When you click on links to various merchants on this site and make a purchase, this can result in this site earning a commission. Affiliate programs and affiliations include, but are not limited to, the eBay Partner Network.
Just started putting together this LQ4 and we noticed there was this hairline crack between water passages.
Block was magnafulxed and the machine shop said it was fine.
Not sure what to do now. Dad wants to just put some sealant in that area and run it.
Motor ran fine before and had no signs of any leaks.
Anyone run an engine with a crack like this and have no issues? Just a 10.5:1 build with rec ports and a nice cam.
I can see a crack, that block has went through a winter with a lack of antifreeze. If it didn't leak before, but had stock, untouched head gaskets - it might leak when reassembled with new gaskets. I wouldn't run it, myself. Too much of a hassle if there is a problem.
If you're talking about where it looks like the sleeve has detached from the casting, then yeah, that's pretty much toast. The 2 sides of it look like they're not even in the same plane anymore.
I don't think I'd run it. Although, if you can have the shop mag it again while you watch, and it's OK, then maybe. Otherwise, if it's bad, I'd expect them to cut you some slack on buying and/or prepping another block, for missing a defect like that and taking your money for all the other machine work.
I’d make sure it’s a crack, and if it is.. how far does it really go? There is a 2 part spray can of penetrating dye most machine shops keep on hand for looking at cracks like this one.
At least you caught it while still on the stand. Sucks x2 when you’ve wasted several hours of labor only to find out
2) I've got a serious question for all the smart guys out there: Why WOULDN'T this work? Have you ever seen an engine with "floating cylinders," or an "open deck?"
Ex:
MANY manufacturers have made it work over the years. Why won't it work now, on an LS engine? Has anyone ever TRIED running a block that was cracked in such a way?
Might work if the block was decked flat. Obviously it's not now, and the part that's depressed, is where the fire ring needs to go but won't have full crush.
But it's also possible that it's cracked somewhere else too, like down at the bottom, to allow that much misalignment.
So yeah, a block that's designed from the ground up for the sleeves to float at the top, like if the webbing at the bottom was built strong enough to hold the sleeves in place sure; but a block that isn't, and is broken, ... maybe not so much.
Thermals. It’s designed as a unit that relies on the entire deck surface to keep the cylinders from (A) moving laterally when it reaches operating temp, and (B) from moving longitudinally when it reaches operating temp. The longitudinal movement at the crack will lift the headgasket enough to leak. The cylinder sleeve will be much hotter at the gasket than the block surface at the gasket, so that’s where the thermal disagreements will lift the headgasket.
The lateral movement won’t have the same effect on the headgasket as the longitudinal movement will, regarding coolant leakage. The longitudinal movement of the cylinder….it actually raising up above the deck surface…will cause the leak.
The above pictured block with floating cylinders is designed from step one to overcome longitudinal and lateral movement by adding enough material at the south end of the actual sleeve. It’s a very robust design with lots of meat to locate the cylinder properly. There’s simply enough material around the sleeve as well to control growth in both directions.
Why mag a dirty block? It's obvious that there's residue in the area in question.
An LQ 4 block doesn't have sleeves unless it has been repaired before.
6 Common C5 Corvette Failures and What's Involved In Repairing Them
Slideshow: From wobbling harmonic balancers to failed EBCMs, these are the issues that define long-term C5 ownership and what repairs typically involve.
Retro Modern Bandit Pontiac Trans AM Comes With Burt Reynolds' Autograph
Slideshow: A modern Camaro transformed into a retro icon, this limited-run "Bandit" build blends nostalgia with brute force in a way few revivals manage.
Top 10 Greatest Cadillac V Series Performance Models Ever, Ranked
Slideshow: Cadillac didn't just crash the high-performance luxury vehicle party, it showed up loud, supercharged, and occasionally a little unhinged...
Coachbuilt N2A Anteros Is an LS2-Powered C6 Corvette In Italian Clothes
Slideshow: A one-off sports car that looks like a vintage Italian exotic-but hides a C6 Corvette underneath-just sold for the price of a new mid-engine Corvette.
LQ4 Water jacket crack. HELP....... 
