Hi Guys,

I had a knocking noise from my motor and when I tore it apart I've found this.

I checked the rods and the bearings are good, there's no play, but something has been hitting/smashing/bouncing around in there.

Piston doesn't seem to protrude out of the cylinder, but it's close.


It's put a crack in the #7 cylinder wall so it looks like either resleeve or new block, but I just wanted to know what could cause this becfore I rebuild and it happens again.

 

Too much timing perhaps.

 

Looks like debris went thru intake valve and got stuck in cylinder before it finally when out exhaust. Have seen carb. or air cleaner screws eat up a cylinder, head and piston. Even broke spark plug tips.
JOE

 

If it was timing, wouldn't there be damage to the valves, or a more singular pattern of marking on the pistons?

 

Looks like something metal ended up in the engine, like a screw.

 

With that kind of damage, something went through the engine. Could have been a small screw. Maybe a piece of a cotter pin.

 

I'd also have the rod checked for being bent

 

Thanks, will do.

So far I'm looking at:

Cam replacement/forced upgrade - XFI 280 $400
Cylinder Sleeve $100
Heads resurfacing $160
New Pistons 4.145" $270
Rings $100

$1030 for a motor I barely got to run. Fun fun fun. Still tossing up whether to pack it in and just put a stock ls1 in there instead.

 

100% some foreign object went thru it. Same damage on my sbc when turbo blew up

 

Awesome, thanks for the confirmation.


Well not awesome, but it's comforting to know I'm not the only one who has seen this kind of carnage.


I think I will rebuild, as I'd rather have an awesome 6.6L monster than a stock 5.3LS1, and I'd still have to fab up mounts/brackets and exhaust anyway.


Fun times ahead.

 

So many people think damage can be cheaply fixed. Even something simple like a spun bearing means a lot of repairs to fix it properly. In the end, it's cheaper to just buy a new engine. Even a stock replacement engine is cheaper than a rebuild. I picked up a catalog from the local GM dealer last week. You can buy a bare bones shortblock. Install your own camshaft, heads and intake. The bottom end is complete and that's what's going to cost the most to fix.


Every time I hurt a race engine I knew it would be a few thousand to fix it again. Biggest replacement was when I cracked the block in the mains area. $3000 for a new Dart block plus machine shop work.

 

Might be true in the USA, but here in Australia for a bone stock long motor you're still looking at $3500 for a 290hp crate motor 350.

And people think their 2nd hand sbc motors in need of a rebuild are still worth $2500, its ridiculous.

For a cracked sbc block that is only useful for a dummy fit, they still want $200-300. Crazy.

 

To be honest if the cylinder wasnt cracked, and the head valveseat wasnt damaged, a simple brush hone job in the cylinder plus a sanding cartridge roll to the head chamber and piston crown to smooth off any sharp edges, i would throw it together and run it lol

In fact i ran mine for half a year with damage to chamber and piston crown because i didnt know it ate anything motor ran so good