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Discussion Starter · #1 ·
I posted a few weeks ago about a loud knocking in my motor. Figured it was probably a rod bearing. I just pulled the plugs to do a compression check and cylinder #7 had 270 lbs of compression and had antifreeze in it. The other cylinders have the usual 225 lbs. The oil looks fine and antifrezze looks bright green. Where do you think its leaking and why is car knocking???? Its a 72 malibu convertable with a 350 motor.( Dart heads)
 

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If radiator fluid is in your combustion chamber you have most liekly blown a head gasket. It's odd that you are getting compression in that cylinder though. This would mean the water is coming from the valve seats (as did mine), but I doubt that with new(?) dart heads.

My situation was such: intake/exhasut seat on #4 cylinder brahed into a water jacket. chamber filled with some fluid (because system is pressurized when hot). piston came up. Water does NOT compress easily. Rod bent. shorter rod came back down. Crank lobe hit piston skirt. **** broke.


You might have a slight condition of this happening?

I'd pull the head to find why water is in the chamber. the knock may show itself during all of that.

-good luck



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71' 3880# with me. Big Block 402, Merlin oval heads, 10.2:1CR, TH400, 3.73 posi,
1/8th: 8.2 @ 86.8mph
1/4: 12.7 @ 107.8mph (1.93 sixty foot)
--have pulled a 1.85 sixty foot (before street tires or course).
Picture of me roasting the tires and other guy stuff
Video of me staging (smoke of course)
 

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Cracked or blown head gasket, cracked head or block. DON'T RUN IT ANYMORE UNTI YOU FIND THE PROBLEM!!! You will have top pull the head and take a look.

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MalibuJerry350
TC Member #1279
Original owner '70 Chevelle.
560,000+ miles on car.
Hey, if it's got wheels, DRIVE IT!
My Chevelle: http://hometown.aol.com/erie614/myhomepage/index.html
 

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Anti freeze can be coming across the intake gasket. That would explain the compression in that cylinder being good. Take a look at the intake gasket when you tear it down.



[This message has been edited by Mike Feudo (edited 09-13-2001).]
 

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Discussion Starter · #5 ·
Could it be that its just an intake gasket? I only drove it a block when the noise started and it idles just fine in park. When I put it into drive with the brakes on ,it idles rough.
 
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