Guardian Technologies 4582 & 4987 Manual De Usuario

Page 59

CROW'S FOOT

INSTALL ROCKER ARM COVER
1. Use  a  new  rocker  arm  cover  gasket.  Install  the  rocker  arm

cover and retain with four screws.

RESULTS:
Adjust  valves  to  specification  and  retest.  If  problem 

continues, refer to Flow Chart.

Most engine problems may be classified as one or a 

combination of the following:
•  Will not start.
•  Starts hard.
•  Lack of power.
•  Runs rough.
•  Vibration.
•  Overheating.
•  High oil consumption.
The  Cylinder  Leak  Down  Tester  (Generac  P/N 

0F77000SRV) checks the sealing (compression) abil-

ity  of  the  engine  by  measuring  air  leakage  from  the 

combustion  chamber.  Compression  loss  can  present 

many  different  symptoms. This  test  is  designed  to 

detect  the  section  of  the  engine  where  the  fault  lies 

before disassembling the engine.

PROCEDURE:
1. Remove a spark plug.

2. Gain access to the flywheel. Remove the valve cover.

3. Rotate the engine crankshaft until the piston reaches top dead

center (TDC). Both valves should be closed.

4. Lock the flywheel at top dead center.

5. Attach cylinder leak down tester adapter to spark plug hole.

6. Connect an air source of at least 90 psi to the leak down tester.

7. Adjust the regulated pressure on the gauge to 80 psi.

8. Read the right hand gauge on the tester for cylinder pressure. 20

percent  leakage  is  normally  acceptable.  Use  good  judgement,
and listen for air escaping at the carburetor, the exhaust, and the
crankcase breather. This will determine where the fault lies.

9. Repeat Steps 1 through 8 on remaining cylinder.

RESULTS:
•  Air escapes at the carburetor – check intake valve.
•  Air  escapes  through  the  exhaust  –  check  exhaust 

valve.

•  Air  escapes  through  the  breather  –  check  piston 

rings.

•  Air escapes from the cylinder head – the head gas-

ket should be replaced.

CHECK COMPRESSION:
Lost or reduced engine compression can result in (a) 

failure  of  the  engine  to  start,  or  (b)  rough  operation. 

One or more of the following will usually cause loss of 

compression:
•  Blown or leaking cylinder head gasket.
•  Improperly seated or sticking-valves.
•  Worn Piston rings or cylinder. (This will also result in 

high oil consumption).

PROCEDURE:
1. Remove both spark plugs.

2. Insert a compression gauge into either cylinder.

3. Crank the engine until there is no further increase in pressure.

4. Record the highest reading obtained.

5. Repeat the procedure for the remaining cylinder and record the

highest reading.

RESULTS:
Normal compression is approximately 150 psi. The dif-

ference in pressure between the two cylinders should 

not exceed 25 percent. If the difference is greater than 

25 percent, loss of compression in the lowest reading 

cylinder is indicated.
Example  1:  If  the  pressure  reading  of  cylinder  #1  is 

No. 2 cylinder is indicated.
If compression is poor, look for one or more of the fol-

lowing causes: