3.3
Section 3
Troubleshooting
3
Basic Engine Tests
Crankcase Vacuum Test
A partial vacuum should be present in the crankcase when the engine is operating at normal temperatures.
Pressure in the crankcase (normally caused by a clogged breather) can cause oil to be forced out at oil seals,
gaskets, or other available spots.
Crankcase vacuum is best measured with water manometer, Kohler Part No. 25 761 02-S, or vacuum/pressure
tester, Kohler Part No. 25 761 22-S. Complete instructions are provided in the kits.
Test the crankcase vacuum, following the instructions, with the engine running at high idle speed (>3500 rpm).
a. The engine should have a minimum of 4" of vacuum. A vacuum less than 4" is usually due to internal wear or
a bad gasket or seal allowing air to leak into the crankcase. A pressure is usually due to a problem with the
breather.
b. Refer to the following chart for possible causes and solutions.
Low/No Crankcase Vacuum or Pressure in Crankcase
Possible Cause
1. Crankcase breather clogged or inoperative.
2. Seals and/or gaskets leaking. Loose or
improperly torqued fasteners.
3. Piston blowby or leaky valves. (Confirm by
inspecting components.)
4. Restricted exhaust.
Solution
1. Disassemble breather, clean parts thoroughly,
reassemble, and recheck pressure.
2. Replace all worn or damaged seals and gaskets.
Make sure all fasteners are tightened securely. Use
appropriate torque values and sequences when
necessary.
3. Recondition piston, rings, cylinder bore, valves, and
valve guides.
4. Repair/replace restricted muffler/exhaust system.
Compression Test
A compression test or a cylinder leakdown test may be
performed to check the condition of an engine.
Insufficient compression pressure will result in a
performance loss and may indicate leaking valves or
damaged/worn piston rings.
Test the compression as follows:
1. Check/perform valve clearance adjustment.
2. Start engine if possible, and run for 3-5 minutes to
warm it up, then stop.
3. Disconnect and ground spark plug lead. Remove
the spark plug.
4. Install adapter and compression tester into spark
plug hole.
5. Move the throttle control to the full/wide open
position. Be sure the choke is off.
6. Crank engine over using recoil or electric starter
and check results.
•
Standard Compression Pressure:
400-600 kPa (57-85 psi) with ACR mechanism
in operation.
Cylinder Leakdown Test
A cylinder leakdown test can be a valuable alternative
to a compression test, especially on engines with ACR.
By pressurizing the combustion chamber from an
external air source you can determine if the valves or
rings are leaking, and how badly.
Содержание COMMAND PRO CS10
Страница 1: ...SERVICE MANUAL COMMAND PRO CS SERIES 4 12 HP HORIZONTAL CRANKSHAFT...
Страница 20: ...1 18 Section 1 Safety and General Information...
Страница 24: ...2 4 Section 2 Special Tools...
Страница 48: ...6 4 Section 6 Lubrication System...
Страница 54: ...7 6 Section 7 Retractable Starter...
Страница 84: ...8 30 Section 8 Electrical System and Components...
Страница 106: ...9 22 Section 9 Disassembly...
Страница 122: ...10 16 Section 10 Internal Components...
Страница 154: ...ENGINE DIVISION KOHLER CO KOHLER WISCONSIN 53044 LITHO IN U S A FORMNO TP 2503 A ISSUED 12 99 REVISED 8 00 MAILED 9 00...