Austin95

iTrader: (22)

Here's the video of a car we just bought,'98 Formula M6. Runs and drives but makes this horrible *** noise. I'm thinking it's a spun rod bearing, but I'm sure some of the more veteran guys could chime in. Oil pressure is still at 40 upon start up and the motor has 133k on it. Let me know what you think.

fastassls1maro

iTrader: (22)

yikes that doesnt sound good at all. I would not be driving it around to prevent any further damage. Its really hard to tell from the video whether its in the top end or the bottom end. I would pull the valve covers off first and see if all the rockers are still intact and make sure none of the pushrods are loose or broken. If all that checks out ok i would suspect its in the bottom end somewhere. You could also try draining the oil into a paint strainer and see if there is any particles in it

Austin95

iTrader: (22)

Haha yes, I agree. I'd be upset if it was my car. I bought it this way and am in the middle of pulling it out now. Just trying to see if anyone would know what the sound is.

ls1 1990 VN

Piston!

JOHNNY59

iTrader: (398)

wow!!!!

mkvamso

iTrader: (2)

Piston/rod

blackbirdls1

iTrader: (5)

Yea I wouldn't run it at all

Camaro9969

iTrader: (12)

Holy hell you bought it like that? Guessing you got a deal haha. Id say rod bearing but even those dont sound that bad lol keep us posted what you find

LS1MCSS

iTrader: (18)

Did anybody notice that it quit when he revved it up so the rotating assembly had a load on it? Sounds strange for a rod bearing. My guess is something else.

high impact

iTrader: (5)

I am tuned in to see what this is. It sure doesn't sound like a rod bearing...

JOHNNY59

iTrader: (398)

its my son's car and he did get a hell of a deal! Kook's headers and catted y-pipe, Maganflow catback,new monster clutch and flywheel, Tick clutch cylinder. body and interior are perfect. I did notice that the noise decreases as the rpm's rise as stated by LMIMCSS. what should we look for when the motor is taken apart, rod or main bearings, pistons?

Camaro9969

iTrader: (12)

Chances are soon as you get into the motor will be pretty easy to find. Pull the heads then the pan. Slap a cheap lq4 in there and a different cam and get it back out there.

HCI2000SS

iTrader: (2)

Is it louder towards the bottom of the motor or top? This sounds almost exactly like my LS1 did when I found out it spun a rod bearing, and trashed everything except the block and heads. Sorry man, but that's what it sounds like to me If it is coming from the bottom of the motor then that is almost certain that's what it is

Austin95

iTrader: (22)

Ya I bought it to part out, but its too nice. So I'm going to try and sell it as a roller first.

It sounds louder towards the bottom. I'm thinking its a rod bearing as well. Hopefully that's what it is and I can just have the crank turned and toss in some undersized bearings and call it a day. Haha, but my luck it will probably be a busted piston in cylinder 7. I also found a ton of metal shavings on the drain plug magnet when I drained the oil. As in it looked like someone threw a glob of anti-seize on the plug haha.

By the way, got the motor on the stand and I'll be tearing into it in the next day or two, I'll keep you guys posted

Austin95

iTrader: (22)

Here's the diagnosis from cylinder 6:




So I take it I can't reuse rod number 6 without getting it resized right?

Camaro9969

iTrader: (12)

Ya figured it was a rod bearing. I would just find another stock rod wont cost you hardly anything. Have the rod checked out see how it looks you may be able to reuse it but i wouldnt.

high impact

iTrader: (5)

Pure ugliness. Now get it back together. ;-)

JOHNNY59

iTrader: (398)

this is want happens when the oil is not changed regularly!