Valve Assembly Cone Bore Seal Tester Kit – Quantitative Leak Detection For Bosch 110/120 & Fukang Series

In common rail systems, the conical seat between the valve assembly and the injector body is the ultimate barrier against high‑pressure fuel bleed‑off. Even a microscopic imperfection – a scratch depth of just 5 microns or an angular deviation of 0.02° – can cause a pressure drop of over 100 bar during the dwell phase, directly compromising injection timing and quantity. Traditional leak tests rely on visual inspection or bubble testing, both subjective and insensitive. Our Valve Assembly Cone Bore Seal Tester Kit introduces a quantitative leakage fingerprinting methodology that measures the pressure decay rate over a precisely controlled time window, converting it into a standardised leakage value (mL/min). This approach not only detects the presence of a leak but also grades its severity, allowing technicians to distinguish between acceptable wear and catastrophic failure. The kit is purpose‑calibrated for Bosch 110 and 120 series valve assemblies (used in many European and Asian common‑rail injectors) as well as the Fukang (Foton Cummins) series, which employ a similar cone geometry but with slightly different seat angles.

Our tester operates on two complementary principles to cover all service scenarios. The primary mode is positive pressure hold: the fixture seals the valve assembly's inlet port and applies a regulated air pressure of 6.0 bar (adjustable up to 10 bar) to the cone seat. An integrated precision pressure transducer (accuracy ±0.05% FS) records the pressure at 100 ms intervals over a 30‑second stabilisation phase, followed by a 60‑second measurement phase. The onboard microprocessor calculates the rate of pressure decline and displays it as a leakage flow rate. For sensitive assemblies where even positive pressure might disturb O‑ring seals, the secondary vacuum decay mode pulls a negative pressure of ‑0.8 bar and monitors the rise rate – an effective method for detecting micro‑cracks in the cone surface that only open under suction.

The critical differentiator among these valve families is the cone angle and the sealing land diameter. Bosch 110 and 120 series share a 60° included cone angle with a 6.0 mm sealing diameter, while the Fukang series uses a 58° angle with a 6.5 mm diameter – a seemingly small difference that makes universal fixtures leak‑prone. Our kit includes three interchangeable test heads: one for Bosch 110 (marked in blue), one for Bosch 120 (green), and one for Fukang (red). Each head is CNC‑machined from hardened stainless steel with a matching cone counter‑surface, lapped to a surface finish of Ra 0.2 µm. The heads mount onto the main body via a bayonet lock, enabling tool‑less change‑over in under 10 seconds. The fixture also incorporates a floating centring pin that automatically aligns the valve's pilot diameter, ensuring repeatable seating even with worn components.

Leakage rates are notoriously temperature‑sensitive – a 10°C rise can increase the measured leak by up to 15% due to air viscosity changes. Our tester includes a thermistor probe that monitors the fixture temperature and an ambient air sensor. The internal algorithm applies a real‑time correction factor, normalising all readings to a reference temperature of 20°C. This feature is indispensable in workshops where the test bench may sit near an open door or an engine dyno cell. The correction factor is displayed on the screen, and the raw and compensated values are both stored in the internal memory (capacity for 200 test logs).

The 3.5‑inch colour display shows a real‑time pressure decay curve, allowing the technician to visualise the leak behaviour. A green/red indicator instantly flags whether the assembly passes the preset threshold – by default set at 0.5 mL/min for Bosch and 0.8 mL/min for Fukang (based on OEM specifications), but fully user‑adjustable. The device also calculates the standard deviation of the pressure readings during the measurement phase, providing a confidence metric. If the deviation exceeds 5% of the average, the tester prompts the user to re‑seat the valve, as inconsistent readings often indicate improper fixture alignment or debris contamination.

Q1: How do I know whether the detected leak comes from the cone seat itself or from the O‑ring seals around the valve body?
Our tester includes a blanking plug that isolates the O‑ring seals from the test circuit. You first test the valve with the plug installed – any leakage then indicates a cone seat fault. Removing the plug allows the full assembly test; the difference between the two readings gives the O‑ring contribution. This diagnostic step is included in the quick‑start guide.

Q2: The 110 and 120 series look very similar – can I use the same test head for both?
No. The Bosch 110 and 120 have a 0.2 mm difference in the pilot diameter, which affects the centring. Using the wrong head will produce false high leakage readings. The heads are clearly colour‑coded and engraved with the part number. We also provide a compatibility chart in the case lid.

Q3: Does the tester require a dedicated compressed air supply, or can I use a standard shop air line?
You can connect the tester to any dry, filtered shop air line (regulator built‑in) or use the supplied hand pump for field applications. The internal pressure regulator ensures a stable test pressure even if the shop supply fluctuates between 6 and 10 bar.

Q4: How often should I calibrate the tester, and is the calibration process complicated?
We recommend a calibration check every 6 months using the included reference leak orifice. The procedure involves connecting the orifice and running the test – if the reading deviates by more than 2%, you can perform an automatic zero‑span calibration via the on‑screen menu, guided by step‑by‑step instructions.

Q5: Can this tester be used for valve assemblies removed from other engine brands, such as Delphi or Siemens?
The kit is optimised for Bosch 110/120 and Fukang geometries. For Delphi or Siemens, the cone angles and sealing lands differ, but we offer custom test heads upon request with the required engineering drawings. Contact our support team for a consultation.

Q6: What is the typical test time per valve, and how does it compare to a bench injector tester?
A complete test (including fixture mounting and two measurement modes) takes about 3 minutes per valve. This is significantly faster than a full injector test bench, which often requires 15 minutes per injector. Our tester focuses exclusively on the cone seal – the most common failure point – giving you a rapid screening tool before investing in a full rebuild.

 

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