The D-245.7E3 diesel engine is installed on PAZ-32053-07 buses.
The D-245.9E3 diesel engine is installed on PAZ-4234 and PAZ-32053-07 buses.
The general design of the engine is shown in Fig. 1.
The diesel engines use a Common Rail fuel system with electronic injection control, which ensures environmental performance complying with the Euro-3 level through optimisation of the working process.
The engine comprises:
- cylinder block with suspension;
- crank mechanism and valve timing mechanism;
- lubrication, fuel and cooling systems;
- boost and starting devices, drives of electrical equipment and units.
The crank mechanism consists of: crankshaft, pistons with piston rings and pins, connecting rods, main and connecting rod bearings, flywheel.
The crankshaft is made of steel and has five main journals and four connecting rod journals.
At the front and rear, the crankshaft is sealed by lip seals.
The piston is made of aluminium alloy.
The combustion chamber is formed in the piston crown. In the upper part, the piston has three grooves — compression rings are installed in the first two, and the oil scraper ring in the third.
Under the groove of the upper compression ring, an insert of special cast iron is cast in.
Piston rings. The upper compression ring is made of high-strength cast iron, its cross-section has the shape of an isosceles trapezoid, the second compression ring is conical.
On the end surface at the lock, the compression rings are marked "Верх" ("TOP").
The oil scraper ring is of the box type with a spring expander.
The connecting rod is made of steel.
To lubricate the piston pin, holes are provided in the upper connecting rod head and bush.
The valve timing mechanism consists of the camshaft, intake and exhaust valves, as well as the parts for their installation and drive: tappets, pushrods, rocker arms, adjusting screws with nuts, spring retainers with split keepers, springs, posts and the rocker shaft.
The camshaft is driven from the crankshaft through the timing gears.
Technical characteristics of the diesel engine
| Parameter | Value |
|---|---|
| Engine model | D-245.7E3 or D-245.9E3 |
| Type | Diesel, four-stroke, with turbocharging and charge air cooling |
| Mixture formation method | Direct fuel injection |
| Number and arrangement of cylinders | 4, in-line, vertical |
| Cylinder displacement, l | 4.75 |
| Firing order | 1-3-4-2 |
| Crankshaft rotation direction | right-hand (clockwise) |
| Cylinder bore / piston stroke, mm | D-245.7E3 — 110/125; D-245.9E3 — 110/125 |
| Compression ratio | 17 |
| Rated power, net, kW | D-245.7E3 — 85.0; D-245.9E3 — 95.0 |
| Rated speed, min-1 | 2400 |
| Maximum torque, net, N·m | D-245.7E3 — 422; D-245.9E3 — 456 |
| Speed at maximum torque, min-1 | D-245.7E3 — 1000–1500; D-245.9E3 — 1500–1600 |
| Minimum idling speed, min-1 | 750–800 |
| Maximum idling speed, min-1, not more than | 2650 |
| Crankcase ventilation system | Open |
| Lubrication system | Combined: under pressure from the oil pump and by splashing |
| Cooling in the lubrication system | Liquid-oil heat exchanger |
| Oil filter | Full-flow, non-detachable, mod. FM 009-1012005 or M5101 |
| High-pressure fuel pump | CP3.3 (company "BOSCH", Germany) |
| Diesel electronic control unit | EDC7UC31 (company "BOSCH", Germany) |
| Injector | CRIN2 (company "BOSCH", Germany) |
| Coarse fuel filter | Preline PL 270 (company "MANN-HUMMEL GMBH", Germany) |
| Fine fuel filter | Mann & Hummel WDK962/12 or WDK962/14 (Germany) |
| Air filter | Air cleaner with paper filter elements |
| Boost system | With adjustable boost pressure and air-to-air charge air cooler |
| Turbocharger | C14 (company "Turbo"), C15 (company "Turbo") or S200G (company "Schwitzer", Germany) |
| Diesel cooling system | Liquid, closed type, with forced liquid circulation, thermostat and expansion tank |
| Engine starting aids | Glow plugs and liquid heater |
