Clinking Sound When Starts Periodically

[Mmmroth]

I recently had the timing belt and water pump changed in my 93 ls400. Now in sometimes makes a clunking sound when it fires up, but not all of the time. Sometimes it does it when it sits for a while, sometimes it does it after it's been running. I am bringing it back to my mechanic tomorrow but I was wondering if anyone had some insight on what this could be. Could this possibly be a backfire? Miss timed after installing the new belt? Thank you in advance.

[sha4000]

How many miles have you driven since the timing belt change? By clunking sound do you mean sputtering? I would take it back to the shop and let them sort it out since they did the prior work and it was not doing this before.

[landar]

Welcome to the Club, Matt.

You know, the 'clunk' might be related to the work done and it might not. Sometimes issues are just coincidental and have nothing to do with recent work.

On the other hand, I would make sure to alert your mechanic to the 'clunk' and at least let him know. That way, if something he did is at fault, and the engine stops running properly, it will be established that you did bring it to his attention.

Now, a 'clunk' to me could suggest that the mechanic forgot to properly tighten something. Maybe a bolt to the AC or Alternator bracket. Maybe even the crankshaft bolt. Who knows. It is easy to miss something like this if you get in a hurry as some do (like the roach coach pulls up at lunchtime and he suddenly smells donuts). Sometimes there is even a tool left behind that is hitting a moving part. Have the mechanic take a look.