Checking for a cracked cylinder

[LWATSON]

I aquired an LB7 block today and the guy I got it from says it has a horizontal crack in one of the cylinders. He also thought it was an engine out of an 06 truck so he's not very knowlegable about dmax's. I've spun the engine over several times and cant find anything. I've heard of LBZ's with cracked cylinders but not LB7's. Whats the best way to check this thing out? I really think he probably had a blown head gasket or something and didn't know.

 

[Chevy1925]

pull the heads, disassemble them, hot tank them, and go over them with a fine tooth comb.

 

[sickdiesel]

mag test it

 

[Chevy1925]

mag test it

you cant mag test aluminum.

 

[Turbo Performance]

you cant mag test aluminum.

Since when are the cylinders aluminum? Think he's talking block and you're talking cylinder heads.

 

[LWATSON]

Yes, he claimes a crack in a cylinder. I dont want spend allot of money confirming his theory but it just seems unlikely an LB7 would have a cracked cylinder. I'm leaning towards, he didn't really know what was wrong so this is what he told the owner of the truck. If most of you guys feel the same way as I do I'll take a chance and have someone check it out. But I would really like to feel comfortable that I've checked it best I can before I do send it to someone.

 

[TeaBagger2006]

I highly doubt it's the block... Mag test the block

 

[Chevy1925]

Since when are the cylinders aluminum? Think he's talking block and you're talking cylinder heads.

Lol fuuuuudge your right. Dunno why i was stuck on thinkin he was talkin about heads.

My bad sickdiesel. Mag test would be the way to go

 

[LWATSON]

I guess I'll clean it up and look it over good then take it to get checked.

 

[hondarider552]

If anyone hasnt said to Mag it, I would Mag it.

 

[LWATSON]

Please excuse my ignorance but can I buy a kit and check it myself or am I better off to hire someone to do this?

 

[hondarider552]

I paid $130 to mag the crank and block at my machine shop.

 

[Turbo Performance]

Please excuse my ignorance but can I buy a kit and check it myself or am I better off to hire someone to do this?

You'd pay way more for a mag kit than to have a machine shop do it for you. You could always do a penetrate dye to show any surface cracks but I don't think it will be as accurate as a mag test.

 

[whytry]

I would get the machine shop to presure check the block that's the only way to know 100% that there is no cracks

 

[LWATSON]

Thanks for the advice guys I'm going to tare it down and get it to a shop this week. Wish me luck!