How to check for a cracked block

BigTone · Jun 28, 2012

Well, got the head back, no cracks, holds great pressure, it is not warped....SOOOOO he thinks that I might have a crack in the block because two of the cooper seals on the head gasket were bent. He told me to fill the block through the water jacket with boiling water and see if the level drops. It has dropped a little (less than a 1/4", more like an 1/8th) but im not sure if its equalizing out in the radiator and that is why its dropping. Anyone else know of a way to check for a crack other than looking and putting it all back together and see if it blows the gasket again? thanks guys, ~Anthony

Oldiron29 · Jun 28, 2012

Big, If the level dropped and stopped it is just balancing out. If you have water in the pan or leaking external than you have a leak or crack.
Sounds to like you had a damaged gasket installed.
oldiron29

rustred · Jun 28, 2012

you could also remove the pan and place a cardboard under the block and watch for drips. other than that you would need to isolate the block and plug the rad outlets and build a plate and gskt for the top of block so it could be checked with air pressure also. thats a big job, just for a one time thing.

John G. Hasler · Jun 28, 2012

> ...build a plate and gskt for the top of block...

Or put the head on.

rustred · Jun 28, 2012

yes that is possible, but when you pressure test the head for cracks you dont haul the block to the machine shop. they have a plate to seal it.its what ever blows your skirt up.ha, ha.

iowa steve · Jun 28, 2012

you might be able to put a light coat of spray paint where the gasket was messed up and take a fine file and go over it,if theres a crack it may show up.

rhtx55 · Jun 28, 2012

Dye penetrant and a black light.
Used a lot in aviation, any airplane mechanics handy in your area ??

Andrew Z · Jun 29, 2012

also check the top of the block for even / straightness. May needed to be cut, not too common though.

Andrew

Rumplestiltskin · Jun 29, 2012

Hi, Big Tone.

I thought the other guys would have screamed by now about pouring boiling water into a room-temperature block. I"ve always had the impression that hot water should be introduced into a cold block (and cold water into a hot block) at a trickle to avoid cracking the block via thermal stress. But I"ve never actually seen a block crack that way, so maybe I"m wrong.

Then again, if you"re putting the water in through the water jacket, maybe it is just a trickle.

Mark W. in MI

sflem849 · Jun 29, 2012

(quoted from post at 11:53:52 06/29/12) Hi, Big Tone.

I thought the other guys would have screamed by now about pouring boiling water into a room-temperature block. I"ve always had the impression that hot water should be introduced into a cold block (and cold water into a hot block) at a trickle to avoid cracking the block via thermal stress. But I"ve never actually seen a block crack that way, so maybe I"m wrong.

Then again, if you"re putting the water in through the water jacket, maybe it is just a trickle.

Mark W. in MI

Wouldn't it dissapate the heat so fast it couldn't?

How to check for a cracked block

BigTone

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Oldiron29

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rustred

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John G. Hasler

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rustred

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iowa steve

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rhtx55

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Andrew Z

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Rumplestiltskin

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sflem849

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