Results 1 to 5 of 5

Thread: no compression

  1. #1
    Registered User
    Member ID
    CZCC-16936
    Join Date
    May 2008
    Location
    arizona
    Posts
    81

    Default no compression

    Hi,

    I just had my 260 engine rebuilt. It is running like s**T. I did a poor mans compression test (finger over the spark plugs while cranking engine) and the # 5 seemed to have no compression. In any case the engine is under warranty and the company that rebuilt it seems to be rather clueless. I say this because they want to check the carbs as they think this may be the issue. Now I do not claim to be Mr. Goodwrench but my understanding of this engine leeds me to believe that if there is no compression or very weak compression it would either be the valves or the rings. Would someone please let me know if there could be other reasons besides the rings or valves or if I am clueless with my ring/valve theory. By the way they claimed they checked the valves and that they are fine which is why they are moving to the carbs.

    Thanks
    Glenn

  2. #2
    No more body roll! SteveJ's Avatar
    Member ID
    CZCC-5413
    Join Date
    Dec 2003
    Location
    Gainesville, GA
    Age
    54
    Posts
    3,651

    Default

    You could always buy a gauge and test the compression yourself. While you're at it, buy a timing light, too. Also, how do your plugs look? Are you sure you're getting enough fuel to the carbs?

    Get a set of feeler gauges, a remote starter, and a socket set. Take off the valve cover and check the clearances. The measurements are all in the FSM. If you're not sure if something looks right, take pictures and post them.

    There aren't enough facts in you post to tell you whether or not you're on the right track.

    By the way, did you get the rebuild done by a place that specializes in early Z cars?
    73 240Z
    74 260Z

    Blue's collection of tech tips - A great place to look for answers
    XenonS30 -The cheap source for FSMs
    Georgia Z Club
    Fiddling with Z Cars - Z car tips & tricks and pictures of my car-loving life.
    Steve's CARtography - Just car pictures.

  3. #3
    Registered User
    Member ID
    CZCC-16936
    Join Date
    May 2008
    Location
    arizona
    Posts
    81

    Default

    Steve,

    It is a Japenese engine rebuilding company..The owner has a few Z'S and there were a few customer Z'S in the lot as well. Since the engine has only a few hours run time on it and is under warranty it is probably best for them to seek out the issues. I guess I am trying to determine if I should be as concerned as I am because I do not see the connection to no compression and the carbs. I am not Mr Good wrench but I do not see the carb connection. They said they checked the valves and they are fine, I would think the next moves would be either head gasket or rings. How does the Carb figure into this-if it does then I guess I must have confidence in there approach if it does not then maybe they do not know what they are doing. The number 5 and 6 spark plug seemed to have a much darker look then the #1 through 4 plugs. Everything has spark, the engine starts but runs very rough like it is missing and with the finger compression test # 5 does not push back on my finger at all which at first would, in my opinion seem to indicate a stuck valve however they said valves are fine and since the # 6 seems weaker then the #1 through 4 I am thinking head gasket. They said the plugs are not wet so it cannot be the rings, they also did not remember the compression test readings from the compression test they claimed to have performed. Not very happy at this point. What are your thoughts?

    Glenn
    Last edited by zdude1967; 07-14-2011 at 12:52 PM.

  4. #4
    No more body roll! SteveJ's Avatar
    Member ID
    CZCC-5413
    Join Date
    Dec 2003
    Location
    Gainesville, GA
    Age
    54
    Posts
    3,651

    Default

    My thoughts? Well...
    Empirical tests are typically more trustworthy than subjective tests. Compression gauges aren't expensive. It's easy to do a compression check. If you think it's the valves, that isn't too difficult to check, either. If you're not feeling too comfortable doing those tests, buy some beer and find a friend who is comfortable with checking.
    As for the plugs, it 5 & 6 aren't wet, it's probably not too much oil/gas. Rings have to seat.
    The shop is fingering the carbs because they believe the compression is good and that poor fuel delivery is causing the car to run like crap.
    73 240Z
    74 260Z

    Blue's collection of tech tips - A great place to look for answers
    XenonS30 -The cheap source for FSMs
    Georgia Z Club
    Fiddling with Z Cars - Z car tips & tricks and pictures of my car-loving life.
    Steve's CARtography - Just car pictures.

  5. #5
    Registered User 5thhorsemann's Avatar
    Member ID
    CZCC-22854
    Join Date
    Nov 2010
    Location
    maryland
    Age
    55
    Posts
    1,398

    Default

    If you still have the original flat top carbs on the car, that would be my starting point as well.

Thread Information

Users Browsing this Thread

There are currently 1 users browsing this thread. (0 members and 1 guests)

Similar Threads

  1. Compression Help
    By Chart505 in forum Help Me !!
    Replies: 11
    Last Post: 07-15-2009, 10:43 AM
  2. Compression 71 240
    By rtaylor in forum Engine and Drivetrain (S30)
    Replies: 7
    Last Post: 12-12-2006, 07:41 PM
  3. Bad Compression on #1
    By zack_280 in forum Engine and Drivetrain (S30)
    Replies: 2
    Last Post: 11-20-2005, 07:55 PM
  4. Compression Rod - NEED HELP!
    By st0878 in forum Help Me !!
    Replies: 4
    Last Post: 12-20-2004, 05:38 PM
  5. Compression
    By JEFF in forum Engine and Drivetrain (S30)
    Replies: 9
    Last Post: 08-28-2004, 02:47 AM

Tags for this Thread

Bookmarks

Bookmarks

Posting Permissions

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