Click for CL Yachts 99X Click for Ocean Alexander Click for Ocean Alexander Click for Northern Lights Click for Westport

12v-71n Water Pump Oil Seal Replacement

Discussion in 'Engines' started by PPD, Oct 26, 2026 at 9:33 PM.

You need to be registered and signed in to view this content.
  1. PPD, Oct 26, 2026 at 9:33 PM
    #1
    PPD

    PPD Member

    Joined:
    May 17, 2020
    Messages:
    94
    Location:
    CT
    Looks like the oil seal on my port engine water pump went. Starting to weep oil from the weep hole on the backside of the pump. Does anyone know of any special tips or tricks to this task that I should be aware of before I pull it off? This is my first time working on one off the detroits.
    Thanks
  2. boatpoor, Oct 26, 2026 at 9:49 PM
    #2
    boatpoor

    boatpoor Senior Member

    Joined:
    May 4, 2016
    Messages:
    305
    Location:
    32407
    They are pretty simple pumps. If you got the original engine manuals just follow the instructions.
  3. Capt J, Oct 26, 2026 at 10:32 PM
    #3
    Capt J

    Capt J Senior Member

    Joined:
    Jul 11, 2005
    Messages:
    14,898
    Location:
    Fort Lauderdale
    Make sure the bearing isn't going out, as that will cause the oil seal to start leaking.
  4. Capt Ralph, Oct 26, 2026 at 10:40 PM
    #4
    Capt Ralph

    Capt Ralph Senior Member

    Joined:
    Sep 8, 2004
    Messages:
    14,580
    Location:
    Satsuma, FL
    Rear raw water pump oil seal?
    Sometimes can be confused with the rear tach sender leaking oil.
    Sometimes the back of the heads leaking also. Also oil leaking down from the blower drive, blowers and throttle control leaking down hill.
    Takes some crawling back there to carefully follow the oil trail.
    Usually easy work. When in doubt, look at the pictures.

    Oil seal behind the front coolant circulating pump?
    Rare failure.
    Usually the head end bolts holding the thermostat housing, that lil hose between the governor housing and the head, PTO across from the coolant circulating pump can sling oil that way, valve cover gasket or something else leaking oil up front.
  5. PPD, Oct 28, 2026 at 3:56 PM
    #5
    PPD

    PPD Member

    Joined:
    May 17, 2020
    Messages:
    94
    Location:
    CT
    From my investigations so far, it seems to be originating from the backside of the front coolant pump. No evidence of any oil dripping or staining above the weephole on the backside of the pump.
  6. Capt Ralph, Oct 28, 2026 at 5:00 PM
    #6
    Capt Ralph

    Capt Ralph Senior Member

    Joined:
    Sep 8, 2004
    Messages:
    14,580
    Location:
    Satsuma, FL
    Yep, Lets look in there very carefully.
    Like I stated before, that seal rarely leaks. Usually the bottom thermostat mounting bolt.

    If that seal is really leaking oil; The H/E lower pipe, probably the oil cooler pipe and right thermostat housing comes off, then the whole front coolant pump comes off.
    The H/E (heat exchanger) should stay in place.
    All of your coolant will have to be claimed before any service.
    Can you make St Augustine or Jax this fall?