Test compression pressure - AR01.00-P-1200MCU

2012 Smart Fortwo Electric Drive, 2D CoupeSECTION Test compression pressure - AR01.00-P-1200MCU

ENGINE 132.910 in MODEL 451.3/4 

Fig 1: Testing Compression Pressure
G10977982Courtesy of MERCEDES-BENZ USA
DANGER Risk of accident  from vehicle starting off by itself when engine running. Risk of injury  (bruises and burns) resulting from working on the engine while it is being started or when it is running. Secure vehicle to prevent it from starting off by itself. Wear closed and snug-fitting work clothes. Do not touch hot or rotating parts. AS00.00-Z-0005-01A
REMOVINGINSTALLING Remove/install     
1 Bring engine up to operating temperature of approx. 80°C IMPORTANT Only check compression pressure for an engine is at operating temperature.  
2 Switch off ignition    
3 Remove spark plugs    
REFER TO MAINTENANCE     AP15.10-P-1580MCC
INSPECT Check     
4 Route electrical line (2) for compression recorder (1) between air filter housing (3) and throttle valve actuator (M16/6) to the starter (M1) SPECIAL TOOL Compression tester Fig 2
DANGER Risk of death  caused by vehicle slipping or toppling off of the lifting platform. Align vehicle between vehicle lift columns and position the four support plates at the vehicle lift support points specified by the vehicle manufacturer. AS00.00-Z-0010-01A
5 Raise vehicle with vehicle lift    
6 Detach connector (4) from starter (M1)    
7 Attach terminals (5, 6) of compression recorder (1) to the starter (M1)    
8 Lower vehicle with vehicle lift    
9 Turn engine using contact switch on compression recorder (1) for about 5 seconds IMPORTANT In order to remove combustion residues from the cylinders.  
10 Insert compression recorder (1) with appropriate connector into spark plug bore    
11 Crank engine with contact switch at the compression recorder (1) until an increase in pressure is no longer indicated on the compression recorder (1)    
12 Carry out test procedure at remaining cylinders in the same way    
13 Compare measurements obtained with the permissible values Compression pressure new value *BE01.00-P-1001-01G 
Compression pressure: wear limit or limit value If the wear limit is not reached, cylinder leakage must be checked on the respective cylinder: *BE01.00-P-1002-01G 

Check cylinders for leaks
AR01.00-P-1300MCU 
14 Install in the reverse order    
15 Read out fault memory using the diagnostic system and delete    
REFER TO SELF-DIAGNOSTIC SYSTEMS     AD00.00-P-2000-04MCC
CHECK VALUES FOR COMPRESSION PRESSURE

Number Designation ENGINE 132.910
BE01.00-P-1001-01G Compression pressure new value bar 15
CHECK VALUES FOR COMPRESSION PRESSURE

Number Designation ENGINE 132.910
BE01.00-P-1002-01G Compression pressure: wear limit or limit value bar ≈ 11
Fig 2: Identifying Compression Tester (001 589 76 21 00)
G10977983Courtesy of MERCEDES-BENZ USA
RENDER: 1.0x

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When to See a Mechanic

Stop DIY work and contact a certified mechanic immediately if any of the following apply:

  • You smell fuel, burning insulation, or see smoke.
  • Brakes feel soft, pull hard to one side, or make grinding noises.
  • The engine overheats, stalls repeatedly, or misfires under load.
  • You are missing required tools, torque specs, or safe lifting equipment.
  • You are not confident in the next step or safety outcome.