TIMING CHAIN, REPLACE
Caution: With the timing chain removed, avoid turning the camshaft or crankshaft. If movement is required, exercise extreme caution to avoid valve damage caused by piston contact.
1.
Disconnect and isolate battery ground cable.
2.
Drain coolant into suitable container.
3.
Remove accessory drive belt.
4.
Remove front cover as follows:
a.
Remove coolant reservoir or surge tank.
b.
Attach engine support tool Nos. J-28467-360 and J-28467-400, or equivalents, onto alternator stud-ended bolt.
c.
Remove front cover upper mounting screws.
d.
Remove engine mount and bracket adapter. Discard adapter bolts.
e.
Raise and support vehicle with jack stands.
f.
Remove righthand front wheel and tire assembly, then the righthand splash shield.
g.
Hold balancer in position using harmonic balancer GM tool No. J-38122, or equivalent, remove mounting bolt and balancer using puller GM tool No. J-24420-C, or equivalent.
h.
Remove front cover lower mounting bolt.
i.
Lower vehicle.
j.
Remove front cover and gaskets.
5.
Rotate crankshaft in clockwise direction until camshaft sprocket timing dowel pin holes line up with timing chain housing holes, Fig.
1.
6.
Remove timing chain guides.
7.
Raise and support vehicle with jack stands.
8.
Ensure timing chain slack is above tensioner, then remove tensioner, Fig.
2.
9.
Disconnect timing chain from tensioner shoe grooves and remove shoe using suitable screwdriver under timing chain while pulling shoe outward.
10.
If removing tensioner shoe is difficult, proceed as follows:
a.
Lower vehicle.
b.
Hold intake camshaft sprocket in position with camshaft sprocket wrench GM tool No. J-39579, or equivalent.
c.
Remove sprocket bolt and washer.
d.
Remove washer and install bolt into camshaft by hand.
e.
Position suitable three-jaw puller into intake camshaft sprocket relief holes and remove sprocket. Do not pry on camshaft sprocket as damage to sprocket or timing chain housing may result.
11.
Remove mounting bolts and tensioner. Caution: Tensioner is spring loaded.
12.
Mark timing chain and crankshaft sprocket for installation.
13.
Remove timing chain.
14.
Apply adhesive sealant compound GM part No. 12345493, or equivalent, on camshaft sprocket bolt.
15.
Hold camshaft sprocket in position with camshaft sprocket GM tool No. J-39579, or equivalent, then tighten mounting bolt and washer.
16.
Position camshafts using camshaft sprocket timing alignment pin tools No. J-36800, or equivalent, through camshaft sprockets' into timing chain housing holes, Fig.
1.
17.
If camshafts are out of position and must be rotated more than 1/8 turn, proceed as follows:
a.
Rotate crankshaft clockwise to 90° off TDC.
b.
Position camshafts and install dowels.
c.
Rotate crankshaft counterclockwise back to TDC. Caution: Rotating crankshaft clockwise to TDC will damage valves and pistons.
18.
Place timing chain over exhaust camshaft sprocket, coolant pump or idler sprocket and crankshaft sprocket.
19.
Remove intake camshaft timing pin and attach camshaft sprocket GM tool No. J-39579, or equivalent.
20.
Rotate intake camshaft sprocket counterclockwise with tool until timing chain can be installed over sprocket.
21.
Release tool. Timing chain tension between camshaft sprockets should tighten.
22.
Timing pin should easily fit through intake camshaft sprocket timing hole into timing chain housing timing hole. If timing pin does not fit easily, repeat procedure.
23.
With timing pins installed, raise and support vehicle with jack stands.
24.
With timing chain slack between intake camshaft sprocket and crankshaft sprocket, timing marks on crankshaft and engine block should be aligned. If crankshaft timing marks are not aligned, move timing chain one tooth forward or rearward to remove slack, then align marks.
25.
Load tensioner to zero position by forming keeper out of heavy gauge wire.
26.
Apply slight force on tensioner blade to compress plunger.
27.
Insert small screwdriver into reset access hole and pry ratchet pawl away from ratchet teeth while forcing plunger completely in hole.
28.
Install keeper between access hole and blade.
29.
Install tensioner to chain housing and inspect plunger installation again. Ensure long end is toward crankshaft.
30.
Lower vehicle enough to remove alignment dowel pins.
31.
Rotate crankshaft two revolutions clockwise.
32.
Align crankshaft keyway with cylinder block alignment mark and insert timing pins through camshaft sprockets into timing chain housing timing holes.
33.
Timing pins should slide easily through timing holes. If timing pins cannot be easily inserted, repeat procedure to properly time engine.
34.
Install timing chain guides and front cover. Torque front cover bolts to 108 inch lbs.
35.
Torque engine mount bracket adapter bolts to 81 ft. lbs., then tighten an additional 90° turn.
36.
Install accessory drive belt.
37.
Inspect cooling system and fill to proper level with recommended coolant, as required.
38.
Fill engine crankcase to proper level with recommended engine oil.
39.
Connect battery ground cable.
40.
Start engine and confirm proper operation, and ensure there are no leaks.
41.
Clear DTC(s) using a suitably programmed scan tool.
42.
These engines do not require a specified bleed procedure. After filling cooling system, run engine to operating temperature with radiator/pressure cap off. Air will then be automatically bled through opening.
Hope that helps.
