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  1. #1
    Join Date
    Sep 2007
    Location
    Cincinnati, Ohio/Ohio River
    Boat
    Sea Ray.... Duh
    Details
    2003 320 Sundancer & 2012 185 Sport
    Engine(s)
    Twin 6.2L Close Cooled V-Drives & 3.0L Alpha 1
    Posts
    2,356

    7.4l 454 biii wot????

    I tried the search function with no luck and I'm trying to avoid a trip across town for my manuals. Does anyone have the WOT info for this set up handy? Reason for the inquiry is the last ride of the season had me about 1000 rpm higher than "normal". Normally cruised at 3600 rpm giving me about 28 mph... with a clean bottom at the end of the season I was at 4600 rpm for 28 mph. The engine sounded the same as normal, not over revving just the tach seemed off. I had Sea Ray check it during winterization with no definitive diagnosis. Any thoughts?
    Current boat 2003 320 DA Jimi Thing III
    6.2L Close Cooled w/ V-Drives and 2012 185 Sport WEE RAY
    Previous boats
    2001 280 DA (sold), 1995 250 DA (sold), 1993 230 DA (sold)
    Lt. Dan

  2. #2
    Join Date
    Jul 2009
    Location
    Annapolis, MD
    Boat
    Sea Ray
    Details
    1997 Sea Ray 270 Sundancer, 8.1L Repower
    Engine(s)
    8.1L Repower w/Bravo III
    Posts
    73

    Re: 7.4l 454 biii wot????

    For the 1997 7.4L 300 & 330HP WOT is 4600.

    Some of this info is on SeaRay.com
    No Name Sea Ray
    1997 Sea Ray 270 Sundancer, 8.1L Repower
    Annapolis, MD

  3. #3
    Join Date
    Nov 2009
    Location
    Bartlett Lake AZ
    Boat
    Chaparral
    Details
    2012 Chaparral 267 SSX For Sale
    Engine(s)
    8.1 400HP Volvo DP, Vacuflush Head, Garmin 536 GPS, Lenco Trim Tabs with Indicator Lights
    Posts
    1,480

    Re: 7.4l 454 biii wot????

    Did you measure your speed with GPS or your speedometer? My old Mariah had the same engine, drive and length as your boat and at 3,600 RPM the speed was around 28 using GPS. The speedometer didn't work probably due to the sensor on the drive being clogged. Also when is the last time your had your engine alignment checked. That engine with a Bravo III drive is prone to coupler wear. I know first hand about this because I had to pay CSR $1,500 to replace it when I traded in my Mariah.
    Last edited by 320Bob; 11-05-2009 at 02:32 PM.

    Previous Boats:
    2006 Sea Ray 320 traded down to 267 SSX
    1999 28' Mariah Z280 traded up to 320
    2002 24' VIP Voyager 2402 traded up to Z280

  4. #4
    Join Date
    Apr 2009
    Location
    PA
    Boat
    Sea Ray
    Details
    1999 260DA ShoreLand'r Galvanized
    Engine(s)
    5.7L EFI Bravo III
    Posts
    8,780

    Re: 7.4l 454 biii wot????

    Do you know if they checked the selector switch on the back of the tach? It can be set for 4cyl, 6cyl or 8cyl. "Exercising" the switch back and forth usually does the trick.
    Dennis
    1999 260DA 5.7L EFI B3
    2000 ShoreLand'r
    Past & Other Current Boats: Not enough room!
    "Exceeding your expectations since 1936"

  5. #5
    Join Date
    May 2008
    Location
    Knoxville TN
    Boat
    Sea Ray
    Details
    2000 SeaRay Sundancer 270
    Engine(s)
    7.4l Mercruiser w/ Bravo III
    Posts
    1,013

    Re: 7.4l 454 biii wot????

    I am not sure how much work you do on your own boat but if you do a decent amount the mercruiser scan tool is a great investment and will give you an accurate RPM reading

    http://www.rinda.com/marine/marine.htm

    I have the same set up by the way and have had no problems with coupler. Fingers crossed....

    John
    2000 Sea Ray 270, 7.4L Mercruiser Bravo 3
    1995 Cobalt 200, 5.0L Volvo Duoprop
    Fort Loudoun Lake, Knoxville, TN


  6. #6
    Join Date
    Nov 2007
    Location
    N. Wisconsin/Lk Superior
    Boat
    2005 SeaRay 280DA
    Details
    Eagle Tri-axle trailer
    Engine(s)
    T5.0MPI 260HP B3 Drives/ratio 2:20/24P props
    Posts
    3,953

    Re: 7.4l 454 biii wot????

    Quote Originally Posted by 320Bob View Post
    Did you measure your speed with GPS or your speedometer? My old Mariah had the same engine, drive and length as your boat and at 3,600 RPM the speed was around 28 using GPS. The speedometer didn't work probably due to the sensor on the drive being clogged. Also when is the last time your had your engine alignment checked. That engine with a Bravo III drive is prone to coupler wear. I know first hand about this because I had to pay CSR $1,500 to replace it when I traded in my Mariah.
    Why would the Bravo 3 drive be "prone" to coupler wear?
    2005 280DA T-5.0MPI, 260hp, B3, current boat
    2004 270SD 496HO, 425hp, B3
    2004 200BR 5.0MPI, 260hp, Alpha 1

    Never take a sleeping pill and laxative at the same time

  7. #7
    Join Date
    Nov 2009
    Location
    Bartlett Lake AZ
    Boat
    Chaparral
    Details
    2012 Chaparral 267 SSX For Sale
    Engine(s)
    8.1 400HP Volvo DP, Vacuflush Head, Garmin 536 GPS, Lenco Trim Tabs with Indicator Lights
    Posts
    1,480

    Re: 7.4l 454 biii wot????

