I swapped a LS1/T56 in my thirdgen a couple years ago, and I've had a horrible oil leak since day one. It's a project car that's not done, as I've had very little time in the past year or two to work on it. With the engine running it would leak out about half a quart in about 30 minutes. It was dripping out between the block and bellhousing, as well as above the oil filter.

Fast forward to a couple months ago, when I got time to work on it, I tried a few things. First, the rear corner tab on the oil pan was broken off, so I put a new pan on. Still leaked. Next, I changed the rear cover gasket and rear main seal...twice...still leaked. Replaced oil galley plug in block just above the filter...still leaked.

As you can imagine, I was highly pissed at this point. I was lying under the car one day, with the trans out, just staring at the back of the engine with an led flashlight (rear cover was off), and there it was. Son of a bitch, there's the leak. My camera sucks, but here you go.







I don't know how well you can see it, I circled where it is, but the block is cracked...all the way through. I never could see it because with the rear cover on, the crack is at the bottom of the gap. That, my friends, is a kick in the nuts. Always be leary of junkyard pullouts. Time for a new block .

 

man that sucks....

 

Sad story. Thanks for sharing your pain. It might help someone in the future.

Was the ear broken off the oil pan near the crack in the block?

 

i think you have to apply gm engine sealant(equivilent) to the four corners of the oil pan.

 

Sort of. Odd thing is, there is no sign of impact anywhere near the crack.

I don't think any kind of sealant will help a 3" crack in the block...not to mention a crack right where a main oil pressure pocket is.

 

should have looked more closely

 

That sux so bad dude. Good catch though. 6.0 Iron block time !!

 

I would just jb weld it and see how long it lasts. Its worth a shot.

 

Damn, that sucks man. You could always see if someone could repair that. Drill it out and fill it. What harm could it do lol. Then again, depending on the price, it might be better to just find a shortblock.

 

Easy to say that, but in reality most of us here wouldn't have caught it either.

When I picked mine up at the junkyard, it had the trans still attached and was bolted to a shipping pallet and had thousands of miles worth of gunk stuck to it...no way I could have inspected the underside for a crack like fast377 had.

 

Exactly...and when the rear cover is bolted on, oil seeps out from the gap between the cover and block. And since the crack is in the corner, it made it impossible to see lying on my back under the car (until I really started examining things).

Due to the location, this can't be fixed. The oil coming to and from the filter goes right through the block where this crack is. As soon as it builds pressure, oil gets pushed out through the crack.

This gave me an excuse to go with forged internals on a new build. I just need to get a good block for cheap. Machine work gets pricey on these blocks.

 

guys at the junkyard are butchers, they don't give a ****.