Timing Chain: Diagnosis Lexus LX J80

Inspection

1. Inspect components for damage. Apply air pressure to oil jet to ensure passage is not restricted. Using micrometer, check amount of wear on slipper and damper. Replace slipper or damper if wear exceeds.039" (1.00 mm) from original surface.
2. Using caliper, measure length of timing chain between 16 links at several different areas on timing chain (STEP 1). (Scheme 16) Replace timing chain if length exceeds specification. See «TIMING CHAIN & SPROCKET SPECIFICATIONS»(ref-49416-S12043026682001011500000) table.
3. Wrap timing chain around crankshaft sprocket. Using caliper, measure outside diameter of timing chain with caliper contacting rollers on timing chain (STEP 2). (Scheme 16)
4. Repeat procedure on camshaft sprocket. Replace timing chain and sprocket if outside diameter measurement is less than specified. See «TIMING CHAIN & SPROCKET SPECIFICATIONS»(ref-49416-S12043026682001011500000) table.

TIMING CHAIN & SPROCKET SPECIFICATIONS

Scheme 16

Inspect components for damage. Ensure valve lifter diameter, bore diameter and oil clearance are within specification. See VALVE LIFTERS table under ENGINE SPECIFICATIONS.

1. Check camshaft journal diameter, lobe height and journal runout. Replace camshaft if not within specification. See «CAMSHAFT»(ref-49416-S08747557032001011500000) table under ENGINE SPECIFICATIONS. CAUTION: When installing camshaft to check oil clearance, camshaft end play and gear backlash, proper installation procedure of camshaft must be followed. See under «CAMSHAFT»(ref-49416-S10227661732001011500000) .
2. Install camshaft in cylinder head. Using Plastigage, check camshaft oil clearance. Check camshaft end play with camshaft bearing cap bolts tightened to specification. Replace camshaft and/or cylinder head if camshaft end play or oil clearance is not within specification. See «CAMSHAFT»(ref-49416-S08747557032001011500000) table under ENGINE SPECIFICATIONS.
3. Install camshafts in cylinder head without sub-gear on exhaust camshaft. Tighten camshaft bearing cap bolts to specification. Using dial indicator, measure gear backlash between camshaft gears. Replace camshaft if gear backlash exceeds specification. See «CAMSHAFT»(ref-49416-S08747557032001011500000) table under ENGINE SPECIFICATIONS.
4. Measure distance between ends of camshaft gear spring. Replace camshaft gear spring if distance is not .717-.740" (18.20-18.80 mm). Hold timing chain tensioner and push plunger inward. Ensure plunger moves smoothly inward and outward. Replace timing chain tensioner if plunger does not move smoothly.

