Renault S8U engine
Content
The result of the work of a joint group of engineers from well-known automobile companies was the creation of a power unit that won a worthy place among similar internal combustion engines.
Description
The S8U engine (another name is Sofim 8140) was developed and put into production in 1978. Engineers of three automobile concerns - Renault, Fiat and Alfa Romeo - worked on its creation. As a result of joint efforts, a masterpiece of engine building appeared, which did not leave the assembly line almost unchanged until 2006.
The S8U is a 2,5-liter four-cylinder diesel engine with a capacity of 76-115 hp. s at a torque of 155 Nm.
Initially, the engine had a volume of 2445 cm³, a maximum power of 72 liters. s and a torque of 147 Nm. As a result of modernization since 1989, the volume and other performance characteristics have received minor changes (see table 1).
S8U was installed on Renault cars:
- Master (1989-2000);
- Traffic (1990-2000);
- Mtssenger (1989-1996);
- Safrane (1992-1996).
In addition to Renault cars, the engine under the code Sofim 8140 can be found on Opel Movano and Nissan Interstar, Iveco Daily II, Lancia Thema and Fiat Croma.
The engine was created according to the classic diesel scheme. Nevertheless, it contains several interesting technical solutions.
The water pump of the cooling system (pump) is built into the right support of the internal combustion engine.
Timing drive commercial auto belt. Passenger cars have a combined drive, which includes a belt and gears. The auxiliary timing drive unit is driven by a belt, and the gears in it transmit the rotation of the injection pump and a number of pumps - oil, vacuum and power steering.
The peculiarity of the injection pump is that it is a single-plunger (Bosch VE), distribution type. Absolutely not whimsical to the quality of fuel, but very sensitive to moisture getting into it. An all-mode fuel supply regulator is built into the pump.
The fuel system injectors are mechanical, highly reliable and durable.
Thermal valve clearances are regulated by washers.
A few nice words about the lubrication system. It is ideal in terms of undemanding to the quality of the oil. Unfortunately, this does not apply to turbocharged engine modifications.
In general, the S8U engine has a simple design, which has a positive effect on its performance.
Technical specifications
| Manufacturer | Fiat Powertrain Technologies |
| Engine volume, cm³ | 2499 |
| Power, l s | 76-115 |
| Torque, Nm | 155 |
| Compression ratio | 22.5 |
| Number and arrangement of cylinders | 4, in-line |
| Cylinder block | cast iron |
| Cylinder head | aluminum |
| Cylinder diameter, mm | 93 |
| The piston stroke, mm | 92 |
| Number of valves per cylinder | 2 (OHC) |
| Timing drive | belt |
| Hydraulic compensators | no |
| Turbocharging | turbine* |
| Camshaft adjuster | no |
| EGR valve | no |
| Diesel particulate filter | no |
| Fuel system | direct injection |
| Fuel | DT (diesel fuel) |
| Location | transverse/longitudinal** |
*turbines have been installed on the engine since 1985. **depending on the layout of the car model.
What do modifications mean?
Over the years of production, the internal combustion engine has been repeatedly modernized. The main changes concerned the increase in power and torque due to changes in the fuel system and the installation of turbochargers.
The displacement of the engine has also been changed.
| Engine code | Power | Torque | Compression ratio | Years of issue | Installed |
| S8U 750 | 75 l. s at 3900 rpm | 147 Nm | 22 | 1980-2001 | Renault Traffic I, II |
| S8U 752 | 75 l. s at 3900 rpm | 147 Nm | 22 | 1980-2001 | Renault Traffic I |
| S8U 758 | 75 l. s at 3900 rpm | 147 Nm | 22 | 1989-2001 | Renault Traffic I |
| S8U 762 | 113 l. s at 4200 rpm | 240 Nm | 22.5 | 1992-1996 | Renault Safrane I (B54…) |
| S8U 763 | 113 l. s at 4200 rpm | 240 Nm | 22.5 | 1992-1996 | Renault Safrane I (B54E, B548) |
| S8U 770 | 80 l. s at 4000 rpm | 155 Nm | 23 | 1998-2001 | Renault Master II (FD) |
| S8U 772 | 80 l. s at 4000 rpm | 155 Nm | 23 | 1998-2003 | Renault Master II (FD) |
Reliability, weaknesses, maintainability
Reliability
The engine in matters of reliability does not cause any doubts. According to car service workers and car owners, he is rightfully included in the galaxy of millionaires.
This statement is confirmed by Petrovich 36 rus from Svetlograd: “... I have such a motor running on the speedometer for already 700 thousand, and the motor pah, pah, pah is like new ...”. Dr.Diesel from Moscow fully agrees with him: “... such an engine really goes under a million kilometers ...”.
The reliability and survivability of mechanical fuel injectors is noted. The injection pump is also reliable and unpretentious, which is important for our operating conditions.
The S8U is a simple and economical power unit that is not expensive to operate if the manufacturer's recommendations are followed.
Weak spots
The weak points include emerging oil leaks from under the seals of the motor units. Especially a lot of trouble is caused by the laying of the drag plate. It is located under the cylinder block, has two gaskets that dry out over time. To replace them, you have to disassemble the lower part of the engine.
With a stretch, but can be attributed to the weak points of the low service life of the timing belt. It is 80 thousand kilometers (recommended by Renault). The risk of breakage lies in the bending of the valves when they inevitably meet with the pistons.
Certain inconveniences are caused by the need to manually adjust the thermal clearance of the valves due to the lack of hydraulic compensators.
Maintainability
Due to the simple design, the engine is quite maintainable. Craftsmen carry out major repairs of any complexity, even in garage conditions. At the same time, there are some difficulties in carrying out fairly simple operations.
For example, Gruzovoz (Golitsyno, Moscow region) writes: “... To replace the middle gasket, the motor does not need to be removed if it is possible to work under the machine. True, there is a lot to do. It is necessary to remove the box, flywheel, rear KV oil seal, and also remove everything in front - KV pulley, timing belt, KV front oil seal, engine pan, and only then the lower part of the block ". (We are talking about replacing the gaskets of the drag plate).
Along with restoration work, it is worth considering the option of acquiring a contract engine. The solution to this issue is not a problem - many online stores offer an engine in various configurations.
The S8U power unit, subject to the manufacturer's recommendations, is able to work out a very long resource without serious breakdowns and delight the car owner for many years.
