cracked block

F

firstlight

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Joined
Mar 25, 2005
RO Number
16749
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222
mechanic removed and repaired a bent exhaust value and claimed he most do the other head at the same time. The engine now is hard to start and smokes at an idle speed, the mechanic claims NOW that the engine block may be cracked. How do you diagnose a cracked block, 2001 7.4 Crusader engine.
Does this sound right, its a friends boat and I don't want to see him get taken anymore than he already was!
 
It's tough on any engine as some cracks just dont open up until the engine is good n' warm.
I've seen a pump put into the Radiator of a car engine. Then you apply about 25 Lbs of pressure into the cooling system and check for bubbles, hissing, losing pressure etc.
Thats probably true of boat engines as well, just a different connection.

How'd you get a bent exhaust valve? What were the symptoms that caused you to go to a Mechanic? Did you winterize the whole works, manifolds and all?
 
Have to agree with the other guys, not nearly enough information. I would be really interested to know what caused the bent exhaust valve in the first place as well as the winterizing procedures that were used.

As for symptoms of a cracked block, that would totally depend on where it is cracked. Indications could include loss of compression, water in the oil, external leaking, etc. The other post is correct in that it may not be detectable until the engine is hot.

Also, in defense of your mechanic, yes, if you do one bank of valves, especially involving a near catastrophic failure such as this, you should do both heads at the same time. Whatever condition caused the one valve to fail was also present for all valves and they may have suffered damage as well.

quote:
Originally posted by firstlight

Click to expand...
 
i hate to bring bad news but i never had much luck rebuilding a top end. the extra cylinder pressure just seems to amplify ring seal issues. i doubt your block is cracked but you may find scored cylinder or pinched or broken rings. there is only one way to bend a valve on a engine and thats for the piston to contact it often with unseen damage to the ring land area, a leak down test should confirm ring seal issues
 
What i would like to see in posts are compression numbers? And vacuum numbers?
 
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