compression Q's
Thread Starter
Supreme Member
Joined: Jan 2001
Posts: 1,236
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From: Brockton, MA, USA
Car: 1983 Z28
Engine: 6.6L 406
Transmission: T-56
compression Q's
What are some things that could make an engine lose compression in some cylinders? Is age just what does or could somehting make it happen?
TGO Supporter
Joined: Aug 1999
Posts: 14,811
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From: Jackson County
compression either leaks pass the valves or pass the rings, plus the ocassional head gasket leak. so one of the three would be bad to have compression drop.
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ICON Motorsports
1st & 3rd
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ICON Motorsports
1st & 3rd
Junior Member
Joined: Feb 2001
Posts: 8
Likes: 0
From: W. Townsend Ma
You sure you have the tester set up right you should get something even a little bit. was it the same on all the cylinders or just one of them, maybe the tester is bad? what was the problem with the motor to begin with...
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Joined: Jan 2000
Posts: 19,658
Likes: 310
Super83,
If the engine is running at all, you ahould at least be able to read 50 PSIG on some of the cylinders.
Make sure the battery is fully charged, all the spark plugs are removed, the throttle is blocked to the fully opened position, and that you crank the engine through at least four complete combustion cycles (at least eight revolutions.
If the tester does not indicate any compression, I'd suspect the tester or its connection to the head. Make sure the connection hose has the seal or 'O' ring in place to seal the connection to the cylinder.
As a remote possibility, if the engine is not running and there is no compression on any of the cylinders, you make have lost a timing chain or belt. What engine are you analyzing, and what are some more of the specific symptoms?
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Later,
Vader
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"I'm'a do Things My Way - It's My way or the Highway."
Adobe Acrobat Reader
If the engine is running at all, you ahould at least be able to read 50 PSIG on some of the cylinders.
Make sure the battery is fully charged, all the spark plugs are removed, the throttle is blocked to the fully opened position, and that you crank the engine through at least four complete combustion cycles (at least eight revolutions.
If the tester does not indicate any compression, I'd suspect the tester or its connection to the head. Make sure the connection hose has the seal or 'O' ring in place to seal the connection to the cylinder.
As a remote possibility, if the engine is not running and there is no compression on any of the cylinders, you make have lost a timing chain or belt. What engine are you analyzing, and what are some more of the specific symptoms?
------------------
Later,
Vader
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"I'm'a do Things My Way - It's My way or the Highway."
Adobe Acrobat Reader
Thread Starter
Supreme Member
Joined: Jan 2001
Posts: 1,236
Likes: 0
From: Brockton, MA, USA
Car: 1983 Z28
Engine: 6.6L 406
Transmission: T-56
Thanks for your help guys but I found the culprit: I had two bent exhaust valves! so it was only running on 6-cylinders. It is getting rebuilt as we speak! thanks again.
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I WOULD RATHER PUSH A CAMARO THAN DRIVE AN IMPORT
1983Z28 350w/ edelbrock performer RPM power package with 64cc aluminum heads, dynomax shorty headers, 700R-4 with shift kit, 750cfm carb, edelbrock 3" exhaust system, ASCD SS hood, 16" IROC rims.
future mods:
completely done over suspension, black paint with flames, Hurst shifter, dakota digital gauge package, procharger supercharger.
------------------
I WOULD RATHER PUSH A CAMARO THAN DRIVE AN IMPORT
1983Z28 350w/ edelbrock performer RPM power package with 64cc aluminum heads, dynomax shorty headers, 700R-4 with shift kit, 750cfm carb, edelbrock 3" exhaust system, ASCD SS hood, 16" IROC rims.
future mods:
completely done over suspension, black paint with flames, Hurst shifter, dakota digital gauge package, procharger supercharger.
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