My mother has an old 11.5 HP Cox Stockman. Just today, the main drive belt has become coming off, (3 times in a row so far) Please advise possible problem and solution. Thanks.

well 21 years old and no engine told at all, zero clues ,hard case that.
running 21 year old spark plugs and thermostat? and at 21 year old cam drive belt ? oops1,23,
oops.
what engine is it 1 or 3? we can not guess engines.
USA spec list , no country told.

1. 3.4 L 5VZ-FE V6 190 hp (2000-2004)yes
2. 4.0 L 1GR-FE V6 236 hp (2005-2006) NO and is CHAIN.
3. 4.7 L 2UZ-FE V8 yes and is interference n.

engine 1 and 3 are belt drive cams
the belt lasts for 60 to 90k miles, depends on belt maker quality.
if belt slips all cylinders drop compression HUGE and will misfire all
below 150psi per cyl. fails.
now the ASE macro list

1. engine bad. cam belt slipped.(sure it did ignored for ever)
2. bad spark, top cause 21 year old spark plugs and wire sets
3. weak fueling called lean misfire. injectors partly clogged or low fuel pressure FPR BAD this sold.

we do not know any cars service history here that be ESP wild.
and matters most (a fact)
21 year old parts love to fail.( a short list)
spark parts.(plugs and HV wires sets (no not mix up wires)
filters (both are tune up parts)spark filters
thermostat bad., not one lasted this long, eva.
battery main bad, (not this time)
alternator dead. cause battery *****.too.
bad fuel, parked for years idle.
bad belts, cam for sure most not be allowed to faill
bad cam belt on 4.7L bend head valves over. interference engine.

this is the short list.
scan of ECT and LTFT and 02 sensors
and scan PENDING DTC

When did you last change the timing belt? If the belt slipped a tooth it could cause your issue. I would do a compression test of all cylinders to see if they are good. Any major variation would indicate a possible timing belt slip. Be advised that this is an interference engine and if the belts breaks or slips too far, valve or piston damage can occur.

Michelle. There are several install procedures that vary by vehicle. Different manufactures use different setups some only require releasing tension on the belt tensioner with a 1/2" drive ratchet or breaker bar or most any type pry bar to replace a belt. That set up is usually only on vehicles with a serpentine belt, the big wide flat type of belt that drive most the engine components. Other manufactures may require you to loosen the belt with a wrench of some type via a pulley mounting bolt and then set the tension by wrench adjustment of another bolt that the mounting bolt locks in place. Most of the time its not really a fix to just reattach a jumped belt. Before you go much further you need to first determine why the belt came off. This is not a normal occurrence. There are several possibilities such as: The belt is worn out . . . when a belt wears out it often has reinforcement fibers in it that break causing it to twist and try to run sideways under pressure. This usually results in the belt overheating and/or coming off the pulleys. Reinstalling a belt that behaves this way is a waste of time because it will just come off again. If the belt is more than 3 to 5 years old go ahead and replace it with a new one. The second question is: If the belt is fairly new or only a few years old why did it come off? A likely possibility is that the belt tensioner is worn out and not able to keep the recommended pressure on the belt and/or is twisting out of line with the other pulleys. Either way the tensioner should be replaced with a new one. The third possibility is that one of the components that the belt drives has become misaligned or has a bearing problem cause misalignment and/or overheating of the belt pulley attached to it. Check all components for bearing wear. The pulleys on them should turn smoothy with out sideways play or any roughness. If this is a power steering belt have the suspension and steering component inspected for worn out components causing excessive resistance causing the power steering pump to become overloaded and prematurely wearing out the belt. Just one example is then the vehicle makes popping noised when actually turning the steering wheel usually heard at low speeds but the noise stops when you hold the wheel still even while continuing to drive the vehicle around in a circle. This is often from a failed strut bearing located at the top of a suspension strut or possible from a, or several, under lubricated or failing ball joints.

no year stated.. now that , is a challenge, no?
front wipers
see those, wiper arms, see them connect to the bottom nut there
and that nut passes to the motor linkage and to the MOTOR.
see those boxes in the upper window, frame, might take a peak there.


the 1979 suzuki SJ20 stockman , in Australia? looks like a jeep?
that stockman.?\
like this.?
http://upload.wikimedia.org/wikipedia/commons/thumb/d/dc/Suzuki_Jimny_SJ10_001.jpg/800px-Suzuki_Jimny_SJ10_001.jpg

in later years, the Motor is in the COWL.
but no year, no joy here.

remove timing belt and move crank shaft and cam shaft tiltiming marks are in the rigt places, put belt back on making sure not to move either pulley, being that far out of time should not cause any internal damages, but will prevent vehicle from starting.

Possible that the steering servo is not activating, check the drive to see if the assistance has stopped - if electrical motor assist or if the belt is loose on the hydraulics pump in the main drive.
Does any indication come up on the dash board- as warning light.

