Oil pressure problem or just the gauge?

Discussion in 'Gas Engines/Drives/Transmissions/Props' started by Shark, Sep 25, 2020.

  1. Shark

    Shark Active Member

    142
    Jun 16, 2020
    Sayville, NY
    2001 290 Sundancer
    Twin 5.0L EFI w/Bravo II Drives
    Took a 10 min ride to the fuel dock the other day, and noticed the starboard oil pressure gauge was only reading less than 20 psi (port was at 40psi, where they both usually are). We were cruising at around 3400-3600 rpm, both engines seemed to be running great, and synchronized. Throttled down into the no wake zone, and the gauge was at 0. No smoke, no noises, engines synchronized. Fueled up, checked the oil (both clean and in the OK zone), and bilge (no signs of oil or anything abnormal). Started the engines back up and the gauge never moved off 0. Engines ran fine again on the way back.

    I think it’s probably a problem with the gauge, sender, or wiring in between, but wondering if anyone has any other ideas or suggestions?
     
  2. Chip S

    Chip S Active Member

    316
    Jun 17, 2019
    Bordentown, NJ
    1993 Sea Ray 200 Overnighter
    1993 Mercury 150 hp Black Max Outboard
    If you short your gauge sender terminal to ground with the key in the On position the gauge should go to full (80 psi). If it doesn't you need a new gauge.

    Another less reliable way to tell if the gauge is dead is to watch the needle when you turn the key to On. The needle should move a little bit when you turn the key to On. If it doesn't move at all the gauge is probably dead.
     
    Chris-380, Shark and CaptRonn like this.
  3. CaptRonn

    CaptRonn Well-Known Member

    May 25, 2016
    on a large body of water
    1999 Sea Ray 400 Sedan Bridge
    Convert fuel into noise
    Another method is to swap gauges and see if the problem follows. Same with the senders.

    These gauges are not the best, and failures along with flaky readings can be expected.
     
    Shark likes this.
  4. Shark

    Shark Active Member

    142
    Jun 16, 2020
    Sayville, NY
    2001 290 Sundancer
    Twin 5.0L EFI w/Bravo II Drives
    Thanks for the advice guys. I really appreciate it. I’m going to check it out today.
     
  5. BEH

    BEH Active Member

    191
    Oct 8, 2018
    Lake Simcoe, Lake Nippissing & French River
    1990 20’ BR, Humminbird Helix 5, 3K Lb Trailer
    4.3 Mercruiser
    I had exactly the same thing happen in my SR 30 Sedan Bridge years ago.
    Was convinced it was the gauge.
    Wasn’t!
    Blew a hole through the block.
    Expensive lesson
     
  6. Shark

    Shark Active Member

    142
    Jun 16, 2020
    Sayville, NY
    2001 290 Sundancer
    Twin 5.0L EFI w/Bravo II Drives
    Oh wow..so the engine was running fine for a while with no oil pressure?
     
  7. BEH

    BEH Active Member

    191
    Oct 8, 2018
    Lake Simcoe, Lake Nippissing & French River
    1990 20’ BR, Humminbird Helix 5, 3K Lb Trailer
    4.3 Mercruiser
    Was running great, no warning, nothing.
    Was cruising about 3K RPM
    Then, BANG, put a rod through the block.
    Previous to this I was having problems with the gauge, mainly the one on the fly bridge.
    That’s why I assumed it was the gauge.
     
  8. Shark

    Shark Active Member

    142
    Jun 16, 2020
    Sayville, NY
    2001 290 Sundancer
    Twin 5.0L EFI w/Bravo II Drives
    Ok thanks for the heads up. I’ll test the gauge and sender before I go anywhere. Hopefully, I get lucky and it’s one of those or the wire.
     
  9. CaptRonn

    CaptRonn Well-Known Member

    May 25, 2016
    on a large body of water
    1999 Sea Ray 400 Sedan Bridge
    Convert fuel into noise
    On occasion a wire at the sender or on back of the gauge will build up some corrosion which will interfere with the gauge operation. Be sure to clean up all connections.
     
