INDUSTRIAL CASE STUDY|HEAVY MACHINE BUILDING|ROAD TRANSPORT · ENGINE
TECHNICAL REPORT OF THE MOTOR TRANSPORT SHOP, PJSC NKMZ
ZiL-131 engine: cylinders evened out in compression, no teardown
PRODUCTXADO 1 STAGE revitalizant gel27.0 ml tube · lubrication system prepared with XADO Vitaflush cleaner
TEST OBJECTZiL-131 truck, reg. no. AN 9719 VSgasoline eight-cylinder engine · cylinder-piston and crank-and-rod assemblies
DOCUMENT TYPETechnical report
Motor Transport Shop, PJSC NKMZsigned by the commission, certified with the shop seal
Motor Transport Shop, PJSC NKMZsigned by the commission, certified with the shop seal
Key result
compression evened out across the cylinders
↑0.2bar
compression in the weakest cylinder, 8.0 → 8.2 bar; the other cylinders changed within 0.5 bar
| MACHINE | MILEAGE AT START OF TESTING | WHAT WAS MEASURED |
|---|---|---|
| ZiL-131, reg. no. AN 9719 VS, in service since 1986 | 73 237 km | Compression in all eight cylinders — before treatment and after 3420 km of running |
Engine compression by cylinder — before treatment and after 3420 km of running
| CYLINDER | BEFORE TREATMENT, bar | AFTER 3420 KM, bar | CHANGE, bar |
|---|---|---|---|
| I | 8.0 | 8.2 | +0.2 |
| II | 8.5 | 8.3 | −0.2 |
| III | 8.7 | 8.5 | −0.2 |
| IV | 8.2 | 8.2 | 0 |
| V | 8.7 | 8.5 | −0.2 |
| VI | 9.0 | 8.5 | −0.5 |
| VII | 8.5 | 8.5 | 0 |
| VIII | 8.8 | 8.5 | −0.3 |
| Range across the engine | 8.0–9.0 | 8.2–8.5 | lower bound +0.2, upper bound −0.5 |
ZECA 362 compression tester, engine temperature 50 °C at both measurements; the measurement cards are attached to the report. The report states the cylinder-to-cylinder spread in kgf/cm².
Conclusions of the report
The technical report of the motor transport shop of PJSC NKMZ recorded the following: the initial measurements established that compression in the engine ranged from 8.0 to 9.0 bar — a normal value for engines of this model given the design compression ratio of 6.5 — but the maximum cylinder-to-cylinder compression spread was 1 kgf/cm², "which for a gasoline engine is the maximum permissible value". After the vehicle had covered 3420 km, repeat measurements were taken: compression ranged from 8.2 to 8.5 bar and the maximum cylinder-to-cylinder spread was 0.3 kgf/cm², "which is comparable to the compression spread of new engines". The report explains the decrease in individual cylinders by the fact that the initial value there was higher owing to the oil wedge in the thermal clearances enlarged by wear. Conclusion: "after the treatment the mechanical wear has been localized, the thermal clearances have been optimized, and the compression across the cylinders has likewise become optimal".
The results relate to the gasoline engine of a ZiL-131 truck under the operating conditions of the motor transport shop of PJSC NKMZ; on other machinery and under different conditions the figures may differ. The original technical report bearing signatures and seal is published in full and available for download.
Current equivalent
- Revitalizant gel for cylinder restorationEngine cylinders, deep wear
- Revitalizant gel for petrol enginesPetrol engines
How such units are treated: