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Hot take: Rushing through a timing belt change cost me an engine | Auto Mechanics - The Community Guide

Hot take: Rushing through a timing belt change cost me an engine

I was in a hurry last week, had a customer breathing down my neck. Figured I could skip double checking the timing marks because I've done it a hundred times. Got everything back together, started it up, and heard this awful clunking sound. Turns out I was off by one tooth on the cam gear. Valves met the pistons, and the engine was toast. Now I'm dealing with a pissed off customer and a big repair bill. Seriously, no matter how many times you've done it, verify the timing every time. It's a simple step that saves you from disaster.

3 comments

3 Comments

jessica_green296mo ago

Wait, off by one tooth and it completely totaled the engine? That seems a bit extreme. I've seen engines run rough but survive a single tooth being off. Are you sure it wasn't already having other issues, or maybe something else got messed up during the reassembly? Sometimes it's easier to blame the one skipped step than admit something else went wrong.

green.robert6mo ago

Yeah, the "something else got messed up" part is key. Seen shops blame the belt because it's the obvious mistake, when really a bent valve from an old overrev was waiting to fail.

kelly_hart286mo ago

Maybe you just have a magic touch, but one tooth off on an interference engine is a pretty sure way to make some expensive noises. It's not always a total loss, but it's a gamble I wouldn't take. I'm with green.robert on this, sometimes the failure was already waiting to happen, but skipping the check is still asking for trouble. The whole point is that verifying marks is the one thing that stops you from being the cause, or from getting blamed for a past problem. It's a five minute step that saves you from a five thousand dollar argument.