BOMBARDIER ski-doo Tundra Scandic 2004 Series, Shop Manual, Page: 67 / 427

Section 03 TROUBLESHOOTING
Subsection 02 (ENGINE)
MMR2004-106_03_02A.FM
03-02-3
4. Melted and/or perforated piston dome; melted section at ring end gap.
a. When piston reaches TDC, mixture is ignited by heated areas in combustion chamber.
This is due to an incomplete combustion of a poor quality oil.
Clean residue accumulation in combustion chamber and replace piston(s).
Use BOMBARDIER injection oil.
b. Spark plug heat range is too high.
Install recommended dry properly gapped spark plugs (refer to TECHNICAL DATA).
c. Ignition timing is too advanced.
Adjust according to specifications (refer to TECHNICAL DATA).
d. Inadequate fuel quality.
Use appropriate fuel.
e. Carburetion is too lean.
Adjust according to specifications (refer to TECHNICAL DATA).
5. Seized piston all around the circumference (dry surface).
a. Lack of oil, damaged oil line or defective injection pump.
Replace defective part(s).
6. Grooves on intake side of piston only.
a. Oil film eliminated by water (snow infiltration in engine). This can also be caused
by running engine on choke for too long. Excessive fuel will remove the oil film on
the piston and make marks.
Replace piston(s) and check if intake system leaks.
7. Piston color is dark due to seizure on intake and exhaust sides.
a. Broken or loose fan belt.
Replace fan belt and/or adjust its tension (refer to TECHNICAL DATA).
b. Cooling system leaks and lowers coolant level.
Proceed with a leakage test (refer to LIQUID COOLING SYSTEM) and repair as
required. Add coolant in cooling system until appropriate level is reached.
c. Accumulation of foreign particles in needle valve and/or main jet area.
Clean carburetor(s).
8. Cracked or broken piston(s).
a. Cracked or broken piston(s) due to excessive piston/cylinder clearance or engine
overreving.
Replace piston(s). Check piston/cylinder clearance (refer to TECHNICAL DATA).
Adjust drive pulley according to specifications (refer to TECHNICAL DATA)
and/or clean pulley sheaves if they are contaminated with greasy particles.
9. DPM manifold air vent is obstructed.
a. Carburetion is too lean.
Ensure proper air vent.
SYMPTOM ENGINE SUDDENLY TURNS OFF.
CONDITION NORMAL USE.