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STIHL 020 T

1

Service Manual

020 T Chain Saws

This manual contains detailed
descriptions of all repair and
servicing procedures for 020 T
chain saws.

You should make use of the
illustrated parts list while carrying
out repair work. It shows the
installed positions of the individual
components and assemblies.
Microfilmed parts lists are always
more up to date than printed lists.

A fault on the machine may have
several causes. Consult the
"Troubleshooting Charts" when
tracing faults.

Refer to the "Technical Information"
bulletins for engineering changes
which have been introduced since
publication of this service manual.
Technical information bulletins also
supplement the parts list until a re-
vised edition is issued.

The special servicing tools mentioned
in the descriptions are listed in the last
chapter of this manual. Use the part
numbers to identify the tools in the
"STIHL Special Tools" manual.
The manual lists all special servicing
tools currently available from STIHL.

Service manuals and all technical
information bulletins describing
engineering changes are intended
exclusively for the use of STIHL
servicing dealers. They must not be
passed to third parties.

Always use original STIHL
replacement parts.

They can be identified by
the STIHL part number, the

STIHl

 logo

and the STIHL parts symbol 

(

The symbol may appear alone on
small parts.

STIHl

© 1999, Andreas Stihl AG & Co., Waiblingen

Servicing and repairs are made
considerably easier if the machine
is mounted on the assembly stand
(1). This enables the machine to be
swivelled to the best position for the
ongoing repair and leaves both hands
free.

The machine is secured to the stand
by means of the guide bar mounting
nut (after removing the sprocket
cover).

Summary of Contents for 020 T

Page 1: ...in the descriptions are listed in the last chapter of this manual Use the part numbers to identify the tools in the STIHL Special Tools manual The manual lists all special servicing tools currently av...

Page 2: ...k Plug 29 5 2 Spark Plug Terminal 31 5 3 Ignition Lead 31 5 4 Ignition Module 32 5 4 1 Ignition Timing 32 5 4 2 Removing and Installing 33 5 5 Flywheel 33 5 6 Ground Wire Short Circuit Wire 34 6 Rewin...

Page 3: ...in 40 mm 1 57 in 28 mm 1 10 in 7 41 1 1 6 kW 2 2 bhp 1 8 Nm 1 3 Ib ft at 7 500 r p m 14 000 r p m 2 800 r p m Crankshaft supported in heavy duty roller bearings needle cages on small and big ends 9 m...

Page 4: ...magneto ignition breakerless with integral trigger unit 0 25 mm 0 010 in 2 0 2 8 mm B T D C at 8 000 r p m 24 7 32 5 B T D C at 8 000 r p m Bosch WSR 6 F or NGK BPMR 7 A 0 5 mm 0 020 in M14x1 25 9 5 m...

Page 5: ...IS M 4x12 IS M 4x12 IS M 4x16 IS M 4x16 IS M 4x20 IS M 5x12 IS M 5x16 M 5 M 8x1 M 8x1 L M 14x1 25 IS P 5 IS M 4x16 IS P 4x14 IS P 6x21 5 IS P 4x10 For component Chain catcher Insert chain brake Handle...

Page 6: ...dle cage damaged Clutch shoe retainer broken Clutch shoes and carrier worn Chain not properly tensioned Chain not properly tensioned Poor chain lubrication Worn chain sprocket Brake spring broken Brak...

Page 7: ...se damaged Manifold leaking Cylinder base gasket leaking Crankcase damaged cracks Secondary air seepage through poorly mounted or faulty manifold Piston rings leaking or broken Muffler carbonized Insu...

Page 8: ...ow produce sparkover Does flywheel appear to be in good condition Fit new spark plug Is air gap correct Adjust air gap 0 25 mm 0 010 in Is spark test positive Insert screwdriver in place of spark plug...

Page 9: ...rter rope Fit new rewind spring Fit new rewind spring Fit new pawl Fit new spring clip Thoroughly clean complete starter mechanism Apply a few drops of kerosine paraffin to spring then pull rope caref...

Page 10: ...ition Idle jet too lean Main jet too lean Inlet control lever too low relative to design position Inlet needle sticking to valve seat Connecting bore to atmosphere blocked Remedy Fit new pump housing...

Page 11: ...l strainers dirty Remedy Fit new diaphragm gasket Fit new metering diaphragm Reset idle speed adjusting screw by idle speed adjusting screw correctly Clean jet bores and ports with compressed air Scre...

Page 12: ...row side is next to the series number e g 1129 3 Fit the clutch shoes over the arms 1 of the clutch carrier so that the series number is on the same side as the larger hexagon 2 Use assembly hook 2 to...

