kiss the surface, do not remove material.
• Clean every lube hole afterward. Sonnax calls dirt the worst enemy of a bushing.

Replace while you are in there

The transmission is out and the converter is off. Do not put worn parts back behind a new bushing:

• Front pump seal and the pump-to-case gasket
• Turbine shaft sealing rings, since a worn bushing was likely letting them cross leak
• Torque converter, or at minimum a hard inspection of the hub for grooves and runout
• Full overhaul gasket and seal set, since you are opening the case anyway
• Address the cooler restriction you found in step 2, or you will do this again

Sonnax also lists a line-to-lube valve for RWD Chrysler units (part 22771A-02K) that keeps oil flowing to the converter charge and lube circuit even when the PR valve goes out of balance. Worth a look if your truck tows heavy or idles hot.

Effort and difficulty

Pressing a bushing is a ten-minute job. Getting to it is not. The transmission has to come out, the converter comes off, and the pump has to come out of the case, so plan the same access work as a rebuild teardown. Nobody should pull a 47RE for a bushing alone: if it is far enough gone to leak or drop pressure, treat it as a teardown and inspection, not a single-part swap. An arbor press and proper bushing drivers are not optional if you want the repair to last.

If you are going all the way in, our 47RE rebuild guide covers the rest of the unit, and the Dodge and Cummins transmission parts collection has the hard parts and kits for the job.

FAQ

Can I replace the 47RE pump bushing without pulling the transmission?
No. The bushing lives in the front pump, which sits behind the torque converter at the front of the case. The unit has to come out.

Will a new front seal fix my leak if the bushing is worn?
Usually not for long. The bushing is what keeps the converter hub centered in the seal. If it is worn, the new seal gets the same off-center hub working against it and fails again.

Does a worn pump bushing cause TCC codes?
It can. Sonnax's 46-47RH/RE article ties a worn cover bushing or crank pilot to turbine shaft sealing ring cross leak, which affects TCC apply and release oil, and lists 740/1740 codes and TCC slip among the resulting complaints. Diagnose the cooler and valve body too, but do not rule the bushing out.

Sources

• Sonnax, "46-47RH/RE Cooler and Converter Flow," Bob Warnke
• Sonnax, "Bushwhacked! Keys to Avoiding Preventable Bushing Problems," Brian Wing
• Sonnax, "Anatomy of a Transmission: Oil Flow in the Pump-PR-Converter-Cooler Lube Circuits," Gregg Nader
• Sonnax, "Converter Conundrums"
• Sonnax Sure Cure Kit SC-46-47RHE-OS contents and applications
• Builder field reports on converter hub and pump bushing wear patterns (anecdotal)