If you are keeping the car, yes. Belt is made of rubber. Rubber is 11 years old. I wouldn't drive it far before changing it...

It might be time to move to 10W30 oil in your 11 year old vehicle. Do you change your own oil? Try 3 qts 5W30 and 2 qts 10W30 of what you normally use.

Recommended by kia is 100,000 km.

Timing Belt: Service and Repair
TIMING BELT
COMPONENT
REMOVAL
1. Disconnect negative battery cable.
2. Loosen power steering lock bolts and nuts accordingly and remove tension from Power Steering (P/S) and/or Air Conditioning (A/C) compressor
drive belt.
3. Remove P/S and/or A/C drive belt.
4. Loosen generator mounting bolts and adjusting bolt.
5. Remove generator bolts.
6. Remove water pump pulley.
7. Remove crankshaft pulley and timing belt guide plate.
8. Remove upper and lower timing belt covers.
9. Turn crankshaft so that timing mark on timing belt pulley is aligned with timing mark on engine.
10. Check that "I" mark on intake camshaft pulley is aligned with mark on cylinder head cover and "E" mark on exhaust camshaft pulley is aligned
with mark on cylinder head cover.
NOTE: Do not move camshaft or crankshaft once timing marks have been correctly positioned.
11. Loosen tensioner pulley lock bolt.
12. Protect timing belt with a rag.
13. Remove tensioner pulley.
14. Remove timing belt.
NOTE: Mark the direction of timing belt rotation (on the timing belt) for proper reinstallation.
INSPECTION
NOTE: Never forcefully twist, turn inside out or bend timing belt. Do not allow oil or grease to come in contact with timing belt.
1. Replace timing belt if it is contaminated with oil or grease.
2. Check timing belt for uneven wear, fraying, peeling, cracking and hardening. Replace timing belt as necessary.
3. Bend timing belt into a "U" shape as shown in figure. Distance "A" must be at least 1.0 inch (25 mm).
4. Inspect both idler pulley and tensioner pulley for uneven wear and smooth bearing operation.
5. Inspect camshaft pulleys and timing belt pulley for broken teeth or damage.
NOTE: Replace any component that shows damage, excessive wear, or that appears prone to a possible failure.
INSTALLATION
1. Install tensioner pulley.
NOTE: Replace tensioner spring whenever timing belt is replaced.
2. Pull tensioner pulley to its furthest point and tighten lock bolt.
3. Check that timing mark on timing belt pulley is aligned with timing mark on engine.
4. Check that "I" mark on intake camshaft pulley is aligned with mark on cylinder head cover and "E" mark on exhaust camshaft pulley is aligned
with mark on cylinder head cover.
NOTE: If existing timing belt is being reused, install belt in proper rotation direction marked prior to removal.
5. Install timing belt onto timing belt pulley first, then idler pulley, exhaust camshaft pulley, intake camshaft pulley, and tensioner pulley in that
order.
6. Check that there is no looseness in belt between idler pulley and exhaust camshaft pulley or between intake and exhaust camshaft pulleys.
7. Loosen tensioner pulley lock bolt and allow tensioner spring to apply tension to timing belt.
NOTE: Do not add additional tension.

8. Tighten tensioner pulley lock bolt to specified torque.
Tightening torque: 28 - 38 ft. lbs. (38 - 51 Nm, 3.9 - 5.2 kg-m)
9. Rotate crankshaft two full revolutions (clockwise only) and align timing mark on timing belt pulley with timing mark on engine block.
10. Check that "I" mark on intake camshaft pulley and "E" mark on exhaust camshaft pulley are aligned with marks on cylinder head cover.
11. If they are not aligned, remove timing belt and start process from tensioner installation.
12. Measure timing belt deflection by applying moderate pressure midway between camshaft pulleys. If deflection is not correct, repeat from
tensioner installation.
Deflection pressure: 22 lb. (98 N, 10 kg)
Deflection: 0.39 - 0.50 inch (11 - 13 mm)
13. Install lower and upper timing belt covers in that order.
Tightening torque: 5.8 - 8.0 ft. lbs. (7.9 - 10.7 Nm, 0.8 - 1.1 kg-m)
14. Install timing belt guide plate and crankshaft pulley.
Tightening torque: 9.0 - 12.6 ft. lbs. (12.3 - 17.2 Nm, 1.3 - 1.8 kg-m)
15. Install water pump pulley.
Tightening torque: 9.0 - 12.6 ft. lbs. (12.3 - 17.2 Nm, 1.3 - 1.8 kg-m)
16. install generator belt and adjust the tension.
17. Install P/S and/or A/C drive belt and adjust the tension.
18. Connect negative battery cable.

If the belt has got oil soaked into it could be one reason why it is coming off. Check the belt tensioner. The spring may have become weak or the tensioner bearing is bad and the pulley is wobbling.