Isuzu Trooper II 1986 Manual page 7

Disconnect negative battery cable. Drain cooling system.
Disconnect radiator hoses. Remove radiator. Remove all drive belts.
Remove fan. Remove vibration damper assembly. Pry seal out of front
cover/timing belt cover.
Installation
Using Seal Installer (J-26587), install new seal in cover.
Coat oil seal lip with oil. Reverse removal procedure to complete
installation.
TIMING CHAIN & SPROCKETS (1.9L MODELS)
Removal
Remove front cover. Lock chain tensioner in retracted
position. Remove timing chain from sprockets.
Inspection
1) Check camshaft and crankshaft sprockets for wear or
damage. If crankshaft sprocket replacement is required, remove
sprocket using Puller (J-25031).
2) Using spring scale, check timing chain for stretch. Apply
22 lbs. (10 kg) of tension to chain and measure length of 40 chain
links. See Fig. 5.
3) Length of chain should be 15" (381 mm). If length exceeds
15 5/32" (385 mm), replace chain. Check chain tensioner, tensioner
guide pins, guide rail, and chain guide for wear. Replace as
necessary.
4) Ensure that tensioner guide rail and chain tensioner move
freely on guide pins. Ensure that oil jet in chain guide is not
plugged. If oil jet is removed, install oil jet with hole pointing
toward crankshaft.
Fig. 5: Timing Chain Stretch Test On 1.9L Models
Courtesy of Isuzu Motor Co.
Installation
1) Install timing sprocket and pinion gear with grooved side
toward front cover. Turn crankshaft so that key groove is facing
upward (No. 1 piston on TDC).
2) Install timing chain by aligning chain marked plate with
mark on crankshaft sprocket. Ensure that side of chain with most
links between marked plates is on chain guide side of engine. See
Fig. 6.
3) Install chain on camshaft sprocket. Ensure that marked
plate aligns with triangular mark on sprocket. Install sprocket on