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  #16 (permalink)  
Old 07-31-2013, 10:02 PM
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Still curious though does anyone have any idea why I would get good compression readings but a poor leak down result

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  #17 (permalink)  
Old 07-31-2013, 10:07 PM
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cut a hole in the bottom of a bucket and fill it up faster than the water can leak out
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  #18 (permalink)  
Old 08-01-2013, 04:36 AM
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So that being true the leak test does not prove that this is my issue because there is not enough time for the air to leak out when the engine is running
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Old 08-01-2013, 06:42 AM
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A leak down test tells you what percentage is leaking from what cylinders and where the leaks occur. Race cars leak less than street cars.How much leak down you will tolerate is up to you. as the engine leaks more it indicates wear or damaged parts. A fresh engine leaks less and makes more power and smokes less,,,,
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Old 08-01-2013, 07:07 AM
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well 8-12% , if they are all doing that.. and you have a turbo.. if it's 8-12 % from a 100psi air flow
what type of air you thinks getting past the rings when the turbo is spooled up..
go test them all.. was the file fit rings gap set up for the extra heat of the turbo?
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Old 08-01-2013, 08:35 AM
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gear head that was one of my original thought when pressure is being introduced to the cylinder by way of turbo the amount of leakage has got be greater... the percentage gauge reads 10% leakage but it sure feels like a whole lot of ait to me
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Old 08-02-2013, 01:14 PM
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Ok guys here's what I found after leak testing all cylinders
1-150psi comp 15% leak 2-160psi comp 8% leak
3-150psi comp 40% leak. 4-155psi comp 21% leak
5-140psi comp 28% leak. 6-150psi comp 14% leak
7-150psi comp 14% leak. 8-150psi comp 12% leak

All of which I feel at the breather hole in the valve cover and the dipstick tube. I suppose the next step is to start tearing the engine apart to probably due a set of rings right? What do you guys think?
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Old 08-02-2013, 01:25 PM
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open it up and look..
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Old 08-02-2013, 02:04 PM
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Originally Posted by Pupsvette76 View Post
Ok guys here's what I found after leak testing all cylinders
1-150psi comp 15% leak 2-160psi comp 8% leak
3-150psi comp 40% leak. 4-155psi comp 21% leak
5-140psi comp 28% leak. 6-150psi comp 14% leak
7-150psi comp 14% leak. 8-150psi comp 12% leak

All of which I feel at the breather hole in the valve cover and the dipstick tube. I suppose the next step is to start tearing the engine apart to probably due a set of rings right? What do you guys think?
I have seen that on newly built engine and the compression test was fine but leak down where up to 40% and the problem the owner was having is the oil would be dirty in less then 100 miles. Even after 4000 miles it would not seal up.

This was a Corvette 327 that was .040 over went .060 and torque plate honed the cylinders problem went away.

Here are the links on this build.

Oil pressure problem saga - Corvette Forum

Engine rebuild "Oil pressure saga" update - Corvette Forum
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  #25 (permalink)  
Old 08-02-2013, 02:07 PM
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How does that happen on a new rebuilt? Rings not seat/ break in to cylinders well?
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Old 08-02-2013, 02:16 PM
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Originally Posted by Pupsvette76 View Post
How does that happen on a new rebuilt? Rings not seat/ break in to cylinders well?
your case I think the rings ends butted or you got into detonation and broke the ring lands.. and/or rings.

the wrong cross hatch for rings..
iron/moly/chrome all want different set up's..
boring the block with torque plates but they used bolts, you use studs..
oval cyl..
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Old 08-02-2013, 02:28 PM
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Originally Posted by Pupsvette76 View Post
How does that happen on a new rebuilt? Rings not seat/ break in to cylinders well?
Here are some links to look over.

Values Of Torque Plate Honing - Team Camaro Tech

Leak Down test and blow by - Chevelle Tech
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  #28 (permalink)  
Old 08-02-2013, 02:38 PM
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More pics why a torque plate should be used.




.[/quote]
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  #29 (permalink)  
Old 08-02-2013, 02:58 PM
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It's hard to see but does that bottom cylinder have two holes in it? Lol
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  #30 (permalink)  
Old 08-02-2013, 03:26 PM
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I'm sure I don't have anything like that going on but now that I think about it I did have an issue with the car running really rich may have washed a few of the cylinders down... If I got the engine re honed with a torque plate could I then do a re ring? I would really hate to have to have it bored out even more then buy pistons then I have to re balance the rotating assembly
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