MattK
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- 05 VZ V6
Just a little didly on timing chains ....
LY7 V6 engine: stretched timing chains
In January 2006, 7.7 mm inverted tooth timing chains were introduced for the LE0, LY7 and LW2 engines, replacing 9.5 mm pitch roller chains. For some – but not all – of these timing chains, the chain links were not manufactured in accordance with design specifications and the chains could become elongated (also known as ‘stretched timing chains’). According to GM Bulletin H08-0601-01, chain elongation was expected to occur in early engine life (i.e. 10,000 kms to 20,000 kms). There have, however, been reports of timing chain elongation occurring at significantly higher kilometres.
Elongation of the timing chains would cause,
the Malfunction Indicator Lamp (MIL or ‘Check Engine’ light) to illuminate; and
the ECU to log fault codes P0008, P0009, P0016, P0017, P0018 and P0019 which indicated that camshafts on either bank of the engine were misaligned with the crankshaft.
The engines with timing chains susceptible to elongation were produced from January 2006 to engine build date 18 May 2007 (18/5/2007); this production range corresponded to engine numbers between H053340001 and H071380576.
The typical chain elongation observed was a minimum of 3 mm on a doubled-up chain. Where the timing chains had become elongated, they had to be replaced. The idlers, guiders and tensioners, however, did not require replacement, though the guides should be inspected for any abnormal wear.
LY7 V6 engine: stretched timing chains
In January 2006, 7.7 mm inverted tooth timing chains were introduced for the LE0, LY7 and LW2 engines, replacing 9.5 mm pitch roller chains. For some – but not all – of these timing chains, the chain links were not manufactured in accordance with design specifications and the chains could become elongated (also known as ‘stretched timing chains’). According to GM Bulletin H08-0601-01, chain elongation was expected to occur in early engine life (i.e. 10,000 kms to 20,000 kms). There have, however, been reports of timing chain elongation occurring at significantly higher kilometres.
Elongation of the timing chains would cause,
the Malfunction Indicator Lamp (MIL or ‘Check Engine’ light) to illuminate; and
the ECU to log fault codes P0008, P0009, P0016, P0017, P0018 and P0019 which indicated that camshafts on either bank of the engine were misaligned with the crankshaft.
The engines with timing chains susceptible to elongation were produced from January 2006 to engine build date 18 May 2007 (18/5/2007); this production range corresponded to engine numbers between H053340001 and H071380576.
The typical chain elongation observed was a minimum of 3 mm on a doubled-up chain. Where the timing chains had become elongated, they had to be replaced. The idlers, guiders and tensioners, however, did not require replacement, though the guides should be inspected for any abnormal wear.
