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Honda Civic and engine rattle

I have a 2000 Honda Civic, manual transmission with 91,000 miles. I have a rattle coming
from the engine, that was there before and after the timing belt was changed. I just notice
it more now after the timing belt was changed. The rattle sounds like a marble or nut
in a metal container(cylinder?). I don’t hear it with just revving the engine, only when the car
is in gear…put a load on the engine. It increases in speed as the engine speed increases
and is harder to hear or it disappears as the load on the engine decreases. It is NOT tin-y like a
a heat sheild. Could this have something to do with the pistons in the engine, the motor
mounts, or something else? Also, what kind of costs as I looking at? Thanks

Sounds like engine knock. You probably have a defective knock sensor. Is the check engine light on?

A little more background on engine knock. It comes from either too much compression or ignition timing too advanced. Modern engines use the computer to control the ignition timing. One of the inputs is from a device called a knock sensor, basically a glorified microphone. The computer advances the timing within the rest of the parameters given to it as far as it can. When knocking starts, the knock sensor sends a signal to the computer to back off the timing a bit.

The optimum timing for engine efficiency is just before it begins to knock. The knock sensor is important to maintain optimum timing. The knock will eventually cause other damage to the engine.

No lights to indicate a problem with the engine and I’m pretty/very good as far as maintenance is concerned. Should I just have this sensor checked?

Yes, any good mechanic can recognize the sound instantly. Don’t tell them in advance, just let them drive the car and see if they don’t conclude that its the knock sensor immediately. BTW, for being a glorified microphone, they can get kinda pricy.

Thanks, I’ll give it a try.