    Quote Originally Posted by Woody View Post
    Why would the Bravo 3 drive be "prone" to coupler wear?
    I got this from Chicago Sea Ray who told me they have replaced between 30-50 couplers this year including the one on my old Mariah. First the 7.4L is the old Chevy big block with a lot of torque which puts more stress on the coupler and I believe makes it more prone to go out of alignment. Second factory coupler is made out of aluminum while the Bravo III shaft into the coupler is steel. Steel is harder than aluminum.

    They pulled the BIII drive to expose the coupler and showed me the alignment tool from Mercury they use to check engine alignment. It should slide in with no binding but on my boat it took a lot of effort to shove it in. When removed, I could see scoring in the grease on one side indicating the engine was not aligned. Then they shined a flashlight in the coupler opening and I could see that the splines had been worn to a point instead of being flat indicating wear caused by misalignment. Since the coupler is bolted to the engine fly wheel, the whole engine has to be pulled to replace it which is why it cost me $1,500. I bought the boat used from Spring Brook Marina with 323 hours on it. I put another 16 on it which was not enough to wear the coupler so the engine was out of alignment long before I got the boat. The Mercury manual for that engine and drive recommends the engine alignment be checked every 100 hours which obviously Spring Brook did not do before selling me the boat which was theirs not a brokerage boat.

    Previous Boats:
    2006 Sea Ray 320 traded down to 267 SSX
    1999 28' Mariah Z280 traded up to 320
    2002 24' VIP Voyager 2402 traded up to Z280

  8. #8
    Join Date
    Sep 2007
    Location
    Cincinnati, Ohio/Ohio River
    Boat
    Sea Ray.... Duh
    Details
    2003 320 Sundancer & 2012 185 Sport
    Engine(s)
    Twin 6.2L Close Cooled V-Drives & 3.0L Alpha 1
    Posts
    2,356

    Re: 7.4l 454 biii wot????

    Quote Originally Posted by 320Bob View Post
    I got this from Chicago Sea Ray who told me they have replaced between 30-50 couplers this year including the one on my old Mariah. First the 7.4L is the old Chevy big block with a lot of torque which puts more stress on the coupler and I believe makes it more prone to go out of alignment. Second factory coupler is made out of aluminum while the Bravo III shaft into the coupler is steel. Steel is harder than aluminum.

    They pulled the BIII drive to expose the coupler and showed me the alignment tool from Mercury they use to check engine alignment. It should slide in with no binding but on my boat it took a lot of effort to shove it in. When removed, I could see scoring in the grease on one side indicating the engine was not aligned. Then they shined a flashlight in the coupler opening and I could see that the splines had been worn to a point instead of being flat indicating wear caused by misalignment. Since the coupler is bolted to the engine fly wheel, the whole engine has to be pulled to replace it which is why it cost me $1,500. I bought the boat used from Spring Brook Marina with 323 hours on it. I put another 16 on it which was not enough to wear the coupler so the engine was out of alignment long before I got the boat. The Mercury manual for that engine and drive recommends the engine alignment be checked every 100 hours which obviously Spring Brook did not do before selling me the boat which was theirs not a brokerage boat.

    Good information but would that cause my boat to indicate higher RPM's with reduced speed? As i said the "harmonics" sounded to be normal for the indicated speed, but the tachometer was indicating 1000 RPM's more than speed and sound would have suggested. As for previous questions, the speed is dash speedo read, not GPS BUT...... despite my inherent distrust for the pito-pushed speedometer I am leaning towards trusting it in this rare instance
    Current boat 2003 320 DA Jimi Thing III
    6.2L Close Cooled w/ V-Drives and 2012 185 Sport WEE RAY
    Previous boats
    2001 280 DA (sold), 1995 250 DA (sold), 1993 230 DA (sold)
    Lt. Dan

  9. #9
    Join Date
    Nov 2009
    Location
    Bartlett Lake AZ
    Boat
    Chaparral
    Details
    2012 Chaparral 267 SSX For Sale
    Engine(s)
    8.1 400HP Volvo DP, Vacuflush Head, Garmin 536 GPS, Lenco Trim Tabs with Indicator Lights
    Posts
    1,480

    Re: 7.4l 454 biii wot????

    dpvandy01,
    I am pretty sure the coupler was not causing your tachometer problem but I thought you might still have it in the shop so an alignment check could be done if you haven't had one in the last 100 hours.

    Previous Boats:
    2006 Sea Ray 320 traded down to 267 SSX
    1999 28' Mariah Z280 traded up to 320
    2002 24' VIP Voyager 2402 traded up to Z280

  10. #10
    Join Date
    May 2008
    Location
    Knoxville TN
    Boat
    Sea Ray
    Details
    2000 SeaRay Sundancer 270
    Engine(s)
    7.4l Mercruiser w/ Bravo III
    Posts
    1,013

    Re: 7.4l 454 biii wot????

    Yeah I guess we missed giving you an answer assuming the tach is correct. If bottom is clean then it would have to be slip of the propellar or a significant change in weight. I am at a loss to explain it mechanically but I'm not that good at some mechanicals.

    John
    2000 Sea Ray 270, 7.4L Mercruiser Bravo 3
    1995 Cobalt 200, 5.0L Volvo Duoprop
    Fort Loudoun Lake, Knoxville, TN


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