Results 1 to 4 of 4
  1. #1
    Join Date
    Aug 2013
    Location
    St. Louis
    Posts
    181

    Default help with compression values and decision to repair stringers

    My '89 Sunsport 351 PCM is at a decision point. We got the bottom repainted and back on the water this week. Top end was terrific and it was happily purring along at 38 mph (last year with scum on bottom WOT was 32ish). Then the drive shaft separated from the coupler. We got it back together and idled home. The coupler and transmission were 3/16" off to port. The drive shaft was clearly to port in the shaft log and the strut seems a little bent. We put a wrench on the motor mounts and they all feel pretty loose. We don't remember hitting anything last year, and worried the soft motor mounts allowed the motor to move. So it seems the inevitable day has arrived.

    We have a local marina looking at it. They has experience with stringer repair and experience aligning bent struts and drives shafts. We should get a quote soon. Ball park over the phone was the expected 4-5k.

    I did a compression test before taking it up to them. I was on the hose and engine temp was 120.

    1: 110
    2: 108
    3: 105
    4: 105
    5: 105
    6: 105
    7: 110
    8: 120

    I don't have an oil squirter, so I didn't do the "wet" compression values. I was using a HarborFreight tool.

    The numbers seem a little low to me, but all reasonably close to each other, and no cylinder is terrible. Should I be worried about investing in a new floor based on those numbers? My sense is to probably move forward. We'll see what their final quote looks like.
    Last edited by scottschmitt; 04-08-2020 at 06:03 PM.

  2. #2
    Join Date
    Aug 2013
    Location
    St. Louis
    Posts
    181

  3. #3
    Join Date
    Jul 2007
    Location
    Flowery Branch Georgia
    Posts
    2,458

    Default

    No doubt the engine is misaligned or the strut is bent. After 30 years I would be surprised if it didn't need stringers. You said the engine ran fine the compression numbers are a little low but also pretty even. How many hours do you have on the boat? General propeller is a good place for your shaft repair.

  4. #4
    Join Date
    Aug 2013
    Location
    St. Louis
    Posts
    181

    Default

    Boat has 830 hours. Thanks for the recommendation for shaft repair.

    I don't know if the compression might have been higher if I had gotten the engine temp up higher. On the fake-a-lake, it stayed pretty even at 120 degrees. Maybe I could have disconnected the water pump for a little bit.

Posting Permissions

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