On New Years Eve 2015, my family and I were driving eastbound down the Ohio turnpike in my beloved 2002 Saturn L300. Everything was fine until, just past the Route 250 exit, the IP lit up like a Christmas tree and the engine suddenly lost power. Fortunately, I was able to coast to a safe spot on the shoulder. Unfortunately, that was the beginning of a miserable ordeal that finally ended with me discovering that the Saturn’s timing chain had broken and the engine was mulched.
That generation of Saturn was powered by GM’s L61, a 2.2-liter, dual overhead cam, inline four that General Motors used in a bunch of its small vehicles in the early aughts. Now, if you know anything about GM engines, you might know that the L61 is an interference engine. That means that when the engine is running, the valves and the pistons occupy the same space. They don’t do this at the same time, obviously, and they’re kept from doing so by the timing chain. If the timing chain breaks, however, you get a situation that we in the industry like to describe as no bueno.
Never the twain shall meet
When a timing belt or chain breaks, it severs the link between the crankshaft and the camshaft(s). This causes the valvetrain to stop moving while the crankshaft and pistons continue to work. With the valvetrain stopped, one or more valves will be stuck in the open position, and these open valves will be protruding into the space where pistons go. The pistons then come up on the compression or exhaust stroke and slam into the open valves. This will likely happen hundreds, if not thousands, of times before you can get the engine turned off, and by that point, the damage is already done.
What kind of damage? The really nasty, expensive kind of damage. Getting battered by a piston a few thousand times will bend the open valves or snap their heads off. The piston itself may get gouged or even punctured, and any debris from broken valves can damage cylinder walls. In some very unlucky cases, the connecting rods themselves might get damaged. All of this happens in the blink of an eye, and it renders the engine useless until it’s repaired.
The good thing is that this kind of carnage is preventable. Every car, whether it has a timing belt or a timing chain, has set intervals for timing belt or chain maintenance and replacement. Sure, replacing a timing belt or chain is a pain and can be pricey, but it’s cheaper than replacing a whole engine or scrapping the car. Oh, and my old Saturn? I ended up slapping a salvaged engine in it and driving it for four more years until I traded it in for a Kia Soul, one of the smaller cars readers said America should love.