Case 70XT Drive And Steering Problems

[MikePhua]

Case 70XT Model Background
The Case 70XT skid steer is a mid-2000s machine in the XT series, developed as a high-power, mechanical-control loader for construction, agriculture and rental fleets. It uses a turbocharged diesel around 80–85 horsepower, with an operating weight just under 7,000 lb and a rated operating capacity of about 2,000 lb.
The 70XT shares its engine family with larger Case models like the 90XT and 95XT. The XT series helped Case strengthen its position in the North American skid steer market at a time when overall annual skid steer sales were roughly in the tens of thousands of units across all brands. The 70XT earned a reputation for strong pushing power, thanks to:

• Hydrostatic drive
  
• Heavy-duty chain final drives
  
• High breakout force and robust frame
  

But like any hydrostatic machine, age, heat and contamination can cause drive and steering issues that show up as loss of power, weak turning and inconsistent response.
Initial Symptoms Loss Of Drive And Steering Power
The case described is typical of a “good-when-cold, bad-when-hot” hydrostatic problem:

• When first started from cold, the machine drives and steers fairly well, though it feels slightly sluggish compared with larger XT models.
  
• After about 15–20 minutes of work, the machine begins to lose drive and steering strength on both sides, forward and reverse.
  
• Eventually it can hardly move or turn at all.
  
• The loader arms drift down quickly, even when they should hold.
  

These clues are important:

• The problem affects both left and right drive equally.
  
• It appears with temperature and run time, not immediately at start-up.
  
• There is also noticeable loader drift, hinting at hydraulic leakage somewhere in the system.
  

This combination strongly suggests a systemic hydraulic or hydrostatic issue (pump, charge supply or internal leakage) rather than a single failed drive motor or a single side linkage problem.
Understanding The Case 70XT Hydrostatic Layout
Some key system concepts help make sense of the failure pattern:

• Hydrostatic pump
  A variable-displacement pump driven by the engine, feeding oil to left and right drive motors. As the swash plates tilt with the steering levers, the pump sends high-pressure oil to the drive motors to turn the wheels.
  
• Drive motors
  Hydraulic motors connected to chain final drives. Each side has its own motor transmitting torque through chains to the wheels.
  
• Charge pump
  A smaller pump that feeds make-up oil to the hydrostatic loop, maintains charge pressure, and supplies oil for control functions. If charge pressure falls, the hydrostatic system becomes weak or stops.
  
• Loader hydraulic system
  A gear pump supplies oil to the lift and tilt circuits via a main control valve. In the XT family, the drive and loader systems share a common reservoir and filtration but have separate pumps.
  

Because the drive on both sides gets weak as the machine warms up and the loader arms drift, the suspicion shifts toward common elements:

• Hydrostatic pump wear
  
• Charge pressure loss
  
• Internal leakage causing heat and pressure drop
  

Why Both Sides Are Weak At The Same Time
It is statistically unlikely for both drive motors to fail in exactly the same way at the same time. When both left and right drive become weak symmetrically, especially with heat, that usually indicates:

• Wear inside the hydrostatic pump’s rotating group (swash plate, pistons, barrel).
  
• Low charge pressure due to a tired charge pump, leaking charge relief, or clogged inlet.
  
• Severe internal leakage in the pump that increases with temperature, thinning the oil and reducing effective pressure.
  

Because the 70XT is powerful when healthy—experienced operators note that a good 70XT can spin on asphalt with a full bucket—anything less than crisp, aggressive turning is a sign of serious hydraulic performance loss.
Loader Drift And Its Relationship To Drive Problems
The quick downward drift of the loader arms is another useful diagnostic clue. Loader drift usually points to:

• Internal leakage across the lift spool in the control valve
  
• Leakage across the load-holding (counterbalance) checks
  
• Internal leakage past the piston seals in the lift cylinders
  

However, in the context of the 70XT’s other problems, loader drift also indicates that:

• The hydraulic system as a whole is not maintaining pressure effectively.
  
• There may be contamination or wear throughout the system, not just in one circuit.
  

It does not strictly prove the same component is causing both drive weakness and drift, but it supports the idea that the machine has seen enough wear and possible contamination that both the hydrostatic and loader systems have compromised sealing surfaces.
First Diagnostic Step Checking Hydraulic Pressures
Because guessing is expensive, the first practical step is a pressure test. On a 70XT, a thorough hydraulic diagnosis would normally include:

• Charge pressure test
  • Use the service ports recommended by the manufacturer to connect a pressure gauge.
    
  • Check charge pressure at idle and at rated rpm.
    
  • Typical hydrostatic charge pressures for this size of skid steer are often in the 250–350 psi range, but exact values should follow the service manual.
    
• High-pressure hydrostatic test
  • Load the machine (for example, pushing into a pile) while monitoring drive pressure.
    
  • Compare measured numbers to the specified system relief or stall pressure, often around 4,000–5,000 psi for machines in this class.
    
• Loader system pressure test
  • Tee a gauge into the loader valve inlet.
    
  • Cycle lift and tilt to relief and confirm pressure and stability.
    

If charge pressure is low and falls as oil warms, the charge circuit or pump is suspect. If high-pressure hydrostatic readings never reach spec even at full lever command, pump wear or relief mis-setting is likely. When loader pressure is also low or unstable, broader system problems or shared supply issues may be present.
Pump Condition And Rebuild Considerations
Experienced mechanics note that the 70XT hydrostatic pumps are not especially difficult to repair, but cleanliness and careful inspection are critical.
Key guidelines when rebuilding or replacing pumps:

• Work in an extremely clean environment.
  
