Cracked block or headgasket?
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Cruising
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Cracked block or headgasket?
I disassembled my 2003 z06 and the head gasket and block look okay yet white smoke is coming out of the exhaust and there is coolant in the oil. Is there a common location where these blocks crack that I could check?
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From: Guinness Its whats for B'fast JAWGA
CI 3-4-5-9 Veteran
overheating, bad antifreeze can damage the block.Could be a head gasket or the head bolt holes can crack in the block if the threrads were not cleaned out before reinstllation or a head stud was over tightened into the block
Last edited by 93Polo; Nov 1, 2023 at 12:02 PM.
Melting Slicks
Joined: Sep 2011
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From: Appleton WI
It could be a cracked head. Did you pull both sides already? If not, why did you pull the side you did? Look at the top of the pistons. The cylinder with the leak will be clean compared to the rest,
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Cruising
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Single owner with 23,000 miles. Daily driven during those miles but never taken to the track.I do not know the antifreeze history. I have it apart and have been inspecting the block and gasket however I cant find the exact cause.
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Melting Slicks
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You were seeing white smoke so you pulled both heads and can't find a crack. That's not exceptionally unusual, the crack(s) can be almost invisible to the naked eye. Magnaflux used to be THE process to find cracks, I don't know how it's commonly done today. Back in the day the components in question went to the machine shop and they had the Magnaflux equipment.
93Polo suggested the head bolt holes could crack IN THE BLOCK so if you have the heads off now you might as well check there. You don't know the history and it's a known failure point.
No, you can't do a compression or leak down with the heads off. You CAN look at all eight pistons. Does one of them look clean compared to the others? That is the one that has coolant entering. That coolant turns to steam when the pressure drops during the suck and blow revolutions of a four cycle engine and that steam will probably clean any deposits off the face of the piston.
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You didn't quote the posts you replied to so I'm guessing a little here.
You were seeing white smoke so you pulled both heads and can't find a crack. That's not exceptionally unusual, the crack(s) can be almost invisible to the naked eye. Magnaflux used to be THE process to find cracks, I don't know how it's commonly done today. Back in the day the components in question went to the machine shop and they had the Magnaflux equipment.
93Polo suggested the head bolt holes could crack IN THE BLOCK so if you have the heads off now you might as well check there. You don't know the history and it's a known failure point.
No, you can't do a compression or leak down with the heads off. You CAN look at all eight pistons. Does one of them look clean compared to the others? That is the one that has coolant entering. That coolant turns to steam when the pressure drops during the suck and blow revolutions of a four cycle engine and that steam will probably clean any deposits off the face of the piston.
You were seeing white smoke so you pulled both heads and can't find a crack. That's not exceptionally unusual, the crack(s) can be almost invisible to the naked eye. Magnaflux used to be THE process to find cracks, I don't know how it's commonly done today. Back in the day the components in question went to the machine shop and they had the Magnaflux equipment.
93Polo suggested the head bolt holes could crack IN THE BLOCK so if you have the heads off now you might as well check there. You don't know the history and it's a known failure point.
No, you can't do a compression or leak down with the heads off. You CAN look at all eight pistons. Does one of them look clean compared to the others? That is the one that has coolant entering. That coolant turns to steam when the pressure drops during the suck and blow revolutions of a four cycle engine and that steam will probably clean any deposits off the face of the piston.
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From: Guinness Its whats for B'fast JAWGA
CI 3-4-5-9 Veteran
If the heads have not been off recently, chances are low of this. But, yes if there is gunk in the head bolt holes and you torque it down, the block can crack around the thread causing coolant to get where it doesn't belong.
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From: Guinness Its whats for B'fast JAWGA
CI 3-4-5-9 Veteran
Odd, with the heads off, I'd have a machinist check the heads over well, pressure test, look at guides, valve stem seals, and deck them for cleanup. Verify a valve isn't bent. A valve can have a slight bend and seal for a while, granted if a valve was bent you should see marks on a piston.
Melting Slicks
Joined: Sep 2011
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From: Appleton WI
I think we need more of the story. What made you start to investigate? What events led up to the identifying the white smoke and coolant in the oil? What kind of exhaust do you have (stock or aftermarket) Was the white smoke from one or both sides? Even with the stock H pipe, one side should be significantly heavier vs the other. Was there any engine work, track day, driven spirited? Given the fact that you're not seeing one cylinder much cleaner than the others, is confusing and I'm wondering if the white smoke is totally separate from the coolant in oil. The white smoke might not be relevant as it could be moisture in the exhaust and was identified after finding coolant in the oil. If this were the case, the issue could be further down in the block such as a water jacket leak. Maybe test the coolant to see if there is evidence of exhaust leaking into the coolant.
Pro
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From: Nova Scotia Canada
You were seeing white smoke so you pulled both heads and can't find a crack. That's not exceptionally unusual, the crack(s) can be almost invisible to the naked eye. Magnaflux used to be THE process to find cracks, I don't know how it's commonly done today. Back in the day the components in question went to the machine shop and they had the Magnaflux equipment.
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Like 93 polo said. Look at the chambers and spark plugs of all cylinders. Look for... One of these things is not like the others....
Find that one odd one and you found the cylinder/area that was leaking. Now that it is apart and you found the offending cylinder being different, look closely for a crack in the head/block(try a magnifier and a bright light) or bad gasket (usually between cylinders).
Nonferrous/aluminum parts are checked for cracks with penetrant. Two common methods, either visual penetrant or Florescent (black light) The process is only as good as the prep, needs to be clean. In a pinch if the area is dry you can use WD-40 as a penetrant as its capillary action will seep into a crack. The capillary action is the foundation of penetrant inspection for cracks on nonferrous parts.
Find that one odd one and you found the cylinder/area that was leaking. Now that it is apart and you found the offending cylinder being different, look closely for a crack in the head/block(try a magnifier and a bright light) or bad gasket (usually between cylinders).
Nonferrous/aluminum parts are checked for cracks with penetrant. Two common methods, either visual penetrant or Florescent (black light) The process is only as good as the prep, needs to be clean. In a pinch if the area is dry you can use WD-40 as a penetrant as its capillary action will seep into a crack. The capillary action is the foundation of penetrant inspection for cracks on nonferrous parts.
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Cruising
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I think we need more of the story. What made you start to investigate? What events led up to the identifying the white smoke and coolant in the oil? What kind of exhaust do you have (stock or aftermarket) Was the white smoke from one or both sides? Even with the stock H pipe, one side should be significantly heavier vs the other. Was there any engine work, track day, driven spirited? Given the fact that you're not seeing one cylinder much cleaner than the others, is confusing and I'm wondering if the white smoke is totally separate from the coolant in oil. The white smoke might not be relevant as it could be moisture in the exhaust and was identified after finding coolant in the oil. If this were the case, the issue could be further down in the block such as a water jacket leak. Maybe test the coolant to see if there is evidence of exhaust leaking into the coolant.
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