    Chip S likes this.
  10. Shark

    Shark Active Member

    142
    Jun 16, 2020
    Sayville, NY
    2001 290 Sundancer
    Twin 5.0L EFI w/Bravo II Drives
    I just started both engines and gauges are reading 40 port and 20 starboard..so maybe it’s not the gauge..seems like I might have an oil pressure problem..wouldn’t know where to start with that. Might have to call a mechanic now.
     
  11. CaptRonn

    CaptRonn Well-Known Member

    May 25, 2016
    on a large body of water
    1999 Sea Ray 400 Sedan Bridge
    Convert fuel into noise
    Did you swap gauges to see if the problem moves? Or swap senders?

    A bad sender will give erroneous info.
     
  12. Chip S

    Chip S Active Member

    316
    Jun 17, 2019
    Bordentown, NJ
    1993 Sea Ray 200 Overnighter
    1993 Mercury 150 hp Black Max Outboard
  13. Shark

    Shark Active Member

    142
    Jun 16, 2020
    Sayville, NY
    2001 290 Sundancer
    Twin 5.0L EFI w/Bravo II Drives
    I only pulled the wire off the sender, sprayed some contact cleaner on it. Wire brushed the post on the sending unit and put it back on. Once I saw a reading I figured the gauge is probably correct. Didn’t think about a dirty connection, maybe at the gauge, could result in a lower reading. I’ll remove the gauge panel and clean the connections. Then if it doesn’t change anything, I’ll try swapping the gauges. Thanks again Ron
     
  14. Shark

    Shark Active Member

    142
    Jun 16, 2020
    Sayville, NY
    2001 290 Sundancer
    Twin 5.0L EFI w/Bravo II Drives
    I might be able to do that, if I can get the sender out. I was barely able to reach it to clean the connection. Maybe if I really dive in there. That would take the guesswork out. This is my first real boat, so I’m learning a ton - I don’t know how some of you guys work on these engines! Lol
     
  15. Shark

    Shark Active Member

    142
    Jun 16, 2020
    Sayville, NY
    2001 290 Sundancer
    Twin 5.0L EFI w/Bravo II Drives
    Any advice or warnings about removing the panel with all the gauges on it? Looks simple enough - 10 screws...
     
  16. CaptRonn

    CaptRonn Well-Known Member

    May 25, 2016
    on a large body of water
    1999 Sea Ray 400 Sedan Bridge
    Convert fuel into noise
    Can you access from behind it? Otherwise it shouldn’t be difficult.

    How easy are the access to the senders on the engines?

    If sender access is easier, I would try that first.
     
  17. Shark

    Shark Active Member

    142
    Jun 16, 2020
    Sayville, NY
    2001 290 Sundancer
    Twin 5.0L EFI w/Bravo II Drives
    Only access is if I take the panel off. Doesn’t seem difficult. The senders are really hard to get to, especially the port engine.
     
  18. Shark

    Shark Active Member

    142
    Jun 16, 2020
    Sayville, NY
    2001 290 Sundancer
    Twin 5.0L EFI w/Bravo II Drives
    Ron - I Removed the panel with all the gauges in it. Was very brittle, corner piece even cracked off, but I can crazy glue it back on, no big deal. Cleaned up the connections, and tested the gauge, by jumping the sending stud to ground, turned engine on - gauge went to full 80 psi like I read that it’s supposed to.

    I still might try switching the gauges. I guess I can “switch” them electrically, right? If I make jumper wires, to connect the sending wires to the opposite gauges, and leave everything else as-is. That would basically be the same as physically moving the gauges (which would be a major job), right?
     
  19. Chip S

    Chip S Active Member

    316
    Jun 17, 2019
    Bordentown, NJ
    1993 Sea Ray 200 Overnighter
    1993 Mercury 150 hp Black Max Outboard
    Using jumper wires to switch the gauges would work. Since the gauge went to 80 psi when you grounded the sender wire the gauge is most likely working correctly. Corrosion on the sender terminal could affect the reading but if its still reading 20 psi after cleaning the terminals I'm guessing the problem is not the gauge.
     
    Shark and CaptRonn like this.
  20. scoflaw

    scoflaw Well-Known Member

    Aug 10, 2011
    cape cod mass, cape coral fl
    1999 Powerquest legend 260 sx
    502 mpi Bravo 1
    You might want to see if you actually do have oil pressure while you fiddle about.
     

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