Results 1 to 4 of 4

Thread: Leakdown Test Result Variablity

  1. 11-13-2024, 11:46 AM #1
    McOtto
    McOtto is offline
    Senior Member McOtto's Avatar
    Join Date
    Apr 2023
    Location
    Denver, CO
    Posts
    248

    Leakdown Test Result Variablity

    I am experiencing variability in leakdown results across historical tests on my low-milage (66K) 1972 911T with its original MFI system. Four tests have taken place over the last 17 years, 6,000 miles. Across the multiple tests, one cylinder always tests bad (10 - 15% range with ring leakage always indicated, not valves) and it is never the same cylinder.

    The leakdown results do not appear to be manifesting themselves in noticeably poor engine performance: Smooth idle. Good acceleration and throttle response without noticeable hesitation. Power seems to be normal across all RPM ranges. No gray or blue exhaust smoke when engine is cold and when it is warm. Not experiencing an inordinate amount of oil consumption.

    Well before my ownership, in 2007 at 60K miles a shop installed new Porsche-Mahle P&Cs. Is it possible the rings were installed improperly allowing them to move and the ring gaps align???

    Does anyone have any other theories?
    1972 911T Targa
    1985 911 Carrera (with circa 1988 RUF 3.4L 260 hp DIN Engine Kit)
    Reply With Quote Reply With Quote
  2. 11-13-2024, 05:54 PM #2
    Haasman
    Haasman is offline
    Senior Member Haasman's Avatar
    Join Date
    Apr 2011
    Location
    N.Calif., south of SF
    Posts
    2,016
    McOtto the is weird. Not the same cylinder across four tests. Have to ask who did the leak down tests? Same shop? Are they a Porsche specific shop or a do they work on a.lot of different makes.

    P&C's a 60k miles is very unusual.

    Tell us more- plug on the "bad" cylinder look good?
    Haasman

    Registry #2489
    R Gruppe #722
    65 911 #302580
    70 914-6 #9140431874
    73 911s #9113300709
    Reply With Quote Reply With Quote
  3. 11-16-2024, 06:16 AM #3
    mepstein
    mepstein is offline
    Senior Member
    Join Date
    Dec 2010
    Location
    Wilmington, DE
    Posts
    1,463
    I use a snap on gauge. Tests are always consistent. Sounds like either the gauge or technique.
    A part isn't purchased until paid.

    The 9 Store LLC.
    Reply With Quote Reply With Quote
  4. 11-16-2024, 06:12 PM #4
    Nickelplated5s
    Nickelplated5s is offline
    Senior Member
    Join Date
    Jan 2024
    Location
    PNW
    Posts
    263
    What's the Snap On #? I have a compression tester but not a leak down.
    Reply With Quote Reply With Quote
« Previous Thread | Next Thread »

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •  

Forum Rules


Message Board Disclaimer and Terms of Use
This is a public forum. Messages posted here can be viewed by the public. The Early 911S Registry is not responsible for messages posted in its online forums, and any message will express the views of the author and not the Early 911S Registry. Use of online forums shall constitute the agreement of the user not to post anything of religious or political content, false and defamatory, inaccurate, abusive, vulgar, hateful, harassing, obscene, profane, sexually oriented, threatening, invasive of a person's privacy, or otherwise to violate the law and the further agreement of the user to be solely responsible for and hold the Early 911S Registry harmless in the event of any claim based on their message. Any viewer who finds a message objectionable should contact us immediately by email. The Early 911S Registry has the ability to remove objectionable messages and we will make every effort to do so, within a reasonable time frame, if we determine that removal is necessary.