Advice on replacing sending units on a 1988 Sea Ray 300 Weekender?

Discussion in 'General Maintenance/Repair Questions' started by Gary Kelly, Feb 4, 2023.

  1. Gary Kelly

    Gary Kelly New Member

    2
    Feb 4, 2023
    1988 Sea Ray 300 Weekender
    (2) 260 HP MerCruiser Inboard
    Gauges work.
     
  2. Bill Curtis

    Bill Curtis Well-Known Member

    627
    Mar 24, 2022
    Eastern NC
    '95 220 Overnighter
    454 Mag. Bravo3 w/ 2.0:1 ratio gears and 28 pitch props
    454 Mag Bravo3. 2.0:1 ratio gears w/ 28 pitch props
    That was a tad vague.
     
    Chris-380 likes this.
  3. dwna1a

    dwna1a Well-Known Member PLATINUM Sponsor

    Apr 23, 2012
    James River
    88 Weekender 300 "Seahorse"
    Twins 350
    I’m willing to help as soon as I know the question.
     
  4. Golfman25

    Golfman25 Well-Known Member

    Sep 12, 2009
    IL
    1998 370 Sundancer
    7.4 MPI
    Simple. Buy sending unit. Replace. Open beer. Drink beer.
     
    Bill Curtis likes this.
  5. Bill Curtis

    Bill Curtis Well-Known Member

    627
    Mar 24, 2022
    Eastern NC
    '95 220 Overnighter
    454 Mag. Bravo3 w/ 2.0:1 ratio gears and 28 pitch props
    454 Mag Bravo3. 2.0:1 ratio gears w/ 28 pitch props
    Since the info is so vague, hopefully this is what you are looking for.
     

    Attached Files:

  6. Gary Kelly

    Gary Kelly New Member

    2
    Feb 4, 2023
    1988 Sea Ray 300 Weekender
    (2) 260 HP MerCruiser Inboard
    I bought the 1988 Sea Ray 300 Weekender a few weeks ago, and the previous owners had bought the sending units, but never had them installed. My question is where the access to the sending units is, I have found a small side hole with a cover on each side by the front seats, just wondering if there is another way to access the units. This is a small space to get into to replace these units. It might be the only way to access them.
     
  7. techmitch

    techmitch Well-Known Member PLATINUM Sponsor

    May 1, 2008
    Chesapeake Bay, Middle River/Frog Mortar Creek MD.
    1999 270 DA
    Twin 4.3s W/Alpa I Gen II's
    This was as close as I could find, hope it helps.
    https://s3.amazonaws.com/srweb-pvt-...ic/parts-manuals/1989__1989-300-WEEKENDER.pdf
    Welcome to CSR.
     
  8. Golfman25

    Golfman25 Well-Known Member

    Sep 12, 2009
    IL
    1998 370 Sundancer
    7.4 MPI
    The more specific you can be the better answers you will. Start with Sending units for what?
     
  9. SKybolt

    SKybolt Well-Known Member SILVER Sponsor

    Nov 11, 2014
    Kent Narrows, MD
    Reel Nauti
    460 EC
    Detroit 6v92TA
    (Low profile's)
    Alison Gears
    Westerbeke
    12.5kw Genset
    All you say is sending unit. Do you know which one? The water temp is located on top of the engine by the thermostat in the front. The oil is in a tough spot, under the exhaust manifold towards the rear of the engine. The transmission over temp is right on top of the trans. in the middle. Just look for wires and trace the wires to what the sending unit. The temp ones are like brass plugs and the oil is a small can. post a pic and explain a little more to get better help. Welcome to CSR.
     
  10. Lazy Daze

    Lazy Daze Well-Known Member TECHNICAL Contributor GOLD Sponsor

    Apr 21, 2009
    PA
    Various
    Various
    This. They are engine mounted.

    But let's back up another step... why are you replacing them if the gauges work? Does your alarm system also work? Although technically those are sensors, not senders.
     
  11. SKybolt

    SKybolt Well-Known Member SILVER Sponsor

    Nov 11, 2014
    Kent Narrows, MD
    Reel Nauti
    460 EC
    Detroit 6v92TA
    (Low profile's)
    Alison Gears
    Westerbeke
    12.5kw Genset
    Don't mean to nit pick, but if your going to correct me then let's get it right. They are actually "sending unit" as they are referenced on most sites, but Stewart Warner is the sending unit on that year SR unless gauges swapped over to something else. https://www.stewartwarner.com/products/senders-sensors-switches/

    Temperature and oil pressure are refenced as sending units, tachometer are referenced as sensors if they are electrical. Otherwise electro-mechanical are also sending units.

    Didn't we have this conversation in another thread? Anyway not trying to argue, so please take it as such. :)
     
  12. Lazy Daze

    Lazy Daze Well-Known Member TECHNICAL Contributor GOLD Sponsor

    Apr 21, 2009
    PA
    Various
    Various
    It wasn't directed towards you. What I meant was I agree with everything you said.

    I was adding that information (sensor vs sender) for the OP's benefit in distinguishing between a "sender" that sends information to a gauge and a "sensor" that trips the alarm. They CAN often be used interchangeably but this is how Mercruiser usually refers to them... so since we're talking about Merc's... ;)

    No, I didn't take any offense :)
     
    SKybolt likes this.
  13. SKybolt

    SKybolt Well-Known Member SILVER Sponsor

    Nov 11, 2014
    Kent Narrows, MD
    Reel Nauti
    460 EC
    Detroit 6v92TA
    (Low profile's)
    Alison Gears
    Westerbeke
    12.5kw Genset
    I guess to your point, it depends on what year you are discussing. The old analog world was sending units. In the Can bus world everything is a sensor. BTW, went to Merc school back in the 80's.
     
  14. Golfman25

    Golfman25 Well-Known Member

    Sep 12, 2009
    IL
    1998 370 Sundancer
    7.4 MPI
    You guys are posting more than the OP. :)
     
  15. SKybolt

    SKybolt Well-Known Member SILVER Sponsor

    Nov 11, 2014
    Kent Narrows, MD
    Reel Nauti
    460 EC
    Detroit 6v92TA
    (Low profile's)
    Alison Gears
    Westerbeke
    12.5kw Genset
    HaHa - But at least we'll know whats what at some point ...
     
  16. Lazy Daze

    Lazy Daze Well-Known Member TECHNICAL Contributor GOLD Sponsor

    Apr 21, 2009
    PA
    Various
    Various
    ... maybe :)
     
  17. Lazy Daze

    Lazy Daze Well-Known Member TECHNICAL Contributor GOLD Sponsor

    Apr 21, 2009
    PA
    Various
    Various
    I was in middle school... :D
     
  18. dwna1a

    dwna1a Well-Known Member PLATINUM Sponsor

    Apr 23, 2012
    James River
    88 Weekender 300 "Seahorse"
    Twins 350
    If we go by using the term sending units and the access holes. It must be fuel sending units. Yes that is your only way in. It’s a tough job to do but can be done by the owner. If the gauges are working it may just be the reading is incorrect due to the age of the cork
     
  19. Lazy Daze

    Lazy Daze Well-Known Member TECHNICAL Contributor GOLD Sponsor

    Apr 21, 2009
    PA
    Various
    Various
    Ha! I didn't even think of FUEL sending units!
     
  20. techmitch

    techmitch Well-Known Member PLATINUM Sponsor

    May 1, 2008
    Chesapeake Bay, Middle River/Frog Mortar Creek MD.
    1999 270 DA
    Twin 4.3s W/Alpa I Gen II's
    That's what I thought from the beginning and why I posted the link. Ya know, the one that fell on deaf ears.
     

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