Page 13: ...Take out screws 1 Remove the segment 2 Take the needle cage out of the sprocket Clean stub of crankshaft Wash needle cage in clean white spirit and lubricate with grease see 11 2 Replace damaged needl...

Page 14: ...e 2 Locate the hand guard and bell crank on the pivot pins Now press the flat spring 1 down and push the hand guard and bell crank fully home Fit flat spring 1 in position Ease the hand guard 1 and be...

Page 15: ...nchor pin Fit the segment and tighten screws to 3 2 Nm 2 4 Ibf ft Remove the thrust pad 1 Rotate the spur gear 2 to unscrew the adjusting screw 3 fully from the tensioner slide 4 Hook the brake spring...

Page 16: ...carburetor and crankcase tester and the vacuum pump Take out the screws Lift lower casing away from upper casing Troubleshooting chart see 2 2 Remove sprocket cover see 3 1 Take out the screw 1 Remove...

Page 17: ...g screws Remove the carburetor see 10 2 1 Check that washer 1 and sleeve 2 are in position Connect tester s pressure hose to nipple on test flange Make sure the spark plug is properly tightened down R...

Page 18: ...the piston s induction stroke because there is no internal counterpressure An additional test can be carried out with the vacuum pump to detect this kind of fault The preparations for this test are t...

Page 19: ...and oil seal with grease see 11 2 Ignition side Remove the flywheel see 5 5 Apply the puller as at the clutch side and pull out the oil seal Important Take special care not to damage crankshaft stub...

Page 20: ...onnecting rod Release and unscrew the four cylinder base screws through the holes in the cylinder fins Pull the cylinder off the piston Remove the cylinder gasket Use a scriber or similar tool to ease...

Page 21: ...ards the flat face 2 of tool s shank Fit the piston pin 1 on the assembly drift 2 and slide it into the piston the pin slides home easily if the piston is hot Thoroughly clean the gasket seating surfa...

Page 22: ...the cylinder with oil and line it up so that it is positioned as it will be in the installed condition It is essential to observe this point as the piston rings might otherwise break Slide the cylind...

Page 23: ...4 6 Crankcase 4 6 1 Removing the Crankshaft 4 5 Piston Rings Install the new piston rings in the grooves so that the radii face upward Install the piston see 4 4 2 Note If the flywheel is stuck screw...

Page 24: ...ews 3 and remove the oil pump Pull out the plug Take out the screws 1 and 3 Withdraw the chain tensioner 2 Remove the piston see 4 4 1 Take out the screws 1 Remove the cover 2 Pull off the worm Take o...

Page 25: ...t always be replaced as a complete unit in the event of damage to any one of these parts When fitting a replacement crankshaft always install new oil seals and roller bearings Pull the ignition lead 1...

Page 26: ...the mating surfaces they must be cleaned very thoroughly to ensure a perfect seal Note If a new crankcase is installed stamp the machine number on the crankcase with 2 5 mm 0 1 figure stamps Fit the...

Page 27: ...Use M8 stud puller to screw in stud as far as stop Place bumper strips in position and press them home as far as they will go Push pickup body 1 through the hole and locate the flange 2 on the suction...

Page 28: ...oller bearing 1 as far as stop into ignition side of crankcase Lubricate bearing with oil Push ignition lead 1 through the grommet 2 Slide the oil seal closed side facing the crankcase over the clutch...

Page 29: ...ble because they have longreach electrodes Sooted or carbonized spark plug Use brass wire brush to clean the spark plug and then blow it clear with compressed air Note Never use a steel wire brush for...

Page 30: ...t to ground In this case the engine with either not start or only run erratically To install the spark plug Clean the spark plug seat and inspect the sealing ring to make sure it is in good condition...

Page 31: ...o the terminal so that the leg spring locates properly inside it Fit terminal on spark plug and refit chain sprocket cover Unhook the leg spring from the ignition lead Slip the spark plug terminal off...

Page 32: ...The ignition module accommodates all the components required to control ignition timing There are two electrical connections on the coil body 1 the high voltage output 2 the connector tag for the shor...

Page 33: ...ull the short circuit wire 1 off the ignition module and out of the retainer 2 Pull the ignition module forwards Unscrew the ignition lead from the contact pin and pull it out of the high voltage outp...

Page 34: ...ing screw 1 and screws 2 from annular buffer 3 Remove the annular buffer Note Thread short circuit wire through the side of the crankcase and pull it up to the top Inspect the condition of the flywhe...

Page 35: ...ope see 6 3 Troubleshooting chart see 2 4 Take out the fan housing mount ing screws and remove the fan housing Relieving tension of rewind spring Pull out the starter rope about 5 cm 2 and hold the ro...

