ON MY 1999 DAEWOO NUBIRA I HAVE AN OIL LEAK DOWN BY THE OIL FILTER BEHIND THE LOWER REAR TIMING BELT COVER.IT SPRAY OUT IN A SMALL STREAM WHEN EVER I CRANK THE CAR.

after you remove the timing belt covers on the crankshaft gear have a noch face down to alaing tho the oil pump cover on the camshafts have two marks a the top of timing cover

1995 Tracker would have a timing BELT. Normal oil leak points (in order) on a Suzuki G16 engine are the distributor base (rear of motor), valve cover (top of motor), front main seal (behind lower timing belt cog) cam seal (behind the upper timing belt cog) and rear main seal. (behind the flywheel). I'd suspect the front main seal or cam seal. I use foot power to help find oil leaks.

The oil filter is not so easy to locate. It is on the bottom right hand sode of the engine. You need to look down between the small gap between the drive belt and timing belt cover. You need to access it from under the engine near the right front wheel access is limited due to the plastic splach guard under the engine. This guard is usually held on by screws or bolts. Take it off and you should be able to get access to the filter.

Source: ehow.com

TIMING BELT
Removal
Disconnect negative battery cable. Disconnect intake air temperature sensor connector from intake air duct. Disconnect the air intake tube from the throttle body. Disconnect the breather tube from the valve cover. Remove resonator from throttle body. Remove air filter housing.
Raise and support the vehicle. Remove right front wheel. Remove right front splash shield from wheelwell. Remove serpentine accessory drive belt.
Remove crankshaft pulley bolts. It is NOT necessary to remove crankshaft sprocket center bolt. Remove crankshaft pulley. Lower vehicle.
Support engine assembly from above with Support Fixture (J-28467-B). Remove engine mount bracket from timing belt end of engine.Remove power steering hose clamp bolt, and position hose away from timing belt cover. Remove front timing belt cover. Using crankshaft center bolt, rotate crankshaft one full turn clockwise (as viewed from timing belt end of engine).
Align mark on crankshaft sprocket with notch at bottom of rear timing belt cover. See Fig. 4 . Align camshaft sprocket timing marks with notches on valve cover. See Fig. 5 .
CAUTION: Engine damage could result if camshaft sprockets are not properly aligned with notches on valve cover.
Loosen the automatic tensioner bolt. Use an Allen wrench to rotate tensioner and relieve tension on timing belt. Remove timing belt.
Fig. 4: Aligning Crankshaft Sprocket Timing Mark
Courtesy of DAEWOO MOTOR AMERICA, INC.

Fig. 5: Aligning Camshaft Sprocket Timing Marks
Courtesy of DAEWOO MOTOR AMERICA, INC.

Installation
Ensure crankshaft and camshaft timing marks are still aligned. Install the timing belt. See Fig. 7 . Turn the timing belt tensioner counterclockwise to tension the timing belt. Turn tensioner until the pointer aligns with the notch on the rear timing belt cover. Tighten automatic tensioner bolt to specification. See TORQUE SPECIFICATIONS .
Using crankshaft center bolt, turn crankshaft clockwise (as viewed from timing belt end of engine) 2 full revolutions. Ensure timing belt tensioner pointer is still aligned with notch.
If timing belt tensioner is correctly aligned, install timing belt cover. See Fig. 3 . Install the engine mount bracket on the timing belt end of engine. Position power steering hose in place, and install clamp bolt. Install crankshaft pulley. Install serpentine accessory drive belt.
Install right front splash shield. Install right front wheel. Install air filter housing and resonator. Connect air intake temperature sensor connector. Connect negative battery cable.
Fig. 7: Identifying Timing Belt Routing
Courtesy of DAEWOO MOTOR AMERICA, INC.

here

http://www.2carpros.com/questions/daewoo-leganza-2000-daewoo-leganza-timing-marks

have your car change oil regulary. timing belt must check if at normal state. or have replace it.
also tune -up your vehicle first, and try new spark plugs, distributor cap, ignition coil. also have your air filter replace maybe dirty.

no dont need to take belt off if its twin cam by the sound of things
just top bolt which is inside cam belt cover remove top cam cover retainer clip in top centre if still there and then 10mm bolt in cam belt cover just down from top middle section of cover bend gently to get to cam sensor bolt if have too much trouble doing this whole cam belt cover needs removing, air box, accessory drive belt and engine mount will need jack to support engine and to reinstall mount

remove eng cover. it is at the front of eng neer timing belt, to re place timing belt must come off good luck

no timing marks on cover, timing marks are on sprokets they should be lined oposite each other.

Here is a pic if the timing marks two small marks on the cam pulleys and one small cut away on the crank pulley .

The oil pressure release valve is located behind a large 3/4 lug on the oil pump, if you raise your vehicle and locate the oil filter, look up and to the right of the pressure sender switch, this nut should face to the rear of the of the car, undo it but have a cloth handy as oil will spill quite heavy from this once removed. Inside there will be a spring, remove the spring and to follow will be the valve, if the valve has a problem feed then you will have some trouble removing. Use a scribe to remove along with some (INOX) spray, spray it into the location and leave it for about 20 mins.