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Last Tuesday, my timing belt sheered off several teeth. I got one on order and replaced it, and the car fired right up. I was able to hand crank the engine several times after re-timing it and it turned without any sort of binding/difficulty beyond fighting the springs.

Now, I've noticed while driving it, it sounds much deeper at the exhaust end of things. I didn't actually take apart anything along the airflow path. I just took out the spark plugs (so I wouldn't fight compression when hand cranking it) and the serpentine/timing belts.

So my question is, why would replacing the timing belt (and tensioner/pulleys/water pump) change the sound of the engine? Is it possible a worn out tensioner could be the culprit here, or perhaps a stretched belt?

Community
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Sidney
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2 Answers2

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There is a chance that your belt had some offset (1 tooth for example) and your exhaust valve was opening earlier/later. Now your belt is ok and sounds different.

Dzianis Yafimau
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Tighter valve adjustments sounds like a choked motor and will stall when low on gas, looser valve adjustments sound more like a Harley but too loose and you will hear clatter(bad valves are slapping against something, this can also happen if you run 87 in a 10:1 ratio cylinder) or a diesel sound, which isn't necessarily bad. If by messing with your timing belt, you made your valves operate by a slightly different time, that could be the reason. Also if the teeth keep wearing out, you may be experiencing delayed firing of certain cylinders or gasoline igniting in places it shouldn't like your exhaust. It also could be that you have your boost adjusted or one of your spark plugs has a burn mark on the end of it.

GettingNifty
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