• Inspect the following for scoring, pitting and abnormal wear:
  • Cylinder block and pistons
    
  • Swash plate surface
    
  • Valve plate
    
• Replace any worn bearings and seals.
  
• Carefully set swash plate neutral, following service procedures to avoid creeping.
  

Because the pump must be removed to access the drive motors on many XT machines, mechanics often recommend:

• Inspecting drive motors at the same time
  
• Pulling chain case drain plugs to check for oil contamination from leaking motor shaft seals
  
• Flushing the system and replacing filters once major components are serviced
  

This approach prevents installing a fresh pump into a dirty, contaminated circuit that could rapidly damage new components.
Chain Case Drains And Motor Seal Checks
On the 70XT, the final drives use heavy chain cases on each side. Each chain case has drain plugs that provide useful information:

• If the oil in the chain case is milky, there may be water intrusion, which can damage bearings and chains.
  
• If the chain case is overfull and smells strongly of hydraulic oil, one or more drive motor seals may be leaking into the chain case.
  

Leaking motor seals by themselves might not cause equal weakness on both sides, but they can:

• Lower the effective pressure available for drive
  
• Increase heat and contamination
  
• Accelerate wear in both pump and motors
  

Therefore, when diagnosing drive and steering problems on a 70XT, pulling the chain case drains is a straightforward and informative step.
Servo And Control Linkage Issues
The 70XT is a mechanical/servo machine, not pilot-control. That means:

• The steering levers are mechanically linked to servo units on the hydrostatic pump.
  
• Those servos convert lever movement into swash plate angle, which controls drive speed and direction.
  

Possible issues here include:

• Worn or misadjusted linkage causing lost motion or uneven response.
  
• Sticky servo pistons or internal leaks in the servo section of the pump.
  
• Binding or seized joints that make control stiff and inconsistent.
  

Servo or linkage problems more often cause:

• Unequal steering
  
• Jerky or hard-to-move levers
  
• Erratic behavior rather than uniform, heat-related power loss
  

Since the described machine loses drive equally left and right, and only after warm-up, servo problems alone are less likely but can coexist with pump wear.
Is It The Pump Or The Motors Or Both
A structured diagnostic logic looks like this:

• If both sides are equally weak, suspect the pump or charge system first.
  
• If one side is weak and the other is strong, suspect:
  • A single motor
    
  • A single side relief or directional valve issue
    
  • A mechanical linkage problem affecting only one side
    

In this case, because both sides lose power as the machine warms up, and there is also fast loader drift, the most probable root cause is:

• A worn hydrostatic pump, possibly combined with charge pressure problems
  
• Additional system wear from contamination or age
  

However, once the pump is out, it is economical to:

• Inspect both drive motors
  
• Replace seals
  
• Flush the system and chain cases
  

Skipping these steps risks repeated failures.
Cost, Risk And Rebuild Strategy
From a practical ownership standpoint, the owner must balance:

• Machine purchase price and current market value
  
• Estimated cost of pump rebuild or replacement, plus possible motor work
  
• Downtime cost
  

For a 70XT in fair cosmetic shape, a full hydrostatic refresh and system clean-out can be a good investment if the machine is needed for the long term. Many skid steer fleets report keeping hydrostatic machines profitably to 6,000–8,000 hours and beyond after major drive system work, provided the rest of the loader (frame, boom, pins and engine) is solid.
A sensible plan can be:

• Step 1: Perform pressure tests to confirm the pump is truly weak or charge pressure is low.
  
• Step 2: If confirmed, remove the pump and send it to a reputable hydrostatic shop or rebuild in-house with proper procedures.
  
• Step 3: While the pump is out, check the drive motors and chain cases, replace seals and bearings as needed.
  
• Step 4: Reassemble with fresh oil and filters, then repeat pressure tests to verify improvement.
  

A Short Story From The Shop Floor
Imagine a contractor who bought a used Case 70XT at what seemed a bargain. On the first cold morning, the machine drove acceptably, even if not as lively as a newer loader. The real trouble showed up after a half hour of pushing gravel: the machine could barely turn, and the arms settled on their own.
Initial guesses ranged from “bad motors” to “weak engine,” but a seasoned mechanic insisted on starting with pressure tests. The gauges told the story: charge pressure sagged badly as oil warmed, and full-stroke hydrostatic pressure never reached spec. When the pump came apart on the bench, deep scoring on the rotating group and a contaminated valve plate confirmed long-term wear.
The shop rebuilt the pump, resealed both motors, flushed the hoses and chain cases, and refilled with clean oil. Back on the job, the same 70XT spun around on hard ground with a full bucket—reminding everyone that when these machines are healthy, they are far from sluggish.
Preventive Measures To Protect Drive And Steering Performance
Hydrostatic systems age, but premature failure can often be avoided with disciplined maintenance:

• Change hydraulic filters and oil at or before the recommended intervals, especially in dusty or hot environments.
  
• Keep breathers and caps clean to limit contamination.
  
• Periodically check chain case levels and drain small samples to look for signs of hydraulic oil or water.
  
• Avoid extended operation with obvious performance problems; low charge pressure and cavitation can rapidly destroy pumps and motors.
  
• When buying used, factor a potential hydrostatic overhaul into the price if the machine shows any signs of heat-related drive loss or severe loader drift.
  

For the Case 70XT, which was designed as a strong, high-power skid steer, persistent weakness in drive and steering is not “just how they are” but almost always a sign of underlying hydraulic trouble that can be found, measured and corrected with a methodical approach.