8.1 Questions

Discussion in 'Newbie Lounge - NEW' started by crm-114, Oct 9, 2017.

  1. crm-114

    crm-114 New Member

    8
    Mar 22, 2016
    NC
    2013 Bayliner 255CR
    5.0MPI BIII
    Hi Folks,

    The wife and I are looking at several searays ranging from 2004 to 2011, most all of these boats have 8.1 Mercruiser engines. From what I understand they are a pretty good engine but im a bit confused about a few things.

    -How are the manifolds cooled, are they cooled with raw water or cooled with the antifreeze used in the block?
    -Since the elbows are stainless how long do they last?
    -Does the vessel view system report any diagnostic information or would I still need a scan tool if the horn warning system went off?

    Thanks
     
  2. paulswagelock

    paulswagelock Well-Known Member

    Oct 25, 2010
    pa
    2018 SDX 270 OB 300 Verado
    Verado 300
    Manifolds are cooled with raw water.
    Vessel view should show codes but not all diagnostics like a scan tool would.
    Freshwater boater so not sure on the elbow life.
     
  3. outlaw32

    outlaw32 Member SILVER Sponsor

    71
    Mar 15, 2014
    St Petersburg Fl
    340
    496 V drives
    Elbows are Stainless. I have a 2003 and just replaced my manifolds. risers looked new on inside. My manifolds were aluminum.
     
  4. crm-114

    crm-114 New Member

    8
    Mar 22, 2016
    NC
    2013 Bayliner 255CR
    5.0MPI BIII
    OK, so this is going to be like my last boat with a 5.0 MPI. Every 5 years spend the money on changing the manifolds and risers or in the 8.1's case the elbow.
     
  5. carterchapman

    carterchapman Well-Known Member TECHNICAL Contributor SILVER Sponsor

    Mar 25, 2008
    Lake Chickamauga/Marietta, GA/Ft. Myers, FL
    2006 Sea Ray 58 DB
    MAN CRM V8-900s, Twin Disc Drives; Onan 21.5 Generator
    OPE (set code prefix) - As outlaw mentioned aluminum manifolds were used into late '04/early '05. They might still be good on a 100% FW boat might still have them - but have those changed immediately.

    Correct CRM114 code prefix - right?
     
  6. crm-114

    crm-114 New Member

    8
    Mar 22, 2016
    NC
    2013 Bayliner 255CR
    5.0MPI BIII
    Its only the best movie ever, made me believe the Russians were putting stuff in my water.
     
  7. carterchapman

    carterchapman Well-Known Member TECHNICAL Contributor SILVER Sponsor

    Mar 25, 2008
    Lake Chickamauga/Marietta, GA/Ft. Myers, FL
    2006 Sea Ray 58 DB
    MAN CRM V8-900s, Twin Disc Drives; Onan 21.5 Generator
    Can't make that up! Great movie. OK, for the rest of you if you read on, you've got to watch it - Dr. Strangelove.



    My favorite is "who is flying" at 2:12 - nobody!!
     
  8. rondds

    rondds Well-Known Member SILVER Sponsor

    Oct 3, 2006
    Jersey Shore
    2001 380DA
    Merc 8.1s (2008)...Hurth ZF 63 V-drives...WB 7.0 BCGD (2013), Garmin 8208 & 740 MFDs, GMR 24xHD dome
    Elbows are stainless and last. Riser blocks are very expensive (though not all boats require them) and mainfolds are crazy expensive.

    My engines spent 4 years in salty water (Long Island) and 5 in brackish NJ river water. There was enough rust flaking off after 9 seasons that the pieces clogged up my dripless shaft log nipple and melted the whole dripless on one engine. I'd say 7 seasons on salt, 10+ in brackish is what you can expect.

    Bring a magnet with you when you go look at a boat to see if the manifolds are aluminum. Aluminum absolutely must be replaced if you plan on boating in salt water.

    The exhaust system design of these engines is far better than that of the 7.4/454s. Most 454s die a death from failure of the gasket btwn the exhaust manifold and the elbow/riser. Unbeknownst to the captain, water or coolant seeps into the exhaust gas passages and into the cylinder heads and valve train - over time the valve train can rust or, worse yet, the water gets into the cylinders and hydrolock results.

    The 8.1s has a dry joint, between the manifold and riser/elbow assembly, which pretty much eliminates this possibility. The price you pay is raw-water cooled manifolds which won't last as long as coolant-cooled manifolds. I've had both systems and would take the 8.1s over the 7.4s any day.
     
