Yanmar YM276 Service Manual page 605

TROUBLE SHOOTING
THE POWER TRAIN
250-50.1
GENERAL INFORMATION
-
PRELIMINARY CHECKS AND ADJUSTMENTS
Prior t o attempting t o specifically diagnosis any
power train problem, the following checks and
adjustments should be performed t o help isolate the
problem.
1.
Ask the operator about all complaints or symptoms.
Be sure the operator is using the tractor properly.
2. Check the transmission oil.
a) If oil level i s low, check for leakage a s instructed
on page 250-50-2.
Replenish after the repair i s
made.
b ) If oil level is high, check t o see i t high oil level has
caused seal leakage and repair as necessary. Drain
oil t o the proper level.
c) If oil is contaminated, drain oil a n d remove the
filter screen. Check for parts fragments that may
indicate damage t o gears or bearings.
Remove
transmission covers t o visually determine area of
damage. Separate and rwair as necessary and
replenish with clean oil.
A
d l If oil appears t o have overheated, be foamy or
discolored, see Chapter 270 to determine main
hydraulic system problem. Be sure proper type of
oil has been applied. After problem has been
corrected, clean filter screen and replenish with
clean oil.
3. Visually inspect the tractor.
a) Note any leakage due t o damaged housings or
covers, leaking gaskets or seals.
Repair as neces-
sary.
b) Check all linkage and operating levers and pedals
for damage or binding.
4. Check clutch pedal free play. If incorrect, adjust t o
15 t o 25 mm (0.591 t o 1 in.).
ISOLATING THE PROBLEM TO CLUTCH
HOUSING, TRANSMISSION, PTO, FINAL
DRIVE OR FRONT WHEEL DRlVE
The following procedure assumes noise accompanies
a drive malfunction. I f noise is minimum but a power
transmission problem exists, use of a mechanic's
stethoscope may help. Otherwise use the procedure
noting a l l operating characteristics t o systematically
trace the mulfunction.
Noise Isolation
1. All shift levers in Neutral position
a) Place the power shift, range, PTO, and front wheel
drive shift levers in their neutral positions. Also,
be sure t h e differential lock pedal is in i t s dis-
engaged positions.
b) Engage the engine clutch and vary engine speed
from 800 t o 2600 rpm.
C )
I f the noise or vibration occurs, lock for a prob-
lem
-
.
In the flywheel or clutch housing?
In the main shaft bearings?
r
I n the clutch gear bearings?
r
In the PTO drive and pinion shafts bearings?
r
Power shift pump?
I n the power shift pump bearings?
r
I n the counter shaft bearings?
Main gears and clutch gears broken?
2.
Power shift lever i s in each position, but other levers
in neutral positions.
a) Engage the engine clutch and vary engine speed
from 800 t o 2600 rpm.
b) If the noise or vibration occurs, look for a problem
In the flywheel or clutch housing?
.
In the main shaft bearings?
In the
PTO
drive and pinion shafts bearings?
Power shift pump?
In the power shift pump bearings?
In thecounter shaft bearings?
Main gears and clutch gears broken?
.
Clutch shah bearings and needle bearings
broken?
.
Counter shaft gear and counter gears broken?