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0 compression in 1 cylinder

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bainmogo

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"I have a Carver 300 with 1 ne

"I have a Carver 300 with 1 new 305 CID and one older 305. The older 305 has 1 cylinder that is 0 compression. Is it safe to operate this engine? Is there anything I can do temporarily? I need to get my boat home, and the trip is 140 miles. I can run on 1 engine.
Thanks for help."
 
"Is it safe.....depends upon w

"Is it safe.....depends upon where the 'leak' is. A leakdown test will tell you for sure. Overall, I'd say its not a good idea. I'd make plans for the slow trip if you need tomove it now...

I doubt there any temp fix that's worth the effort. Until you get the results of the leakdown test, it's only a guess."
 
Hot air comes through the PCV

Hot air comes through the PCV valve when removed. The engine had good compression then for some reason lost all in one cylinder?
 
"Assuming the engine was runni

"Assuming the engine was running & warm when you pulled the PCV valve and the air exiting the PCV valve pulsed with the bad cylinder, I'd say you have an intake valve not seating (& a bad PCV valve). The valve could be burnt, wedged open, or the spring could have broke.

If you run it like that, the air-fuel mixture will get diluted and cause the engine to run lean. Not good for the engine. PCV Valve's hose goes back to the intake and supplies manifold vacuum to the valve when running - not a breather system.

The blow-back into the intake also has the opportunity, slight but real, to to fill the bilge. Being potentially explosive, another reason not to run it.

The only way I'd run it would be for a docking manuever with high wind or current, and then, not any longer than necessary.

You could pull the rocker cover over the bad cylinder and see if there's anything wrong with the valve train that could be 'fixed' easily."
 
"Everything on the engine is n

"Everything on the engine is new, heads, risers, manifolds, ignition etc. So i don't believe the valves are an issue. The rings on that cylider are probably gone? I'm going to replace the engine, but would like to make better time in route. I think slow is the best option though?
Thanks for your help."
 
"If its not the intake valve,

"If its not the intake valve, how else are you getting warm air out of the PCV valve? It is a PCV valve, not just a tube between the flame arrestor and the valve cover?

I've never seen rings fail and yield a zero on a compression gauge. Now a hole in the piston would give you a zero.

Did you get the top end rebuilt or did you put all new components on the top end? How did you adjust the rocker arms? Did you change the cam and the timing chain/gears, too?"
 
"The top is new. All the rocke

"The top is new. All the rocker arms are adjusted properly, chains gears all new. It is a PCV valve."
 
The mechanic has gone through

The mechanic has gone through the entire engine. I was confused about the warm air also. Any suggestions
 
"You sure the heads are new vs

"You sure the heads are new vs reman'd??

Does the 'warm air' exit the PCV valve in pulses, consistent with engine rpm?

Did the mechanic pull the rocker cover?"
 
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