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EmptyGarage's Avatar
 
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How do you intrepret Leakdown results

#3 - 2% #6 - 4%
#2 - 8% #5 - 8%
#1 - 3% #4 - 2%

Everybody says do leakdown...but now what? What do these mean? And not just that cylinder #2 leaked 8% during test, how do you interpret a set on number like this?

Last edited by EmptyGarage; 01-08-2010 at 02:25 PM..
Old 01-08-2010, 02:22 PM
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Quote:
Originally Posted by EmptyGarage View Post
#3 - 2% #6 - 4%
#2 - 8% #5 - 8%
#1 - 3% #4 - 2%

Everybody says do leakdown...but now what? What do these mean? And not just that cylinder #2 leaked 8% during test, how do you interpret a set on number like this?
10% and under is great, unless you are anally retentive.
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Old 01-08-2010, 03:53 PM
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Was this test done on a warm or cold motor? How many miles on the motor?
Old 01-08-2010, 04:44 PM
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Not only are the absolute numbers important (obviously lower is better), but you also want them clustered together closely, and (even more importantly, I'm told) the tech who did the test should also be able to tell from where the motor's "leaking."
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Old 01-08-2010, 05:58 PM
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Quote:
Originally Posted by DonE View Post
Was this test done on a warm or cold motor? How many miles on the motor?
Mileage was 52K and tested at Turbo-Kraft so Done right.
Old 01-08-2010, 07:50 PM
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So could they tell if cyl 2 and 5 were an intake, exhaust or blow by leak? I've had hard time telling where the air goes on my other engines while the engine was in the car, thats why I ask.
Old 01-08-2010, 09:42 PM
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The numbers you are looking at are the percentage of air leaking by
1) The rings?
2) The intake valve?
3) The exhaust valve?

It is performed by pulling all the spark plugs. Then putting compressed air in the Cyl on the compression stroke or TDC ( Top Dead Center) then the little amount of air that leaks by is the % # you are reading. The engine must be cold for proper results!

Hope this helps you under stand a little better.

These numbers look good! i bought a 88 930 with 58k miles and number 2 cyl was at 45% the air was blowing right out the exhaust. i bought the car 9k cheaper then asking price and it ended up being the valve guide.
So I pulled the engine tore it down and completely upgraded to all the common mods and now it will run circles around my 89!! Night and Day!!!!

They are great stock till you drive a modified beast.
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Old 01-09-2010, 03:15 AM
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Quote:
Originally Posted by Noah930 View Post
Not only are the absolute numbers important (obviously lower is better), but you also want them clustered together closely
On a brand new or freshly rebuilt engine, maybe.
On an engine that's got 52k miles, not gonna happen.
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Old 01-09-2010, 04:39 AM
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Quote:
Originally Posted by EmptyGarage View Post
Mileage was 52K and tested at Turbo-Kraft so Done right.
Maybe - I hope so.

Those are good numbers for the miles on your motor, IMO. The 2% seems a bit of a stretch, but OK - that's great for you.

What did TK tell you about the numbers? What prompted you to do a leak-down?
Old 01-09-2010, 10:03 AM
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Quote:
Originally Posted by DonE View Post
Maybe - I hope so.

Those are good numbers for the miles on your motor, IMO. The 2% seems a bit of a stretch, but OK - that's great for you.

What did TK tell you about the numbers? What prompted you to do a leak-down?
Part of purchase documentation. Test was performed over 1 year ago. will have car re-tested before purchase, comparing the two results over year apart should be interesting. i will post results if purchase goes that far.

Some information I've requested a couple of times is not being disclosed so It's making me cautious.
Old 01-09-2010, 11:22 AM
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Smart.

I've been watching my #2 cylinder fall in compression, so since the weather sucks, I pulled my motor today to check it out. It only has about 10k on it, so we'll see what's going on tomorrow.
Old 01-09-2010, 06:58 PM
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Quote:
Originally Posted by TURBO TALES View Post
These numbers look good! i bought a 88 930 with 58k miles and number 2 cyl was at 45% the air was blowing right out the exhaust. i bought the car 9k cheaper then asking price and it ended up being the valve guide.
Why do you think it was a valve guide? I just can't see a guide leading to a 45% leak from combustion chamber? Maybe if the guide is all gone but that would smoke like hell. Just trying to figure how it would leak to learn
Old 01-10-2010, 01:02 AM
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The valve guide was worn out and the valve wouldn't seat properly! i found this out by pulling the valve cover and while the compressed air was in the cylinder i could take a rubber hammer and move the valve side to side and change the % of the leak!

I also removed the rocker to make sure! There are times when the valve adjustment may be to tight so loosening up the crows foot takes that out of the loop. The car did smoke on cold starts a little to much for my likings.
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Old 01-10-2010, 03:15 AM
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Ok, so the guide can be so worn it makes the valve not seat 100%. Thats good to know for future troubleshooting.
Old 01-10-2010, 03:54 AM
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