Timing Chain Stretch Issues

There has been a problem recently coming to light regarding some turbocharged gasoline-direct-injected (T-GDI) engines: timing chain stretch. Many experts are of the opinion that soot is responsible. Did you know that although the majority of people consider soot something of an old-fashioned diesel engine issue, T-GDI engines can actually produce more soot than a diesel with no particulate filter?

Soot is a major issue

Just like life, engine design must also come with compromise. The industry is perfectly willing to take some soot in exchange for better fuel efficiency and performance. It turns out that that little soot is becoming a big issue for a number of drivers in the form of timing chain stretch.

Soot can gather inside the motor oil of T-GDI engines. The small particles can form larger particles that cause wear and damage in your engine before the oil filter can get to them. These particles are what seems to be causing quicker timing chain stretch on many vehicles. Ford even issued a technical service bulletin (#14-0194) that recognizes the timing chain wear as an issue in some vehicles with the 3.5L EcoBoost engine.

How does soot affect timing chains?

So how does soot actually stretch timing chains? The majority of automotive timing chains are similar in appearance to bicycle chains, but on a much larger scale. Links are connected by pivoting pins, and soot can gather in the areas between the links and pins. They slowly scrub at the surface of the metal while the engine is running, expanding the clearances.

As time goes on, the timing chain will stretch; not like a rubber band, but by creating slack. The timing chain will effectively be larger in diameter. Pretty soon, your 43-inch chain will turn into a 43.1-inch+ chain, and though the tensioner can pick up some of this slack, it is finite. If the timing chain stretches more than the tensioner is capable of handling, both the camshaft and crankshaft can activate an engine code and potentially cause the engine to go into “limp” mode.

Modern oils need to protect timing chains

To fight this issue, the industry developed a test to measure an oil’s ability to fight timing chain stretch and soot buildup: the Sequence X Engine Test (ASTM D8279), part of the API SP and ILSAC GF-6 motor oil specifications introduced in May 2020.

The test uses a Ford 2.0L EcoBoost engine for a total of 216 hours of running across several cycles. After break-in, the timing chain is measured. It is also measured after the test, and the pass/fail criteria is ≤0.085% timing chain elongation.

AMSOIL protects against timing chain stretch

A number of AMSOIL synthetic motor oils passed the Sequence X Engine Test, includingSignature Series Synthetic Motor Oil, XL Synthetic Motor Oil and OE Synthetic Motor Oil, proving that AMSOIL provides outstanding protection against timing chain stretch.

Shop AMSOIL Synthetic Motor Oil

All three of these oils protect against timing chain wear in today’s T-GDI engines to protect against timing chain stretch and keep your engine running well. If you drive a T-GDI engine that’s been known to deal with timing chain stretch, like the 3.5L EcoBoost, it’s wise to use a quality synthetic oil, like AMSOIL synthetic motor oil, and a good oil filter to help fight soot buildup and timing-chain wear. These best practices will help you avoid the check-engine light and pricey dealer trips.