Stihl MS 251 Instruction Manual - Page 35
Vacuum Test, 6.2.3 Pressure Test, pressure remains constant for
View all Stihl MS 251 manuals
Add to My Manuals
Save this manual to your list of manuals |
Page 35 highlights
2 2 1 : Line up the flange (1) 1118 850 4200 and fit it over the studs : Fit the test flange (1) 1118 850 4200. : Fit the nuts (2) and tighten them down firmly. 6.2.2 Vacuum Test Oil seals tend to fail when subjected to a vacuum, i.e. the sealing lip lifts away from the crankshaft during the piston's induction stroke because there is no internal counterpressure. A test can be carried out with pump 0000 850 1300 to detect this kind of fault. 2310RA075 TG : Push ring (2) to the left - vacuum test. : Operate the lever (3) until the pressure gauge (4) indicates a vacuum of 0.5 bar. If the vacuum reading remains constant, or rises to no more than 0.3 bar within 20 seconds, it can be assumed that the oil seals are in good condition. If the pressure continues to rise (reduced vacuum in the engine), the oil seals must be replaced, b 6.3. - After finishing the test, push the ring to the right to vent the pump. - Continue with pressure test, b 6.2.3 6.2.3 Pressure Test Carry out the same preparations as for the vacuum test, b 6.2.2 3 2 - If the pressure drops, the leak must be located and the faulty part replaced. To find the leak, coat the suspect area with soapy water and pressurize the engine again. Bubbles will appear if a leak exists. - After finishing the test, push the ring to the left to vent the pump - disconnect the hose. - Remove the flange 1118 850 4200 from the intake manifold. - Install the carburetor, b 12.5 - Remove the flange 5910 855 4201 and sealing plate 0000 855 8106. - Install the muffler, b 6.1 - Use a blunt tool to push home the new plugs - take care not to damage the plugs. - Reassemble all other parts in the reverse sequence. 4 3 1 2 : Connect hose (1) of pump 0000 850 1300 to the nipple (arrow). 2310RA076 TG 2310RA077 TG 1 : Push ring (1) to the right - pressure test. : Operate the lever (2) until the pressure gauge (3) indicates a pressure of 0.5 bar. If this pressure remains constant for at least 20 seconds, the engine is airtight. 34 MS 231, MS 231 C, MS 251, MS 251 C