20/07/2019
Understanding CAV Injection Pumps
The CAV (C.A.V. - later Lucas CAV) injection pump is a cornerstone of diesel engine technology, particularly prevalent in classic agricultural machinery, older commercial vehicles, and some classic cars. These robust and reliable pumps, while celebrated for their durability, often require specialized knowledge for maintenance, repair, and performance tuning. If you're a proud owner of a vehicle or piece of equipment powered by a CAV injection pump, understanding where to find essential parts and how to perform basic adjustments can save you considerable time and expense. This guide will delve into sourcing components and provide a practical, albeit cautionary, look at adjusting fuel delivery on these iconic pumps.
Where to Find CAV Injection Pump Parts
Locating genuine or high-quality aftermarket parts for older systems like the CAV injection pump can sometimes feel like a treasure hunt. However, with the right resources, it's entirely achievable. The most direct and often recommended source for CAV injection pump parts is specialist suppliers who focus on classic diesel components. One such reputable supplier is Waltstractors.com. They have established themselves as a reliable destination for a wide range of tractor parts, including those specifically for CAV injection systems. Whether you need seals, gaskets, plungers, delivery valves, or even complete pump components, checking with specialists like Waltstractors.com is your first port of call.
When searching for parts, it's crucial to have your pump's specific model number readily available. CAV pumps came in various configurations, and using the correct part number ensures compatibility. You can usually find this information stamped directly onto the pump's body. Don't hesitate to contact the supplier directly if you're unsure about a specific part; their expertise can be invaluable in identifying the correct component for your needs.
Commonly Replaced CAV Pump Components:
| Component | Typical Reason for Replacement | Importance |
|---|---|---|
| Seals and Gaskets | Age-related degradation, leaks | Prevent fuel leaks and contamination |
| Delivery Valves | Wear, sticking | Control fuel injection timing and pressure |
| Plunger and Barrel Assemblies | Wear, scoring | The heart of the pump, responsible for metering and pressurising fuel |
| Diaphragms | Perishing, tearing | Control pressure and fuel flow regulation |
| Filters | Clogging | Protect internal pump components from debris |
Tuning Your CAV Injector Pump: Increasing Fuel Delivery
For those looking to extract a bit more performance from their diesel engine, adjusting the fuel delivery on a CAV pump is a common modification. However, it is essential to approach this task with extreme caution and a thorough understanding of the implications. Incorrect adjustments can lead to engine damage, increased smoke, overheating, and reduced fuel efficiency. If you are not confident in your mechanical abilities, it is strongly recommended to seek the assistance of a qualified diesel mechanic.
The process involves adjusting the 'fuel plate' or 'regulator plate' within the pump. This plate influences the maximum fuel output by controlling the stroke of the plungers. Here's a breakdown of the procedure, as described:
Step-by-Step Fuel Adjustment Guide:
- Locate the Fuel Plate: On the side of the CAV injection pump, you will find a plate, often secured by a few bolts. This is the fuel plate you need to access.
- Prepare for Fuel Leakage: Upon removing this plate, be aware that fuel will likely drain from the pump. Have a suitable container ready to catch the spilled diesel and minimise mess.
- Identify the Adjustment Mechanism: Once the plate is removed, you'll see a steel wheel with letters or markings on it, mounted on a shaft. This wheel is connected to the governor mechanism. Two bolts pass through this wheel and thread into an underlying plate. These bolts control the position of the fuel plate.
- Loosen the Bolts: Using an 8mm wrench (or the appropriate size), carefully loosen these two bolts. They may be tight, but they should not require excessive force.
- Crucial Warning: DO NOT SLIDE THE WHEEL OFF THE SPLINE SHAFT. This is a critical point. The splined shaft allows for precise positioning of the wheel. Attempting to remove the wheel from the splines can make reassembly incredibly difficult and potentially damage the components.
- Making the Adjustment: The underlying plate, into which the bolts thread, is what you need to rotate. To increase fuel delivery, you will turn this plate towards you by one full turn. It's important to make full turns to ensure the bolts can be properly re-threaded. Turning the plate the opposite way (away from you) will decrease fuel delivery.
- Reassembly: Carefully re-insert the bolts through the steel wheel and into the adjusted plate. Tighten them securely. Re-attach the side plate of the pump, ensuring all seals are in good condition.
- Bleeding the Fuel System: After any work on the injection pump, it is imperative to bleed the air from the fuel system. This typically involves loosening the fuel lines at the injectors and cranking the engine until fuel emerges without air bubbles, then retightening them. Refer to your vehicle's manual or a reliable service guide for the specific bleeding procedure for your model.
Important Considerations for Tuning:
- Smoke: Increasing fuel delivery too much will result in excessive black smoke, indicating incomplete combustion.
- EGTs (Exhaust Gas Temperatures): Higher fuel rates mean higher combustion temperatures. Monitor your EGTs closely, as excessive heat can quickly damage your engine, particularly the turbocharger and pistons.
- Driveability: While more fuel can mean more power, it can also make the engine less responsive or 'lumpy' if not adjusted correctly.
- Fuel Economy: Expect a reduction in fuel economy when increasing fuel delivery.
- Legality: Be aware of emissions regulations in your region. Tampering with fuel systems can render your vehicle illegal for road use.
Troubleshooting Common CAV Pump Issues
CAV pumps, like any mechanical component, can develop faults over time. Here are a few common issues and potential causes:
Symptomatic Problems and Solutions:
| Symptom | Potential Cause(s) | Possible Solution(s) |
|---|---|---|
| Hard Starting / No Start | Air in fuel system, clogged filter, faulty lift pump, worn pump internals | Bleed system, replace filter, check lift pump, professional pump overhaul |
| Rough Idling | Air in system, uneven injector spray, worn pump components | Bleed system, service injectors, pump inspection |
| Lack of Power | Fuel plate adjustment too low, clogged filter, weak lift pump, internal pump wear | Adjust fuel plate, replace filter, check lift pump, pump overhaul |
| Excessive Smoke | Over-fuelling, incorrect injection timing, worn injectors, air filter restriction | Reduce fuel delivery, check timing, service injectors, replace air filter |
| Fuel Leaks | Worn seals or gaskets, loose fittings | Replace seals/gaskets, tighten fittings |
Frequently Asked Questions (FAQ)
Q1: Can I adjust the fuel on my CAV pump myself?
Yes, it is possible, but it requires care and attention to detail. If you are unsure, it's best to consult a professional. Incorrect adjustments can lead to engine damage.
Q2: Where can I find specific parts for my CAV pump model?
Specialist suppliers like Waltstractors.com are excellent resources. Always have your pump's model number ready when searching for parts.
Q3: What happens if I turn the fuel plate the wrong way?
Turning the plate away from you will decrease the fuel delivery, resulting in less power. Turning it too far or incorrectly can affect the governor's operation.
Q4: Do I need to bleed the system after adjusting the fuel plate?
Yes, it is highly recommended. Any time the fuel system is opened or disturbed, air can enter, and bleeding ensures proper fuel delivery to the injectors.
Q5: How much extra fuel can I safely add?
This varies greatly depending on the engine, its condition, and cooling system. A small, incremental increase is advisable, coupled with monitoring exhaust gas temperatures and engine performance.
In conclusion, maintaining and tuning a CAV injection pump requires a blend of diligence and knowledge. By sourcing your parts from reputable suppliers and approaching adjustments with a methodical and cautious mindset, you can ensure your classic diesel engine continues to perform reliably for years to come.
If you want to read more articles similar to CAV Injection Pump Parts & Tuning, you can visit the Automotive category.