Ok, here's the story: I was driving over to LottaBalls house this morning, and I passed this turbo Saab. When I passed him, I shifted right past red line (about 5050 or 5100 rpm), so I was only in red line for about 1 second. Well, when I got to Derek's house, I hear clack clack clack clack. I was thinking "oh sh*t, I messed up the car." The sound isn't very fast, and it moves with the rpms. We are thinking that I either spun a bearing, messed up a rod, or maybe broke a rocker arm. I haven't driven the car since. It has almost 170,000 miles on it, so this isn't really a surprise. What do you guys think it is?

 

That definately sounds like you spun a bearing...I did the same thing on my 460 about a month ago. The problem is, I just didn't spin the bearing;.....when I spun in the bearing it caused the crankshaft to wobble and bend, which in turn caused me to brake a piston rod. So as you can see, the fun never stops when you spin a bearing.

That clacking noise was real prevalent when I turned the car off. Also, did you notice a decrease in oil pressure, mine dropped about 20 psi after I spun it. The only difference between you and me is that I spun mine on the dyno and didn't notice it with all the noise around. So I preceded to do 7 more pulls and went home, which was when I noticed the pressure drop. I then drove it for another 4 days before she gave up on me. I had no choice, I needed to get from point A to point B.

Oddly enough.. the broke motor is what caused me to buy my camaro. I guess that's the silver lining huh?? Next time I'm just going to go with a crate motor.

 

Hate to sound so stupid here, but what exactly happens when you "spin" a bearing? I've had friends who have had that happened, and fixed it, but nobody ive talked to really knows exactly what happens to cause the bearing not to work, or the difference between a "spun" and an "unspun" bearing.

 

The bearings are seated, they are not supposed to move at all. They provide a surface for the moving parts to ride on, so when the bearing unseats you have spun a bearing.

Mrs, it does sound like a spun bearing, I would pull the valve covers, just to make sure it is not a rocker arm. Did it over heat after it started making noise?

Good luck

 

just cause a motor is knocking it doesn't neccesarily mean there's a bearing spun. The bearing could just be pounded out causing excessive clearence. To "spin a bearing" is exactly that. It spins around the crank AND the rod. My 79 350 powered Merc. Capri spun 2 bearings. When i pulled the caps off, then took the bearings out, the locating tangs were missing. I looked at the rod and the respective cap and noticed the tangs were still stuck in the proper spots, but sheared off the bearing shell . The back side of both bearings surfaces weren't to pretty either. Same silver lining i guess, i bought my Camaro after that! Ahhhhh.....those good ole 305 days

 

Mr. and Mrs. lottaballs..............

that's funny, sorry but i had to say it.
:lala:

 

another possiblity is that you cracked the flexplate.

My friend did that to his 383, and it sounded just like a rod knock.

If you have rod knock, expect oil pressure to be normal at idle, and decrease as RPM increases, if you have a main bearing knock,it will be uniformly low at all RPM.

 

On my 85 Iroc I noticed a clunking sound that was faster with rpm and it turned out to be my harmonic balancer.The outer ring spun off and was flopping against the timing cover and pulley. Just something to check. Good luck

 

Hey buddy.

Before you jump to any conclusions, let me just straighten a few things up.

Knocking/Deep Hollow sound means BIG TROUBLE 99% of the time. A broken rocker arm or one that has back off alot will make a VERY similar noise.

A Clackity-Clack is usually a valvtrain problem. In other words mis-adjusted rockers ect....

Check your oil pressure gueage & see if you noticed a difference. Post back the pressure #'s also both HOT & COLD.

5100 rpm won't spin a bearing unless that motor was very weak. I wouldnt worry yet i think our SB Chev's can run a little better.

 

Ditto on the harmonic balancer.........mine did the same thing when one of the pully bolts backed out.....I thought the whole darn motor was coming apart........

 

when I spun a rod AND then later on 2 main bearing, the bearing on the rod actualy fused into one shell, then proceeded to chew 1/4 of an inch out of the crank. . . then the damn piston started to smack the head and blow little chunks off itself. . it wasn't pretty :-( good luck. . I got a 383 out of my experiences.

 

I had a spun rod brg. on my old 301. I hated that car anyway. It was a good reason for me to buy a new truck. I also broke 4 rocker arms on my engine that is in the Camaro now, all at different times. The last time it sounded just like a rod knock. In fact I was so sure thats what it was, I started taking the acc. off so I could pull the motor. My neighbor stopped over and persuaded me to pull the valve cover. Thats when I noticed the rocker arm. The bearing doesn't touch the crank. If it does, thats when you start to have problems. The oil that is between the bearing, and crank is what the crank rides on. I just tore apart a 350 in hopes of building it for a gentleman in Tennesse. I pulled off the mains, and noticed every one was spun except the rear most one. The block, crank, and all bearings are now junk.

 

I took the valve cover off, and it is not the rocker arms or pushrods. Still could be the harmonic balancer. I started it again today, and the oil pressure is normal, so I don't know if its a spun bearing.