Engine vibrates and knocks only at a certain rpm. Goes away when I lower that rpm or raise it higher.?
A rod knock occurs at all RPM’s
Tester
Do you know what may cause a knocking noise at a certain rpm? I have bad motor mounts and supposedly bad control arm.
If the vehicle has an automatic transmission, I’ve heard a cracked flex plate make a knocking noise at a certain RPM.
Tester
Thank you. Is this severe or a safety concern?
Also it’s not a consistent sound. It sounds more of a creaking noise along with vibration and sometimes I can’t replicate it but it happens 30-40% of the time. It’s not a constant ticking if that helps
Would it be fair to ask what engine you are listening to? Not all engines have pushrods.
Once your reach that rpm, does the sound change when you then rapidly accelerate in gear? What if you shift into neutral and coast? Do you hear this sound if you increase the rpm to that same range when idling in the driveway?
It’s a 3.5l 2004 kia amanti
So when I reach the thumping RPM, as Soon as I speed up or slow down OR let go of the pedal, the sound goes away. As for idling, I sat in PARK and reach the RPM and I get no noise. So it only seems to be while in drive?
The thumping/vibration only lasts 4 seconds maximum. And that’s probably because I cruise anyway. Always letting go of the pedal.
i DO have bad motor mounts but THAT noise happens when I suddenly take off or break.
Do you get the sound if you rev it while stationary in neutral/park?
If so, have a helper rev it while you listen under the hood.
It does not
I see now my question was redundant. I missed that.
So it could be in the transaxle or driveshafts .
What did you break?
Do you plan on replacing that broken part?
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Plan on replacing your English language for a new one my friend
Could be the motor mounts. You know they’re bad, replace them.