block crack in water jacket

[afofsupra]

I just picked up another supra with an unassembled machined motor I was hoping to use.
Unfortunately it has a crack in the #2 piston water jacket where the casting divider meets the piston wall, the side with 2 water jacket holes. This is on the deck.
:1zhelp:
Is this block trash? Would it threaten the integrity of the head gasket on a NA motor or cause piston ring problems (like flex in the combustion chamber)?
Can't believe his machine shop decked & cleaned this block and took his money knowing the block has a water jacket crack. They are either dishonest or don't care.

 

[Nick M]

Clear pic? It might not be any good if you are close to the bore. It might be fixable too.

 

[IJ.]

Pretty common on early blocks, a good macro pic with flash please?

 

[afofsupra]

Yeah guys, I'll be back over there with my decent cam & macro lenses.

 

[starscream5000]

You plan on doing anthing other that a stock setup?

 

[afofsupra]

No, just daily beater for now. Stock NA with stock toyota composite head gasket & head bolts, main & rod bearings.

 

[WhtMa71]

IJ, is there anyway that a crack like that can be welded and then the deck resurfaced again?

 

[starscream5000]

No, just daily beater for now. Stock NA with stock toyota composite head gasket & head bolts, main & rod bearings.

What worries me is the crack to the bolt hole more that the other one. If it is deemed reusable (and I don't know this for sure), then your best be would be to use ARP head studs instead of head bolts as the bolt hole will not have as much stress on it as a bolt being torqued down into it.

 

[afofsupra]

Good point starscream. I didn't see the bolt hole --> water jacket hole cracks before, after researching on here, it came up a few times. "Dealing with the Common 7M Block Crack" http://www.supramania.com/forums/showthread.php?t=2393 thread prompted me to check the deck this morning and viola! 3 definite cracks, 1 definite start and the others are suspect.

 

[GrimJack]

I think 'common' isn't quite accurate on that thread title. Sure, it happens. However, if I had to rate the likelihood of Supra problems, I'd say it's something like this:

BHG - chance of this happening in the life of your car: 99.9%
Rod Knock - chance of this happening in the life of your car: 20% (+10% for every time you fill up with gas and neglect to check the oil)
Block crack - chance of this happening in the life of your car: 5%

 

[IJ.]

Actually on pre 89 blocks those cracks are common

My bud's 28 thousand mile 87 has em.....

The one in the web isn't a problem just looks bad.

The Bolt hole one is a concern if it was going to be a performance application, I'd carefully countersing ALL of the holes in the deck (I radius all of the sharp edges with a dremel to prevent this sort of thing)

I'd then buy a set of ARP Studs and after cleaning the holes spotlessly and washing them with paint thinner and drying them with compressed air I'd use Blue loctite (243) and glue the studs in and let them set before going further.
(this is how I did my bud's motor)

As for welding it yep if you can find someone that's good but be ready to do a LOT of machine work once it's all done (block needs to be furnace heated first)

 

[afofsupra]

Yippee!! Thanks IJ!!

This supra was built in 86 but I don't know what year supra the new motor is from. We're batting 1000 on this.
86.5 supra, rod knock (run with no oil) so we get an ebay jdm cressida, tear that down and it has spun bearings, get another motor that has been machined waiting to be assembled, complete with new toyota gaskets, bearings, rings & assembled head.....this one has a cracked block!!! Argh....lol. That car's original motor has 4 blown pistons!!! 4 na motors, none of em run, lol. Machine shops must love 7m's!!

Thanks for all the input!! I think I've caught the mkIII bug, maybe it's time for a na --> turbo conversion for the parts car!!!