10-16-2025, 09:54 PM
The Ford 555B and Its Diesel Injection System
The Ford 555B tractor-loader-backhoe, introduced in the late 1970s, was part of Ford’s push into durable, mid-sized construction equipment. Powered by a 3-cylinder diesel engine, the 555B became popular for its simplicity, mechanical reliability, and ease of service. By the early 1980s, Ford had sold tens of thousands of these units across North America, with many still in operation today.
Central to its performance is the fuel injection system, typically equipped with either a CAV DPA rotary pump or a Simms inline pump, depending on production year and regional configuration. These pumps are responsible for metering and delivering fuel to the injectors under high pressure, synchronized with engine timing.
Symptoms of Fuel Dilution and Suspected Pump Failure
One of the more serious issues that can arise in older diesel engines is fuel dilution in the crankcase oil. This condition occurs when diesel fuel leaks into the engine oil, reducing lubrication and potentially causing catastrophic wear. In the Ford 555B, this is often traced to:
Pump Removal and Timing Precautions
Removing the injection pump from a Ford 555B requires careful attention to timing and access. While some believe the pump can be removed without disturbing the timing gear cover, the reality depends on the pump type:
Rebuild vs. Replacement Options
When a pump is suspected of internal failure, rebuild is often preferred over replacement—unless the pump is seized or extensively damaged. Rebuilders caution against shops that default to replacement without teardown. A proper rebuild typically costs $650 to $750, while new or aftermarket pumps range from $700 to $1,700, depending on origin and part number.
The pump in question, marked 3238F341, is part of a series where the final digit may vary. Compatibility is based more on application and flange type than exact number. Reputable suppliers can cross-reference pump numbers to confirm fitment.
Aftermarket Sources and Regional Support
Operators seeking affordable replacements have found success with:
Conclusion
Fuel dilution in the Ford 555B’s diesel engine is a serious issue, often linked to injection pump seal failure. With proper diagnosis, careful removal, and attention to timing, the pump can be rebuilt or replaced without dismantling the entire front end. Operators are advised to seek rebuilders who understand the pump’s internals and avoid unnecessary replacements. With the right approach, even a 1979 model can be restored to dependable service.
The Ford 555B tractor-loader-backhoe, introduced in the late 1970s, was part of Ford’s push into durable, mid-sized construction equipment. Powered by a 3-cylinder diesel engine, the 555B became popular for its simplicity, mechanical reliability, and ease of service. By the early 1980s, Ford had sold tens of thousands of these units across North America, with many still in operation today.
Central to its performance is the fuel injection system, typically equipped with either a CAV DPA rotary pump or a Simms inline pump, depending on production year and regional configuration. These pumps are responsible for metering and delivering fuel to the injectors under high pressure, synchronized with engine timing.
Symptoms of Fuel Dilution and Suspected Pump Failure
One of the more serious issues that can arise in older diesel engines is fuel dilution in the crankcase oil. This condition occurs when diesel fuel leaks into the engine oil, reducing lubrication and potentially causing catastrophic wear. In the Ford 555B, this is often traced to:
- Front seal failure on the injection pump
- Internal leakage within the lift pump or supply pump
- Cracked diaphragm in the fuel pump assembly
- Worn plungers or rotor head in the injection pump
Pump Removal and Timing Precautions
Removing the injection pump from a Ford 555B requires careful attention to timing and access. While some believe the pump can be removed without disturbing the timing gear cover, the reality depends on the pump type:
- CAV DPA pump: Requires access to the drive gear via a front cover plate. The gear is master-doweled, meaning it aligns automatically if not rotated.
- Simms pump: May have an external lift pump bolted to the side, which can be replaced independently.
- Mark the static timing between the pump flange and the engine block
- Scribe alignment marks on the access cover to preserve orientation
- Disconnect the radiator hose for better access if needed
- Avoid rotating the drive gear, which could disrupt timing
Rebuild vs. Replacement Options
When a pump is suspected of internal failure, rebuild is often preferred over replacement—unless the pump is seized or extensively damaged. Rebuilders caution against shops that default to replacement without teardown. A proper rebuild typically costs $650 to $750, while new or aftermarket pumps range from $700 to $1,700, depending on origin and part number.
The pump in question, marked 3238F341, is part of a series where the final digit may vary. Compatibility is based more on application and flange type than exact number. Reputable suppliers can cross-reference pump numbers to confirm fitment.
Aftermarket Sources and Regional Support
Operators seeking affordable replacements have found success with:
- Romanian-built CAV-style pumps, often sold through tractor parts specialists
- Alexander’s Tractor Parts in Texas, known for stocking older Ford diesel components
- Online listings with visual confirmation of flange and port layout
Conclusion
Fuel dilution in the Ford 555B’s diesel engine is a serious issue, often linked to injection pump seal failure. With proper diagnosis, careful removal, and attention to timing, the pump can be rebuilt or replaced without dismantling the entire front end. Operators are advised to seek rebuilders who understand the pump’s internals and avoid unnecessary replacements. With the right approach, even a 1979 model can be restored to dependable service.
