Rescuing the Build from Hell - bore crack?
Thread Starter
Le Mans Master
Joined: Jun 2004
Posts: 6,231
Likes: 65
From: Seattle WA
St. Jude Donor '14
Rescuing the Build from Hell - bore crack?
Does this look like a crack in the bore to you? I've never actually seen one. Figured I'd ask before taking the dyepen route...
Last edited by billla; Aug 21, 2009 at 06:51 PM.
Thread Starter
Le Mans Master
Joined: Jun 2004
Posts: 6,231
Likes: 65
From: Seattle WA
St. Jude Donor '14
No other cylinders show any pattern like that - and I've never seen that pattern and can't think of any other cause. The engine evidently overheated during break-in. No indications of oil in the coolant.
I figure I have to dye test it - but thought I'd take advantage of the expertise here as I can't get to it until Sunday.
I figure I have to dye test it - but thought I'd take advantage of the expertise here as I can't get to it until Sunday.
Race Director
Joined: May 2006
Posts: 16,528
Likes: 53
From: Dayton, Ohio
I'm no expert but I have seen a couple cracked cylinders at the top before. The pattern above and below doesn't look familiar. It sorta looks like the piston could have rocked over and touched. I can see the normal rust on top of the block why isnt it showing in the center of the pattern where I would think the crack is suspected of being ?
Burning Brakes
Joined: Jan 2007
Posts: 1,057
Likes: 4
From: Concord Calif
Does this look like a crack in the bore to you? I've never actually seen one. Figured I'd ask before taking the dyepen route...
http://farm4.static.flickr.com/3507/...b99050d9e8.jpg
http://farm4.static.flickr.com/3507/...b99050d9e8.jpg
http://farm4.static.flickr.com/3507/...b99050d9e8.jpg
http://farm4.static.flickr.com/3507/...b99050d9e8.jpg
Wow you never seem a cracked bore! Anyway it could be but probaly not as most bores crack up and down and not around the bore unless it has been way over bored. That looks more like some coolent sat there for a short time, at lease from the pictures it does. Was there any coolent in the bore when the heads came off? Short of a mag and or presure test you could try some very fine emery cloth on it, that will leave a line where the crack is if it is there, the sanded metal pieces will be attrated to the crack area and leave a line of sanded metal standing up just like a mag would do as sanding will magatize the metal some. Yea my spelling sucks
Thread Starter
Le Mans Master
Joined: Jun 2004
Posts: 6,231
Likes: 65
From: Seattle WA
St. Jude Donor '14
Your spelling is fine, Manuel 
I never have seen one - either it's caught at the shop after teardown and I get "the call" or the engine is in pieces in another and more obvious way 
No coolant in the bore, no oil in the coolant. The overbore was .040 based on the stamping on the piston. The engine has about 40 minutes on it - so it could just be a start-up scuff but it's sure an odd mark. Could it be a scuff from the overheat?
I never have seen one - either it's caught at the shop after teardown and I get "the call" or the engine is in pieces in another and more obvious way No coolant in the bore, no oil in the coolant. The overbore was .040 based on the stamping on the piston. The engine has about 40 minutes on it - so it could just be a start-up scuff but it's sure an odd mark. Could it be a scuff from the overheat?
Burning Brakes
Joined: Jan 2007
Posts: 1,057
Likes: 4
From: Concord Calif
Your spelling is fine, Manuel I never have seen one - either it's caught at the shop after teardown and I get "the call" or the engine is in pieces in another and more obvious way
No coolant in the bore, no oil in the coolant. The overbore was .040 based on the stamping on the piston. The engine has about 40 minutes on it - so it could just be a start-up scuff but it's sure an odd mark. Could it be a scuff from the overheat?
I never have seen one - either it's caught at the shop after teardown and I get "the call" or the engine is in pieces in another and more obvious way No coolant in the bore, no oil in the coolant. The overbore was .040 based on the stamping on the piston. The engine has about 40 minutes on it - so it could just be a start-up scuff but it's sure an odd mark. Could it be a scuff from the overheat?
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Brett Foote
Team Owner
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From: Crossville TN
Can you feel any significant difference in dragging your fingernail across it [compared to doing the same thing in another area of the bore]? There is some surface imperfection there, but it may just be some minor scuffing damage that the hone almost completely cleaned-up. It would be good to do a proper dye/penetrant check to see if there is any depth to that area. A heat crack oriented that way in the bore would be rather unusual....but not impossible. Better be safe now. A good welder/machinist can still save it, if necessary.
Burning Brakes
Joined: Jan 2007
Posts: 1,057
Likes: 4
From: Concord Calif
Can you feel any significant difference in dragging your fingernail across it [compared to doing the same thing in another area of the bore]? There is some surface imperfection there, but it may just be some minor scuffing damage that the hone almost completely cleaned-up. It would be good to do a proper dye/penetrant check to see if there is any depth to that area. A heat crack oriented that way in the bore would be rather unusual....but not impossible. Better be safe now. A good welder/machinist can still save it, if necessary.
I know your just trying to help but be carefull sugtgesting things to do that are just not going to work and just plain don't work.
point being, you do not I mean DO NOT EVER think of welding a cylinder bore for any reason, the repair is to sleave the bore if it has a crack.
Thread Starter
Le Mans Master
Joined: Jun 2004
Posts: 6,231
Likes: 65
From: Seattle WA
St. Jude Donor '14
What a sweet guy. This isn't my engine - it was won by a guy in a raffle for the Ronald McDonald House Charities. I'll pass on your sentiment to all those kids with scars on their heads and tubes up their noses the next time I'm there volunteering
Last edited by billla; Aug 21, 2009 at 12:15 AM.
Thread Starter
Le Mans Master
Joined: Jun 2004
Posts: 6,231
Likes: 65
From: Seattle WA
St. Jude Donor '14
Update - my machine shop is going to loan a torque plate and water pump fitting to do a pressure test of the block where it sits. He doesn't feel it's a crack, but also doesn't' recall seeing a mark like that before - and he runs a Level 4 shop :/
Thread Starter
Le Mans Master
Joined: Jun 2004
Posts: 6,231
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From: Seattle WA
St. Jude Donor '14
Le Mans Master
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From: Gladstone MO
C3 of Year Finalist (appearance mods) 2019
I'd sure hit it with a dye penetrant- just to be sure. Most cracked cylinders I've seen have been vertical in the bore. .040 is not a huge overbore for a SBC.