The Groundsmaster 300 series mower is a medium size, maneuverable, commercial rotary with over twenty
years of mowing experience. During those years its design has been continuously improved for optimum
productivity and durability.
GM 345
Features
1. Ford 4 cylinder gas engine (45hp).
2. Sunstrand series M15 inline variable speed hydrostatic drive.
3. Hydraulic power steering and lift functions
4. Available in 2wd.
GM 325-D
Features
1. Mitsubishi 3 cylinder diesel engine (25hp).
2. Sunstrand series M15 inline variable speed hydrostatic drive.
In this section we will look at some troubleshooting procedures for the Ford Gas Engine.
Engine Identification
The engine is identified with a decal affixed to the left side of the valve cover.
The decal contains the engine serial number.
The model number and displacement. ( i.e. 411 = 4 cyl 1.1 liter)
The special options (S.O.) number.
The engine is also stamped on the left rear top edge of the block.
This stamping includes:
A - Serial number.
B - Engine Code.
C - Engine build code: (Example 4K26)
• The first number indicates the year.
• The letter indicates the month in alphabetical sequence. ( A January, B February, etc.)
• The last two numbers are the day of the month.
Complaint: Low engine power
Affect:
5
1. Poor cutting unit performance.
2. Poor hill climbing ability.
3. Slow hydraulic response.
4. Slow throttle response.
5. Rough running engine.
Cause:
1. Incorrect engine idle settings.5. Cracked or bad spark plugs.
2. Misadjusted carburetor linkage.6. Cracked or broken plug wires.
3. Governor adjustments.7. Plugged or restricted air filter.
The final adjustments are made with the engine running. To guard against
possible personal injury, engage the parking brake and keep hands, feet, face
and other parts of the body away from the fan or other moving parts.
Low Idle Adjustment.
1. Start the engine and move the throttle to the slow position.
2. Manually rotate the throttle arm closed until it contacts the stop.
3. Check the idle speed and adjust carburetor idle speed screw, if necessary to attain 1350 ± 50 rpm.
• This prevents the throttle plate from being able to bottom out in the carburetor barrel.
4. Release the throttle arm, loosen the jam nut on the governor low idle speed screw and adjust it to attain
1500 ± 100 rpm.
1. Slowly move the throttle to the FAST position until the engine reaches 3200 ± 100. Shut off the engine.
Adjust the high speed adjustment screw until it contacts the speed control lever.
IMPORTANT: Do not overspeed the engine because transmission damaged could occur.
2. If 3200 rpm can not be attained, check the throttle cable adjustment.
• The governor arm must not contact the cable cover when the unit is at high idle.
• If the governor arm contacts the cable, loosen the retaining bolt and move the cable.
3. If the throttle lever on the instrument panel will not stay in the fast position, remove the panel cover and
tighten the nut and capscrew at the base of the throttle lever.
1. Move the throttle rapidly from SLOW to FAST. The engine should not surge, if the engine surges proceed to
step 2.
2. Check the V-belts from the engine to the governor pulley and assure that they are tight.
• The belt is adjusted to 45 lbs of tension on a belt gauge for a new belt.
• A used belt is re-tensioned to 28 lbs.
• The replacement belt PN is 67-8510.
3. Loosen the jam nut that retains the anti-surge screw. Rotate the screw clockwise 1/8 of a turn at a time until
the surging stops.
4. Check the low and high idle speed to be sure that there is no change in the initial settings. If the idle speed
has increased, the anti-surge screw has been turned in too far and it must be backed out.
Other things to check when engine surges:
A. Carburetor too rich or lean.
B. Binding in the throttle linkage.
C. Governor worn internally.
Governor Spread or Sensitivity Adjustment.
Governor spread is the difference between the no load governed speed, and the full load speed.
For the governor to work correctly this spread should be 5 to 10 percent.
To check governor spread, check and record the no-load high idle speed and compare this to the loaded high
idle speed.
To increase the spread adjust the adjustment bolt to position the spring farther away from the lever hub. To
decrease the spread position the spring closer to the hub.
The cylinder leakage test can locate the following problems:
1. Leaking intake valves.
• Air leaking from carburetor.
2. Leaking exhaust valves.
• Air leaking from muffler.
3. Leaking cylinder head gaskets.
• Air leaking externally by head gasket.
4. Worn piston rings.
• Air leaking from breather or dipstick tube.
NOTE. There will always be some air leakage past the rings. Use the tester gauge to determine the severity of
the leak.
With the engine rotated until the piston is at the top of travel on the compression stroke. The cylinder is filled
with air through the spark plug opening, The leakage tester will display the percentage of air lost when the piston
is at the top part of the compression stroke.
A cylinder leakage of 25 percent or less is acceptable.
Compression Testing.
1. Make sure the batteries are fully charged.
2. Remove all the spark plugs.
3. Set the throttle to high idle and the choke in the wide open position.
4. Install an automotive type (0-300 PSI) compression gauge.
5. Using an auxiliary starting switch, crank the engine (with the ignition switch off) at least five compression
strokes and record the highest reading.
6. Normal compression should read 170 to 185 PSI depending on engine temperature and cranking speed.
7. Repeat the test on each cylinder.
If one or more cylinders read low, and a cylinder leakage tester is not available, squirt approximately one
tablespoon of engine oil on top of the pistons in the low reading cylinders.
Repeat compression test on these cylinders.
1. If the compression improves considerably, the piston rings are at fault.
2. If the compression does not improve, the valves are sticking or seating poorly.
3. If two adjacent cylinders indicate low compression pressures and squirting oil in the pistons does not
increase the compression, the cause may be a leaking cylinder head gasket between the two cylinders.
In this section we will look at some troubleshooting procedures for the Mitsubishi Diesel Engine.
Engine Identification
The engine model number and serial number is listed on a decal on the valve cover.
The engine serial number is also stamped on the injection pump mounting surface.
The exhaust from a diesel engine can provide information about the running condition of the engine. A normally
operating engine will have exhaust that is clear to a slight brownish/gray color.