When is it a good time to replace the timing chain?

Tiny
PHILTAVO
  • MEMBER
  • 2007 LEXUS GX 470
  • V8
  • 4WD
  • AUTOMATIC
  • 148,000 MILES
With the high mileage on my vehicle, it was suggested that I replace the timing chain as a preventative measure to avoid really costly repairs down the line. There is no reason to think it's failing now, no noise or rattles. I was told that it is time for this costly maintenance. What say you?
Monday, March 15th, 2021 AT 10:48 AM

1 Reply

Tiny
ASEMASTER6371
  • MECHANIC
  • 52,797 POSTS
Good afternoon,

The recommended time is 150,000 to 175,000 miles. Beyond that, you are on borrowed time.

https://www.2carpros.com/articles/how-a-timing-belt-works

Roy

TIMING BELT

COMPONENTS (Part 1)
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COMPONENTS (Part 2)
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COMPONENTS (Part 3)
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COMPONENTS (Part 4)
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REMOVAL
1. DRAIN ENGINE COOLANT
2. SEPARATE BATTERY NEGATIVE TERMINAL
3. REMOVE V-BANK COVER SUB-ASSEMBLY
(a) Remove the 2 nuts and V-bank cover sub-assembly.

4. REMOVE ENGINE ROOM COVER SIDE
5. REMOVE ENGINE ROOM SIDE COVER LH
6. REMOVE AIR CLEANER HOSE ASSEMBLY
7. REMOVE RADIATOR SUPPORT SEAL UPPER
(a) Remove the 11 clips and radiator support seal upper.

8. REMOVE FAN AND GENERATOR V BELT

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9. REMOVE FAN WITH FLUID COUPLING
(a) Unfasten each clip and the 2 hose clamps, and then separate the 2 oil cooler hoses from the fan shroud.
(b) Remove the 3 bolts and separate the fan shroud from the radiator.
(c) Remove the 4 nuts and separate the fan with fluid coupling from the engine.
(d) Remove the fan shroud and fan with fluid coupling together from the vehicle.
(e) Remove the fan pulley.

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10. SEPARATE VANE PUMP ASSEMBLY
(a) Disconnect the vacuum hose.
(b) Remove the nut, 2 bolts and vane pump assembly.

HINT: Hang up the hoses instead of detaching.

11. REMOVE GENERATOR ASSEMBLY

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12. SEPARATE COMPRESSOR
(a) Disconnect the compressor connector.
(b) Remove the nut, 3 bolts, compressor stay and compressor.

HINT: Hang up the hoses instead of detaching.

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13. REMOVE NO. 2 IDLER PULLEY SUB-ASSEMBLY
(a) Remove the pulley bolt, cover plate and idler pulley.

14. REMOVE OIL COOLER PIPE
(a) Disconnect the 3 hoses.
(b) Remove the bolt, nut and oil cooler pipe.

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15. REMOVE NO. 3 TIMING BELT COVER SUBASSEMBLY LH
(a) Remove the grommet and separate the cam position sensor connector from the No. 3 timing belt cover sub-assembly LH.
(b) Remove the 4 bolts and No. 3 timing belt cover subassembly LH.

16. REMOVE NO. 2 TIMING CHAIN OR BELT COVER
(a) Remove the nut, 3 bolts and No. 2 timing belt cover.

17. REMOVE NO. 2 TIMING BELT COVER SUBASSEMBLY
(a) Remove the 2 bolts and No. 2 timing belt cover subassembly.

18. REMOVE V-RIBBED BELT TENSIONER ASSEMBLY
(a) Remove the bolt, 2 nuts and V-ribbed belt tensioner.

19. REMOVE FAN BRACKET SUB-ASSEMBLY
(a) Remove the 2 nuts, 2 bolts and fan bracket subassembly.

20. REMOVE CRANKSHAFT DAMPER SUB-ASSEMBLY

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(a) Using SST, remove the pulley bolt.
SST 09213-70011 (09213-70020), 09330-00021

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(b) Using SST, remove the crankshaft pulley.
SST 09950-50013 (09951-05010, 09952-05010, 09953-05010, 09953-05020, 09954-05021)

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21. REMOVE TIMING BELT NO. 1 COVER
(a) Remove the 4 bolts and timing belt cover.

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22. REMOVE NO. 1 CRANKSHAFT POSITION SENSOR PLATE
(a) Remove the No. 1 crankshaft position sensor plate.

23. REMOVE TIMING BELT

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(a) If reusing the timing belt, check the installation marks on the timing belt.
(1) Check that there are 3 installation marks on the timing belt by turning the crankshaft as shown in the illustration.
If the installation marks have disappeared, put a new installation mark on the timing belt before removing each part.
(b) Set the No. 1 cylinder to approximately 50° BTDC/compression.

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(1) Using the crankshaft damper bolt, turn the crankshaft to align the timing marks of the crankshaft timing pulley and oil pump body.

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(2) Check that the timing marks of the camshaft timing pulleys and timing belt plates are aligned.
If not, turn the crankshaft 1 complete revolution (360°).

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(3) Using the crankshaft damper bolt, turn the crankshaft counterclockwise by approximately 50°.

NOTICE: If the timing belt is disengaged, having the crankshaft pulley at a wrong angle can cause the piston head and valve head to come into contact with each other when removing the camshaft timing pulley and camshaft, causing damage. So always set the crankshaft pulley at the correct angle.

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(c) Alternately loosen the 2 bolts, then remove the bolts, the chain tensioner and dust boot.

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(d) Using a SST, loosen the tension between the camshaft timing pulley (RH bank) and crankshaft timing pulley by turning the camshaft timing pulley (RH bank) counterclockwise slightly.
SST 09960-10010 (09962-01000, 09963-00350)
(e) Disconnect the timing belt from the No. 1 timing belt idler and remove the timing belt.
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Monday, March 15th, 2021 AT 1:26 PM

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