Compression Test - Team Camaro Tech
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post #1 of 3 (permalink) Old Jun 16th, 00, 10:18 AM Thread Starter
 
Join Date: Dec 1999
Location: New York
Posts: 15
Question

I did a compression test dry/wet yesterday after hearing a slight ticking noise #1 cyl. All cyl were good 165 lbs ( 400 sm blk) except that #1... around 105 lbs. Any ideas on what to expect /look for when I start tearing the heads off ??? Oil pressure is down also.

I get about 38lbs at initial startup, but drops after engine is warm...about 25 -30 lbs
at 2500rpm...I should see at least 40lbs
correct ?

I get some oil smoke on deaceleration...my guess it's time for new heads.
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post #2 of 3 (permalink) Old Jun 16th, 00, 07:14 PM
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David Pozzi
 
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Join Date: Nov 1999
Location: Central California, USA
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If you had a rod bearing problem the piston might hit the head. Or a cracked piston or broken ring land. That would produce blowby under acceleration.
Possibly the head gasket leaking?
Go around it with a piece of hose up to your ear like a stethescope and see if you can pinpoint it.
Also check the fuel pump, it can do it. And it's in that area. There is a rubber bushing under a fork that lifts the diaphram. If it splits and falls off it can tick.
David

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post #3 of 3 (permalink) Old Jun 17th, 00, 03:20 AM
 
Join Date: May 2000
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You might want to buy,barrow or rent a cylinder leakage tester.With the piston at TDC on compression with both valves closed you introduce compressed air into the cylinder.The gauge will give a percentage of leak down,0-10%is good,15-20%is iffy and 20 or worse is time to do a tear down.You can do the the test with just compressed air but you won't have leakage figure.Remove the oil filler cap,pvc valve,dipstik and radiator cap.Listen to where you hear air leaking from.Oil filler,dipstik = rings or piston.Carburetor or fuel injection intake = intake valve leaking.Exhaust pipe = exhaust valve leaking.Bubbles in radiator = blown head gasket or a crack in head or block.ONE WORD OF CAUTION!IF YOU USE A SOCKET TO TURN THE ENGINE OVER REMOVE IT AND KEEP ALL BODY PARTS AWAY FROM FAN,BELTS AND PULLEYS.WHEN YOU PUT AIR PRESSURE INTO THE CYLINDER,IF THE PISTON IS NOT AT ABSOLUTE TDC PRESSURE WILL SPIN THE ENGINE OVER.
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