  9. Gary B

    Gary B Member

    152
    May 20, 2015
    Long Island
    2007 52 Sedan Bridge
    Cummins QSM 11
    We had 2006 8.1's used in salt water for 8 years and about 400 hours before we moved up to a diesel powered boat.

    The 8.1 engine is terrific BUT we had to replace the exhaust manifolds (not unexpected after 7 years in salt water), manifold temperature sensors, IAC (Idle Air Control sensors), the fuel coolers (twice) and water pumps. The next owner changed the oil coolers and had to the replace the water pumps (Mercury) again after 3 seasons of use.

    Our experience was the components Mercury used clearly are not designed to stand the test of time especially in salt water.

    I am not sure if Volvo or other gas engine manufacturers would be much different
     
  10. billm1104

    billm1104 New Member

    10
    Oct 14, 2017
    Boatless. Should be changed shortly
    boatless
    Greeaaaaattttt....I'm in the process of buying an '01 380 with the 454's. Now I'm worried. The motors only have 260 hours on them. Did you buy reman 8.1s? Afraid to ask what they cost!
     
  11. LG111

    LG111 Active Member

    382
    Jan 4, 2015
    NW
    410
    8.1
    454's with log exhaust, I'd walk. If lift buckets then your probably okay. 2001 is when lift buckets became standard.

    454 High Output are the concern. The cam in these created back pressure and vacuumed water vapor back into the cylinders during low rpms.
     
  12. rondds

    rondds Well-Known Member SILVER Sponsor

    Oct 3, 2006
    Jersey Shore
    2001 380DA
    Merc 8.1s (2008)...Hurth ZF 63 V-drives...WB 7.0 BCGD (2013), Garmin 8208 & 740 MFDs, GMR 24xHD dome
    I agree with LG111. If the muffler system is changed to water-lift and the horizontal logs are gone you should be good. However you may want to do a compression check. It's not that difficult bc there's plenty of room to roam in the engine room on the 380.

    I bought this boat in early 2013. It was repowered before the 2008 season so I didn't bear the cost and I couldn't tell you what the cost was.

    Good luck with the purchase!
     
  13. billm1104

    billm1104 New Member

    10
    Oct 14, 2017
    Boatless. Should be changed shortly
    boatless
    Here's a pic of the engines, so please tell me if they're log exhausts and HO. Survey is being done 11/8. Sorry to OP. I don't mean to hijack this thread
    sundancer 380 18.jpg
     
  14. Strecker25

    Strecker25 Well-Known Member SILVER Sponsor

    Nov 20, 2014
    Rochester, NY
    1998 290 Sundancer
    Twin 5.7EFI/Alphas, Kohler 4kw
    Those are the water lift mufflers, so you're on the right track. I'd still have a compression test done to be sure
     
  15. kap2

    kap2 Member SILVER Sponsor

    148
    Oct 28, 2013
    Rhode Island
    370 Sundancer 1998
    Twin 7.4L Mercruiser V-drive
    billm those are the Horizon HO engines with the waterlift mufflers. Good to go!
     
    billm1104 likes this.
  16. billm1104

    billm1104 New Member

    10
    Oct 14, 2017
    Boatless. Should be changed shortly
    boatless
    Thanks Strecker25. The engines only have 260 hours so I don't know if that's enough time on them to show anything but I will talk to the surveyor about it.
     
  17. billm1104

    billm1104 New Member

    10
    Oct 14, 2017
    Boatless. Should be changed shortly
    boatless
    Thanks Ken! Where in RI are you. I have lots of friends in the So. Kingston/Charlestown area.
     
  18. kap2

    kap2 Member SILVER Sponsor

    148
    Oct 28, 2013
    Rhode Island
    370 Sundancer 1998
    Twin 7.4L Mercruiser V-drive
    billm - I'm in Bristol. RI is a great place for boating!
     
    billm1104 likes this.
  19. billm1104

    billm1104 New Member

    10
    Oct 14, 2017
    Boatless. Should be changed shortly
    boatless
    It sure is!! I hope to be docking in Clinton, CT but will spend most of my time motoring out to RI. I would dock there but just too far of a drive to work (New Haven).
     
  20. Strecker25

    Strecker25 Well-Known Member SILVER Sponsor

    Nov 20, 2014
    Rochester, NY
    1998 290 Sundancer
    Twin 5.7EFI/Alphas, Kohler 4kw
    Valvetrain or other ingestion problems would show after that amount of usage. It’s more about the time sitting than running as that’s when the moisture does it’s damage. If you’re really concerned a mechanic may have a small scope camera that they could get a look at the valves through the exhaust ports in the head and inspect for rust. Honestly I’m sure you’re fine especially if those mufflers were there from the factory n
     

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