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Old 09-18-2010, 01:36 PM   #1
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How to tell if block is cracked?

I recently bought a chevy 350 engine for my car that was partially assembled. I got the engine for only $400. The block #'s are 3970010.
I would like to know if the engine is cracked as this was really good price. A friend of mine told me to do a stand test and run the engine before putting it in the car to see if it smokes from the exhaust manifolds or not. So, my question is: will the engine always smoke if the block is cracked. I know a head gasket has the same symptoms and I was told that all gaskets have been changed. Thanks for anyone that replies. Also, I was thinking about getting a pypes tranvers voilator muffler for my car and wanted to know how it compares to a glasspack. thanks again.
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Old 09-18-2010, 02:21 PM   #2
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Re: How to tell if block is cracked?

No it will not always smoke it depends on where its cracked. It may leak outside the block it may leak coolant into the oil pan or it may not leak at all depending on where the damage is and how bad. Also even if the block is good the heads may be cracked or a head gasket may have been installed incorrectly so just because you saw smoke dosnt mean the blocks cracked. The only way to truely know if it has issues is to take it to a machine shop and have it magnafluxed. However practically speaking just doing things like a compression test, pressurize the cooling system, test run the motor and check the oil things of that nature will be a good enough for the most part.
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Old 09-18-2010, 02:51 PM   #3
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Re: How to tell if block is cracked?

Typically when a block is cracked, it's very evident. A cracked block is most common from freezing in the winter when the coolant isn't strong enough and freezes. Ice has amazing forces that can split metal. The most common place a block will crack is the cylinder walls. If it's cracked from overuse, there will be very physical damage. Even an engine that throws a rod can be repaired by sleeving a cylinder unless it's broken a big chunk of of the block itself.

Without disassembling an engine to examine the cylinder walls, a cracked cylinder wall may be hard to detect. It may not expand enough to cause a leak until the engine gets hot. There are any number of places coolant can leak. Coolant smoke out the exhaust could be a cracked head or a bad head gasket. A bad head gasket could indicate a warped head or the deck of the block needs to be machined.

Buying a used engine that's in need of repair isn't much of a deal unless it's free. Even then, the cost of repairs could exceed the cost of a replacement engine.
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Old 09-18-2010, 07:59 PM   #4
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Re: How to tell if block is cracked?

if I am leaking oil out a whole looks like bottom of transmission, what think could be leaking? http://www.youtube.com/watch?v=PNH7uJ-C9YQ
Its coming out the whole in begigng of vid with the little bit of oil near it.
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Old 09-18-2010, 08:06 PM   #5
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Re: How to tell if block is cracked?

Quote:
Originally Posted by thunder69n View Post
if I am leaking oil out a whole looks like bottom of transmission, what think could be leaking? http://www.youtube.com/watch?v=PNH7uJ-C9YQ
Its coming out the whole in begigng of vid with the little bit of oil near it.
May want to start your own thread as this question really dosnt belong here in someone elses unrelated thread but its probably your rear main seal, back of your intake manifold, or at the fitting for your oil pressure gauge.
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Old 09-19-2010, 07:38 AM   #6
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Re: How to tell if block is cracked?

Quote:
Originally Posted by MikeSammy View Post
I recently bought a chevy 350 engine for my car that was partially assembled. I got the engine for only $400. The block #'s are 3970010.
I would like to know if the engine is cracked as this was really good price. A friend of mine told me to do a stand test and run the engine before putting it in the car to see if it smokes from the exhaust manifolds or not. So, my question is: will the engine always smoke if the block is cracked. I know a head gasket has the same symptoms and I was told that all gaskets have been changed. Thanks for anyone that replies. Also, I was thinking about getting a pypes tranvers voilator muffler for my car and wanted to know how it compares to a glasspack. thanks again.
Those blocks aren't very crack-prone. Most of the 3970010 cracks tend to be in the main webs of the 4-bolt blocks. 2-bolt 3970010s almost never crack, unless it's just that there was no ethylene-glycol in the water one winter.
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Old 08-09-2012, 03:05 PM   #7
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Re: How to tell if block is cracked?

i have a 1999 camaro ss with a 6.0 in it idk if it has a cracked block or if it may have bad gas in it my car started smoking out of the exh and does it when the car warms up but not when its cold could it be bad gas it didnt start doing this till i got gas please help?/
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Old 08-09-2012, 03:05 PM
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