Could this be Rod Knock?? - Honda Prelude Forum

prelude styl · 10-27-2003, 01:33 AM

I did a search and am not really sure what this is so I decided I'd post.

I went to the drag strip the other day, ran a bunch, car seemed not to be running as fast as it should, but nothing terribly wrong. Still drove fine, idled like it usually does (very rough, but it's been like that since I got it.. dunno wtf it is).
After we left the track and were headed to the fwy I noticed a very loud buzz/rattle (like a rattle that you'd hear from a sub rattling the interior.. but that noise constantly) above 3300rpms in every gear. As soon at I hit 3500rpm it gets really loud but you can't hear crap till then. At first I thought I had just rattled something loose in my dash (the road to the track is a rough dirt road) but when I pulled over with my friends and revved up the engine for them when they were looking under the hood, they said it was coming right from the motor. Thier first thought was I broke a valvespring, but today I took off the valve cover and inspected everything, nothing looks out of the ordinary. So... what do you guys think? It drives fine around town, and I don't really hear anything till after 3300.. then it's all of a sudden real loud constant rattle.\

Help

cantdrive55 · 10-27-2003, 01:41 AM

My guess is a broken header bracket...or like mine, one of the bolts backed out and is causing a nasty rattling. If it were rod knock, you *SHOULD* her it at idle.

prelude styl · 10-27-2003, 02:11 AM

yea there's no new noises at idle at all.. but it's veeery predominant above 3300. As for the header bracket, I know that's not it cause my bracket isn't there(long story), so there's nothing for it to vibrate against.

bsi · 10-27-2003, 08:11 AM

can you feel it in the pedal.... right before my last engine went you feel that something was seriously wrong when you hit the gas.

prelude styl · 10-27-2003, 12:03 PM

no I can't feel any strong vibrations in the pedal.

The more I listen to the motor, the more I hear it knocking at idle. Are there any other symptoms I can look for, anyone know? Thanks.

bsi · 10-27-2003, 01:49 PM

Quote:

Originally posted by prelude styl
[B. Are there any other symptoms I can look for, anyone know? Thanks. [/B]

check engine light?

marshdoggg · 10-27-2003, 02:32 PM

Quote:

Originally posted by prelude styl
no I can't feel any strong vibrations in the pedal.

The more I listen to the motor, the more I hear it knocking at idle. Are there any other symptoms I can look for, anyone know? Thanks.

ok 2 things here. 1, the more you listen to any motor, the more knocking you hear. your brain just sorta finds it.
2. a lot of times, you can only hear the knocking at certain rpms, not at idle. i never heard mine at idle, but at around 2300 you could really hear it. so dont just listen for it at idle.
and it doesnt sound how you desribed it. knock is the best description i know, it sounds like its knocking on the inside of the motor.
marsh

prelude styl · 10-27-2003, 02:34 PM

there's no CEL... that woulda been obvious lol. I'm not stupid. So obviously it's not bad enough that the knock sensor would pick it up.. but it's there. I just don't want to keep driving it if I'm gonna blow a hole in my block from throwing a rod when the bearing goes.

prelude styl · 10-27-2003, 03:04 PM

regardless of if it's rod knock or not.. I need help figuring out what it is. There's nothing wrong with the valvetrain, I took off the valve cover and checked it all out, looks fine. I listened to the inside of the motor (using a breaker bar) and the knocking sounds louder in the head that in the block, but still very audible in the block.

[SUB[EX] · 10-27-2003, 04:11 PM

It sounds really bad when your Balancer belt goes. You might as well just remove it.

A rod knock will sound like someone is hammering the bottom of your car. Its a discusting sound. You wouldnt wana start your car and let it idle if it was really knocking.

prelude styl · 10-27-2003, 04:37 PM

I removed my balance shaft belt a long time ago.

bogus · 10-27-2003, 04:48 PM

I would start with the balance shaft.

if it was a rod knock, especially that loud, it woulda blown by now... considering the drag racing.

if might be something with a stuck valve or something has gotten sucked into a combustion chamber.

several years ago, at my local honda/acura dealer, they had sold a brand new Integra GSR Type R. It had little or no miles on it. The new owner got about 5 miles down the road when it died. They towed it back, and put a new motor in it.

The diagnosis was interesting... one of those sodium filled 2 piece valves decided it wanted to become 2 pieces again. And the head of the valve separated and started to mate with the piston.

The end result? 1 toasted motor.

achemze · 05-24-2005, 12:58 PM

every find out what this was?