Timing Chain Stretch (M110 Engine)
The M110 dual-overhead-cam inline-six engine uses a duplex (double-row) timing chain to drive both camshafts. Over high mileage, the chain elongates and the plastic-coated guide rails and tensioner rail deteriorate, causing timing drift, noise, and eventual risk of chain skip or breakage. The M110 timing chain system requires periodic inspection and replacement as a preventive measure on high-mileage engines.
Which models are at risk.
Warning signs to watch for.
Rattling or chattering noise from the front of the engine on cold start that may diminish as oil pressure builds
Rough or uneven idle, especially noticeable when the engine is warm
Gradual loss of power and reduced throttle response due to retarded cam timing
Hard starting, particularly when the engine is cold
Visible timing drift when checked with a timing light — timing mark wanders or is off specification
Metallic scraping sound from the timing cover area if guide rails have broken apart
Why this happens.
High mileage causing normal chain elongation — chains stretch progressively beyond 100,000 miles
Infrequent oil changes leading to accelerated chain and sprocket wear from contaminated oil
Worn or broken tensioner rail that no longer maintains proper chain tension
Guide rail deterioration — the plastic coating on the rails breaks down with heat and age, causing the steel core to wear the chain
Worn camshaft and crankshaft sprockets that no longer mesh correctly with the elongated chain
How we diagnose it.
- 01
Listen for timing chain rattle on cold start — a brief rattle that fades within a few seconds suggests the tensioner is at its limit
- 02
Remove the valve cover and inspect the upper chain run for excessive slack — more than approximately 10mm of deflection at the longest run indicates stretch
- 03
Check the chain tensioner piston extension — if it is near its maximum travel, the chain is significantly stretched
- 04
Inspect the condition of the visible upper guide rail for cracking, missing plastic coating, or breakage
- 05
Verify ignition timing with a timing light and compare to factory specification — timing drift suggests chain elongation
How we fix it.
Replace the timing chain, tensioner, and tensioner rail as a kit
Addresses the primary wear items; restores correct cam timing; widely available chain kits; prevents chain skip
Does not address guide rail condition if not included in the kit; camshaft sprocket wear is not corrected; front cover removal required
Full timing system rebuild with chain, all guide rails, tensioner, and sprockets
Comprehensive repair that addresses all wear items; restores the timing system to as-new condition; best long-term reliability
Higher cost; more labor-intensive; requires removal of the front timing cover and significant engine disassembly
Keep it from happening.
Change engine oil every 5,000-7,000 miles with high-quality oil to minimize chain and sprocket wear
Use only quality oil filters that effectively trap metal particles from chain wear
Listen for any new noises from the front of the engine and investigate promptly
Plan for proactive timing chain replacement at 150,000 miles or when any rattle is detected
Avoid extended idling, which reduces oil pressure to the chain tensioner
Common questions.
How long does an M110 timing chain last?
With proper oil maintenance, the M110 duplex timing chain can last 150,000 to 200,000 miles. However, the guide rails and tensioner rail often need attention sooner, typically around 100,000-150,000 miles. The plastic coating on the rails deteriorates with heat and age regardless of mileage, so calendar age is also a factor.
What happens if the timing chain breaks on an M110?
The M110 is an interference engine in some configurations, meaning that a broken timing chain can result in valve-to-piston contact and severe engine damage. Even if the chain does not break outright, a skip of a few teeth can bend valves. This is why preventive replacement is strongly recommended rather than waiting for failure.
Can I replace just the timing chain without the guides and tensioner?
We do not recommend replacing the chain alone. The guide rails, tensioner rail, and tensioner are all wear items that contribute to chain life. Since the labor to access the timing chain is significant, it makes no sense to reassemble with worn guides and tensioner that may fail shortly after. Always replace the full kit.
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