i'm having a loud knock in the cat converter mostly after the cats hot and i've shut of the engine. just keeps knocking...and knocking right inside the cat sounds like. replaced cat already..brand new cat and still knocks. can't tell if it's the metal expanding under heat..????. checked egr, no gas problems to my knowledge..i run 89. have a cai and checked manifold..what do i do? dealership has no idea and says normal, but it wasn't like that before. cut engine off and all you hear is..knock knock..delay for about 3 or 4 seconds...knock knock again..knock. any ideas? not bad when driving. only when approaching a stop light or shutting engine off.
loud knocking (or ping) in catalytic converter when truck is off --HELP!!!!
Oct 10, 2005
5 Replies
almost sounds like your describing water boiling.
Since you had the converter replaced, I'd say the noise is not coming from the converter. If nobody else hears the noise, maybe you have the problem. If you can actually demonstrate the noise then take it somewhere else. If you wait long enough perhaps the problem part will exhibit other symptoms that will make it more obvious.
aka if the radio works...turn it up louder :)
You may have stumbled into the answer Ed. Perhaps the radio is on and tuned to a station with static only. When he shuts down he inadvertently switches to accessory and the sound continues. Now what do you think about curing cancer?
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