Thread: Knocking noise

Lynch has a good point, check for anything loose near the motor. After listening to the vid though, that noise brings back memories. Rod bearing FTL.

That's rod knock. Listen to it from 0:52 - 0:57, that's the death rattle right there.

C

Ya the thing is the noise isn't very continuous like a rod knock is.. Usually its really consistent knock knock knock so I'm not sure what to say without layin hands on it. But like I said I've heard a loose alternator make that sound.. I went to seattle to pick up a se-r for a friend an while I was drivin it back I started hearing this sound, an I'm like fuck this engine has rod knock so I pulled over popped the hood an sure enough the alt had come loose at was rattling like a mofo.. Tightend it up an was good to go!

hmm ill def have to start checking things over. thing is though there was no loss in power. if it was rod knock wouldnt there be a loss in power?

Early on in the video it sound like something is loose but towards the end it sounds a bit like rod knock. I have a motor sitting outside my house that has rod knock. I missed a shift and put it in to second gear at 120 km/h, because I was tired, angry and in a hurry. At idle and when coasting the noise wasn't too bad, but when I accelerated the noise got louder and I could feel the vibration through the gas pedal. <-- ROD KNOCK!

But Lynch might be right too. I spent alot of money a while ago replacing suspension parts at the urging of my mechanic because there was a loud jarring noise when I went over bumps. $750 later and the problem was still there and worse. He then suggested I replace the entire lower control arm assembly because the bushing was worn. At this point I figured he was just guessing so I decided to put in the wrench time myself. What did I find? A loose bolt on the lower control arm. Tightened it and the problem was FIXED!

So check all the bolts you can see first, but if the symptoms I mentioned when I had rod knock are there for you then.......

Minor rod knock wouldn't necessarily cause a noticeable loss in power.

Nope, not all the time. In the early stages it's a very distinct sound, and happens as the engine is changing speed. It trails a throttle blip by a split second. Watch the video again, and you can hear clearly at at 0:06, 0:14 and 0:16.

C

Ya like I said early in the thread its prolly rod knock but since he said he didn't notice a difference while unplugging spark plugs I figured I'd give him a few other things to check before tearing the motor apart lol

X2 that there be a rod knocking.

You should notice a difference when pulling up plug wires to drop the cylinder. Especially if its light knock it should go away completely when pulling up the wire on which cylinder is knocking. If its very very heavy knock meaning the bearing is completely gone on it then you might still hear it knock but it wont be as loud. It will have a huge difference in how loud the knock is when lifting the plug wire on that cylinder.

Again rod knock is mostly noticable when you blip the throttle. Right as the rpm reaches its peak and starts to fall it will have a knock along with it usually giving off a couple knocks before quieting. Or when holding the rpm say at 2500 steady just slightly fluctuating the throttle to bounch the rpm between 2300-2600 you will hear it with each change of the throttle position and change in rpm. Thats when its most distinct.

Valvetrain is more like a tick sound kinda high pitched. Rod knock is much lower pitched. When you have seen and heard enough of them you can instantly tell the difference.

yeah see thats the thing when i was pulling each plug wire, it didnt seem to change. the only thing that changed was the rpms from plugging the cylinder back in.