Scheme 17

Scheme 18

1. For reassembly of exhaust camshaft, install camshaft gear spring, sub-gear, wave washer and snap ring on exhaust camshaft. Ensure pins on sub-gear and main gear engage with ends of camshaft gear spring.
2. Install service bolt "A" in camshaft sub-gear. see scheme 24 Using screwdriver, rotate sub-gear clockwise. Align holes of camshaft main gear and sub-gear. Install service bolt "B". Remove service bolt "A".
3. Coat thrust surfaces of camshafts with engine oil. To install intake camshaft, position camshaft so cylinder No. 1 and 4 camshaft lobes are facing downward, toward valve lifter. This will place 2-dot timing mark on intake camshaft at a 25-degree angle (STEP 2). see scheme 23 Install intake camshaft on cylinder head. CAUTION: Ensure intake camshaft bearing caps are stamped with letter "I". Install in numerical sequence with, with No. 1 bearing cap at front, No. 7 at rear, and arrow pointing forward to timing chain.
4. Lightly push intake camshaft toward front of cylinder head. Install No. 2 and 5 camshaft bearing caps on intake camshaft. Install bolts in No. 2 and 5 camshaft bearing caps. Alternately tighten bolts until No. 2 and 5 camshaft bearing caps are snug against cylinder head.
5. Install No. 3, 4, 6 and 7 camshaft bearing caps and bolts on intake camshaft. Alternately tighten bolts until No. 3, 4, 6 and 7 camshaft bearing caps are snug against cylinder head.
6. Install No. 1 camshaft bearing cap and bolts on intake camshaft. Ensure no gap exists between No. 1 camshaft bearing cap and surface of cylinder head. Alternately tighten bolts until No. 1 camshaft bearing cap is snug against cylinder head surface. Tighten all intake camshaft bearing cap bolts to specification using several steps. See «TORQUE SPECIFICATIONS»(ref-49416-S15026808592001011500000).
7. To install exhaust camshaft, rotate intake camshaft until 2-dot timing mark is at 35-degree angle (STEP 1). see scheme 23 Engage gear on exhaust camshaft with gear on intake camshaft, so 2-dot timing marks are aligned. (Scheme 17) Roll exhaust camshaft onto cylinder head. Ensure 2 dot timing marks are still aligned. CAUTION: Ensure exhaust camshaft bearing caps are stamped with letter "E". Install in numerical sequence with, with No. 1 bearing cap at front, No. 7 at rear, and arrow pointing forward to timing chain.
8. Lightly push exhaust camshaft toward front of cylinder head. Install No. 4 and 6 camshaft bearing caps on exhaust camshaft. Install bolts in No. 4 and 6 camshaft bearing caps on exhaust camshaft. Alternately tighten bolts until No. 4 and 6 camshaft bearing caps are snug against cylinder head surface.
9. Install No. 2, 3, 5 and 7 camshaft bearing caps and bolts on exhaust camshaft. Alternately tighten bolts until No. 2, 3, 5 and 7 camshaft bearing caps are snug against cylinder head surface.
10. Install No. 1 camshaft bearing cap and bolts on exhaust camshaft. Ensure no gap exists between No. 1 camshaft bearing cap and surface of cylinder head. Alternately tighten bolts until No. 1 camshaft bearing cap is snug against cylinder head surface.
11. Tighten all exhaust camshaft bearing cap bolts to specification using several steps. See «TORQUE SPECIFICATIONS»(ref-49416-S15026808592001011500000). Remove service bolt "B" from exhaust camshaft. CAUTION: Ensure service bolt "B" is removed from exhaust camshaft.
12. Ensure cylinder No. 1 is at TDC of compression stroke and timing mark on crankshaft pulley aligns with "0" mark on timing chain cover. Rotate camshafts so one-dot timing marks on sprockets are aligned. see scheme 2 Ensure 2-dot timing marks are even with cylinder head.
13. Ensure reference mark on camshaft sprocket and timing chain are aligned. Install camshaft sprocket on intake camshaft. Ensure groove in camshaft sprocket engages pin in camshaft.
14. Install distributor gear on camshaft sprocket. Ensure pin on distributor gear engages groove on camshaft sprocket. Install and tighten camshaft sprocket bolt to specification. See «TORQUE SPECIFICATIONS»(ref-49416-S15026808592001011500000).
15. Install NEW gasket for timing chain tensioner on cylinder head. Ensure gasket is properly positioned on cylinder head with front mark toward front of cylinder head. (Scheme 18) Install timing chain tensioner on cylinder head. Push timing chain, against cylinder head. Install and tighten nuts to specification. See «TORQUE SPECIFICATIONS»(ref-49416-S15026808592001011500000).
16. To check for proper valve timing, rotate crankshaft clockwise so cylinder No. 1 is at TDC of compression stroke. Ensure timing mark on crankshaft pulley aligns with "0" mark on front cover.
17. Ensure one-dot timing marks on camshaft sprockets are aligned. see scheme 2 Ensure 2-dot timing marks are even with cylinder head surface. If one-dot timing marks are not aligned, rotate crankshaft clockwise one full revolution (360 degrees), and recheck alignment.
18. Adjust valve clearance. See «VALVE CLEARANCE ADJUSTMENTS»(ref-49416-S25425254762001011500000) under ADJUSTMENTS. If spark plug tube gasket in valve cover requires replacement, pry spark plug tube gasket from valve cover. DO NOT scratch valve cover sealing surface.
19. Using Handle (SST 09951-07150) and Gasket/Seal Installer (SST 09951-00480), install spark plug tube gasket in valve cover. Coat spark plug tube gasket sealing area with grease.
20. Apply sealant on half-circular plug where it contacts cylinder head and install in cylinder head. see scheme 10 To install remaining components, reverse removal procedure. Use NEW gaskets. See «TORQUE SPECIFICATIONS»(ref-49416-S15026808592001011500000). Fill cooling system. Adjust control cables.