Page 36: ...t before installation see 11 2 The retainer 1 slips off as the rewind spring is pressed into the fan housing Engage the anchor loop 2 over the lug in the fan housing Caution The rewind spring can pop...

Page 37: ...r seven full turns clockwise Note The rewind spring is correctly tensioned when the starter grip sits firmly in the rope guide bush without drooping to one side If this is not the case tension the spr...

Page 38: ...se see 11 2 and fit it in position Pull starter rope out of recess 1 in rope rotor Undo the knot 2 Pull starter rope out of rope rotor and guide bush Use a suitable tool to pry the old bush out of the...

Page 39: ...t lower annular buffer Remove the fan housing see 6 2 Remove the center screw Remove front handle mounting screw from annular buffer Remove the annular buffer Place annular buffer in position Tighten...

Page 40: ...osition START warm start starting throttle choke shutter open CHOKE cold start starting throttle choke shutter closed Remove the Master Control lever see 8 1 Take out the screws Remove the handle mold...

Page 41: ...ee 7 Pull out contact spring 1 for ground wire 2 Disconnect the ground wire Pull the short circuit wire off the contact spring Push the contact spring 2 slightly to one side and fit the switch shaft 1...

Page 42: ...e double lever Assemble in the reverse sequence Remove the switch shaft see 8 4 Take out the upper front handle mounting screw Take out lower front handle mounting screw Note Note that short choke rod...

Page 43: ...Raise handle housing slightly and push manifold flange out of intake opening in handle housing at the same time Fit the manifold in the handle housing intake opening as follows Wind a piece of string...

Page 44: ...t check the oil tank and the pickup body Clean the oil tank if necessary Troubleshooting chart see 2 5 Remove the chain sprocket see 3 3 9 CHAIN LUBRICATION 9 1 Suction Hose Pickup Body Push suction h...

Page 45: ...e chain sprocket see 3 3 Fit the oil tank filler cap Pull out the upper bumper strip A valve is installed in the tank wall to keep internal tank pressure equal to atmospheric pressure Cleaning the val...

Page 46: ...pump Remove the oil pump see 9 3 1 Drive out the roll pin 1 with a 2 mm 0 08 drift Pull out the adjusting screw 2 and remove the 0 rings 3 Remove the plug 4 Take out the pump piston 5 with spring 6 an...

Page 47: ...loths Note If filter is damaged install new part immediately Installation is a reversal of the removal sequence Ease the grommet off the adjusting screws and pull it out of the handle housing Dirty an...

Page 48: ...or sealing cone of inlet needle is damaged or inlet control lever sticking 2 The metering diaphragm is damaged In either case the carburetor must be removed and serviced After completing test open th...

Page 49: ...ng cone of the inlet needle it will be necessary to replace the inlet needle because it will no longer seal properly This is indicated by constant flooding of the carburetor even though the needle is...

Page 50: ...ge clevis in annular groove on the head of the inlet needle and tighten down the round head screw Make sure that the helical spring locates on the control lever s nipple Check easy action of the inlet...

Page 51: ...sket are held in position by inte grally cast pegs on the end cover Remove the E clip Insert the fuel strainer at the pump side Fit the pump diaphragm Removing the throttle shaft Unscrew the throttle...

Page 52: ...ring end cover 2 and the inner hole 3 towards the torsion spring 4 Coat the fastening screw with Loctite see 11 2 and tighten down firmly Carry out the leakage test see 10 2 2 Install the carburetor s...

Page 53: ...kwise for richer mixture at sea level Turn screws very slowly and care fully even slight adjustments produce a noticeable change in engine running behavior Corrections to high speed adjusting screw Th...

Page 54: ...event of trouble with the fuel supply system always check the fuel tank and the pickup body first Clean the fuel tank if necessary Cleaning the fuel tank Unscrew the filler cap and drain the tank Pour...

Page 55: ...using see 8 8 Take out fan housing mounting screws Remove the fan housing Note Press in valve as far as stop Use a screwdriver to carefully raise the rear of the handle housing slightly Position filte...

Page 56: ...wards disconnect impulse hose from nipple and then remove tank housing Remove filter element 1 and valve 2 of tank vent Take out the insulating plate 1 Reassemble and install in the reverse sequence N...

Page 57: ...7 2205 5910 893 2407 0812 542 2104 5910 893 5608 5910 890 0301 5910 890 0302 5910 890 0311 5910 890 0312 1116 893 4800 0000 890 2201 5910 893 8800 5910 890 2301 5910 890 2420 5910 890 8210 5910 850 31...

Page 58: ...R 10 m 33 Electrician s repair kit Graphite grease Molykote grease Part No 0781 120 1111 0781 120 1109 0786 111 1109 0781 417 1315 0000 930 2251 0000 007 1013 Application Oil seals oil pump drive chai...

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