#'s on a leakdown test.
10-19-2006 | 08:19 PM
#1
Thread Starter
Rest in Peace
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Joined: May 2006
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From: Bird lover in Sharpsburg
#'s on a leakdown test.
How many of you have done a leakdown test on your 928? I am curious as to what readings you got.
I am trying to make a determination of whether to replace my rings when I pull the motor on my 87.
I am not sure what a 32 valve engine should have as far as leakdown #'s
I would think any thing under 5% would be great.
6-10% ok
11-15 % marginal
anything over 15 would be cause for a teardown, what are you guys thoughts?
Any body ever done a fresh engine that had just been broken in?
BTW, mine were at, #1, 6% #2, 9% #3, 8% #4, 8% #5, 6% #6 ,6% #7, 8% #8, 8%. Starting with the motor hot and redoing the first 2 cylinders to make sure nothing changed.
This is a 125,000 mile engine, or at least that is where the odometer stoped at, and I have not put many miles on it since I bought it. The PO said the odometer did work the last time he drove it.
I wanted them to be a little better than that, or worse than that, now I do not have a easy decision to make
.
I am trying to make a determination of whether to replace my rings when I pull the motor on my 87.
I am not sure what a 32 valve engine should have as far as leakdown #'s
I would think any thing under 5% would be great.
6-10% ok
11-15 % marginal
anything over 15 would be cause for a teardown, what are you guys thoughts?
Any body ever done a fresh engine that had just been broken in?
BTW, mine were at, #1, 6% #2, 9% #3, 8% #4, 8% #5, 6% #6 ,6% #7, 8% #8, 8%. Starting with the motor hot and redoing the first 2 cylinders to make sure nothing changed.
This is a 125,000 mile engine, or at least that is where the odometer stoped at, and I have not put many miles on it since I bought it. The PO said the odometer did work the last time he drove it.
I wanted them to be a little better than that, or worse than that, now I do not have a easy decision to make
.
10-19-2006 | 08:29 PM
#2
Instructor
Joined: Mar 2006
Posts: 205
Likes: 0
From: Hattiesburg, MS
My PO had a leakdown test done 5 and a half years ago. Looking at it now. I'm a little concerned about cylinder 2. My results are below. What does the anamoly of cylinder 2 mean?
1 - 5%
2 - 12%
3 - 3%
4 - 6%
5 - 4%
6 - 4%
7 - 4%
8 - 6%
1 - 5%
2 - 12%
3 - 3%
4 - 6%
5 - 4%
6 - 4%
7 - 4%
8 - 6%
10-19-2006 | 08:32 PM
#3
Burning Brakes
Joined: May 2005
Posts: 1,007
Likes: 9
From: Chilton Wisconsin
Those numbers look pretty good to me, but I don't have numbers on my 928 to compare. The spread is fairly tight (6-9%) and all are under 10%. Did you notice if the leakage was always from teh same area (i.e. intake, exhaust, or crankcase)?
Is there any other reason to pull pistons? How is the oil control?
If the oil control is good and there is no other reason to pull the pistons I would leave them alone.
Is there any other reason to pull pistons? How is the oil control?
If the oil control is good and there is no other reason to pull the pistons I would leave them alone.
10-19-2006 | 08:43 PM
#4
Three Wheelin'
Joined: Nov 2003
Posts: 1,577
Likes: 0
From: Los Angeles, CA
Generally speaking, anything under 10% is pretty decent for a motor with miles on it. Consistency is also important here... if they're all fairly close to each other, then you're probably just fine. I wouldn't even worry about putting money into rebuilding the block unless you were in the 20%+ range.
10-19-2006 | 08:46 PM
#5
928 OB-Wan
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From: Zebulon, NC
110k+ miles and all under 10 is great...
generally anything over 15, or a cylinder 5% greater or lesser than the rest could be a concern, ie the 12 on the above test, which is 6% greater than the next closest number
generally anything over 15, or a cylinder 5% greater or lesser than the rest could be a concern, ie the 12 on the above test, which is 6% greater than the next closest number
