So...i got very interesting leak down test results...

[mike911996]

Luckily, I was able to borrow the SNAP-ON leak down tester....very accuarate 100 psi tool....you might as well wipe your a$$ with the harbor freight tool....very inaccurate 15 psi crap tool....

anyway.... here are the results

1st test 2nd test
1 30% leakage 30.5%
2 10% 13.5%
3 9% 7.5%
4 3.5% 3.5%
5 3% 3%
6 88% 88%


So obviously the reason i was doing the test was because the engine has a miss.

I clearly found the offending cylinder...#6 I am pretty confident it is an intake valve for when i listen to the air i hear nothing in the exhaust pipe and when i take the oil cap off there is no sound of air pushing through as i unscrew the cap as there is with #1...

#1 ,as i said above, i believe the culprit could be the rings because as i unscrew the oil cap there is a clear sound of air pushing through as i unscrew the cap. there is also oil seepage when viewing #1 from under the car emanating between the cylinder and the head....

Am i correct in my understanding that there is no gasket between the cylinder and head in a 3.2 motor? also no loctite 574 as well?

#2 and #3 at roughly 10% is still considered very good...

#4 and #5 blew me away....that is like brand new rebuild specs right there....after many years of track driving to have those cylinders still tight as a drum is surprising and satisfying....

Is there precedent in 911 engine rebuilding for doing a top end and just refreshing one head on one side of the engine....and putting it all back together?? I mean look at my right side... 3% , 3% and 88%....theoretically, couldnt i pull the #6 head...get it refurbished and put it back together leaving #4 and #5 alone? Is this acceptable to do?

Thanks for reading....I would welcome any and all suggestions as to what to do with my engine considering my leak down results.

[Joe Bob]

Before tearing it down....do a valve adjust and a douche of Techron and/or Seafoam.

Diagnosing a ring issue can be done by tossing oil into the cylinder and doing a compression check.

[Rodsrsr]

Second on valve adjust. I had #6 at 85% leakdown caused by a way off adjustment. Cylinders #1,2 and 3 are borderline. 10% may be okay for a small block Chevy, but a Porsche motor should be around the 3% range.

[mike911996]

bump

[dad911]

Originally Posted by mike911996

bump

Didn't like the prior answers?

Originally Posted by mike911996

#6 I am pretty confident it is an intake valve for when i listen to the air i hear nothing in the exhaust pipe and when i take the oil cap off there is no sound of air ....

At 88% you should hear air out the intake. I'd re-do the test until I was 100% confident. And a valve adjustment would be a good idea.

Originally Posted by mike911996

#2 and #3 at roughly 10% is still considered very good...

Not in my book.....

Originally Posted by mike911996

....., couldnt i pull the #6 head...get it refurbished and put it back together leaving #4 and #5 alone? Is this acceptable to do?

Depends, are you keeping the car or going to dump it? If it was mine, I'd fix them all.

Originally Posted by mike911996

#1 ,as i said above, i believe the culprit could be the rings because as i unscrew the oil cap there is a clear sound of air

Yup, sounds like rings to me.

Originally Posted by mike911996

....after many years of track driving ......

I'll bet you find alot more when you pull her apart.... guides, valves, worn springs......

[Joe Bob]

Tearing down a top end on a flat six isn't the same as a Chebby. Just getting to the heads is quite a job.....

Doing one jug would be not real smart.

[hcoles]

Why would valve adjust affect readings? The valves are closed. I'll assume the adjustment is not bad enough to hold the valve open.

[Joe Bob]

It's assuming that a tight valve would be holding it open and not sealing correctly. Tossing oil in after a compression check and checking again, would temporarily seal up rings but not a valve.

[Grady Clay]

Your first mission should be to go drive your 911 for a bit.
Some good ‘sporting driving’ (aka ‘Italian tune-up’) is good for the engine.
This will allow you to re-test with more confidence.
If the numbers are different, I would not hesitate to go through this cycle a few times to have high confidence in the numbers.
Diagnose, diagnose, diagnose – then fix if necessary and fix the right problem.

I agree, adjust the valves – after some driving.
One issue that occurs if the valve clearance is adjusted with carbon on a valve seat.
After the carbon falls off, the clearance closes and damage to the valve and seat can result.

It is also useful to perform the cranking compression test.
This will give you results of the dynamic condition of the engine while the cylinder leak test is static at TDC compression.
As Joe Bob notes, oil in cylinder can separate ring from valve issues.


I agree, 10% is functioning but not acceptable for a good 911 engine.
I have seen many with all 2-3% after 100K miles.



NO, you should not repair a single cylinder or one bank.
If your numbers are confirmed, do a complete – whatever is necessary to all cylinders.
Fix it right the first time.

Best,
Grady

[euro911sc]

If you feel you have something that needs fixin' after following Grady's todo list: Fix em all... 80% of the work is getting the heads off anyway. Splitting the case after that is peanuts...

[WANNA930]

RETEST with the Harbor Freight and maybe the numbers would be better??

Only kidding I think you are getting some good advise. I would also redo test before diving in as if you open it up you aren't just doing one.

[aston@ultrasw.c]

Before you "open it up" be sure you understand the costs to put it back together again, you may be in for a nasty shock.

[Rodsrsr]

Originally Posted by aston@ultrasw.c

Before you "open it up" be sure you understand the costs to put it back together again, you may be in for a nasty shock.

Plus one on that. I hate to say it again but.....these are not SBC motors.