weird knocking sound ??

ok, heres the deal. today my car started making this knocking sound. my first thought was spun rod bearing. then a piston rod knocking, then detonation, then supercharger coupler. rod bearing it isnt. oil is clear and the knock goes away when under load or when revved higher. the same for the piston rod knock and detonation. it was a slow steady knock so it cant be the supercharger, which spins at about 3 times the engine's rpm. now here's where it gets interesting. i cannot hear it in the engine bay or underneath the car. AT ALL!! i can only hear it from inside the car. it does it in every gear when im under about 1300 rpm and its very pronounced at idle. it sounds like its coming from the transmission area, but i cant think of what would cause this sound. no other problems at all, except for my cam sensor. i think thats going out because occasionally it'll show my idle at 500 rpm, and when i give it gas and let off, the needle is really jerky between 1000 and 2000 rpm. anyone??

I once had a ticking sound just like a lifter tic.I was just a exhaust leak.
I tightened my header bolts and the tic went away.

Rand

You could have a lifter knock when you rev it up the oil pressure goes up and it stops.. Try changeing your oil and doing a flush you may have picked up a little trash in your lifter..

its not a ticking. i have that exhaust ticking you're talking about randy. its not that. its a solid knocking sound. im going to try the oil flush thing and see if that helps. thanks

I a similar problem with mine. Turns out that is was 2 of the 6 rod bearings were bad. It was all result of the harmonic balancer which was close to flying apart. It did no major damage to the crank or rods, still don't understand how it didn't, but they would fall out of the rod after I reinstalled them in the rod end. Seems like they formed around the crank due to all the pressure.

could there be any way this knocking could be related to the torque converter? the sound goes away when the car warms up. it'll also go away if i put it in gear and powerbrake it to about 1400-1500 rpm. im really hoping it doesnt have anything to do with the rod bearings as hock was saying though..

Knocking

specops_SC said:

could there be any way this knocking could be related to the torque converter? the sound goes away when the car warms up. it'll also go away if i put it in gear and powerbrake it to about 1400-1500 rpm. im really hoping it doesnt have anything to do with the rod bearings as hock was saying though..

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Hope you get to the bottom of this. My 92SC started doing the same thing last spring. This was about a year after my harmonic balancer went out--don't know if it has anything to do with it. Mine quits making the noise as soon as it warms up as well. My SC has about 180,000 on it and I figure I'll just drive it til she quits unless someone can convince me it is worth the $'s to tear into and find the problem.

A little more explaining

Before I tore my engine down it would make a knocking noise at start up. It wasn't loud and I still had good oil pressure. I also had a vibration around 1500 rpms due to the balancer being bad.

i was talking to a guy earlier today who has a 5.0 thunderbird that has that same knock at startup. he literally tore the motor down in an effort to get rid of the sound, but its still there, which led him to believe that it's transmission related, most likely torque converter. would a tc be capable of making this kind of knocking sound?

Moses

Flex plate?

TC to flex plate bolts loose??
Pull inspection plate and rotate TC and inspect for loose bolts....

BobGPz said:

TC to flex plate bolts loose??
Pull inspection plate and rotate TC and inspect for loose bolts....

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that actually makes the most sense, except for the fact that the sound goes mostly away when the car warms up. maybe expanding metal puts pressure on loose bolts? im going to put it on a lift this weekend and see if i cant find something down there.

Moses

wrist pins will do that as well. I got a 5.0 right now that does that and it is a wrist pin.

My lame experience

I had a somewhat similar problem. My brother and I tried to swap out a transmission, (didn't happen. couldn't bolt on the other trans b/c torq convert. wasn't in all the way. Damn! broke a chunk off the bell housing and a tab off the oil pan).

When we bolted the original transmission back on, there was this wierd TICK TICK TICK TICK noise that was directly related to the engine rpm. about one tick per 1/2 second. when you hit the gas a little, it would speed up to the point where it would just be a rattle.

So, the car sat for a few weeks until we could look at it. Then, it started up just fine, and there was no ticking noise at all. I was going to drive it later that day, but about 15 minutes after driving around, the noise came back. So, the only change was the transmission. Poor engine had 230,000 miles on it. all original!!! Too bad, I was looking to putting one some more. But now it's in the middle of a complete rebuild.

So, could be a bent flexplate itself, or a AOD pump ruined due to the warped flex plate??? But, that's my transmission story, and there was a ticking involved.

what in the...

started my car this morning, and the knock is gone. completely.
and it was freezing out too. its 12 out here but its supposed to feel like 4. i figured the cold had something to do with it since it would go away when the car warmed up. hopefully its gone for good.

Moses

I've never been so lucky. You have my respect.