1999 Mercruiser 454 Horizon Inboard Valve seats

Discussion in 'Mechanic Recommendation Forum' started by West32, Oct 15, 2018.

  1. Espos4

    Espos4 Well-Known Member

    Jan 1, 2017
    Long Island NY
    2007 240 Sundeck
    350 MAG Bravo 3 W/DTS
    You may never know (he likely won’t show you) if the second piston rings were installed correctly. If they are installed incorrectly, they push oil toward the the combustion chamber instead of toward the crankcase.
     

    Attached Files:

  2. West32

    West32 Active Member SILVER Sponsor

    113
    May 24, 2017
    Racine
    1999 Sea Ray 370 EC Hardtop
    Raymarine Axiom Pro system, AP, Radar, VHF, Fox Marine Engine Monitor
    Twin Mercruiser 454 Horizon 380 hp
    Could be...Good to know
     
  3. PlayDate

    PlayDate Well-Known Member

    Dec 25, 2006
    Washington DC
    1994 370 Express Cruiser
    454 Mercruisers
    The bigger issue is that a leak down test would have shown blow by to the crankcase. Sure Mercruiser has different types of 7.4 rings but if you enter the engine number it tells you which rings to purchase. The big difference in Mercruiser piston rings is the depth of the ring grooves on the pistons.

    You can't put thick rings on shallow grooves....the pistons won't fit in the bore. You can put thin rings on deep grooves and the cylinder loses pressure and oil control. It sounds like he bought the wrong rings and charged you for them. Hopefully he picked up the tab for the second set.
     
    techmitch and joeyleggz like this.
  4. douglee25

    douglee25 Well-Known Member

    Jan 13, 2008
    Dallas, TX
    Cruisers 3575
    Twin 7.4l
    $1300 for rings? Holy fawk! I have never heard of 'marine rings'. I'd sure love to see the data on that one.
     
    joeyleggz and techmitch like this.
  5. scoflaw

    scoflaw Well-Known Member

    Aug 10, 2011
    cape cod mass, cape coral fl
    1999 Powerquest legend 260 sx
    502 mpi Bravo 1
    BS for sure...just doing a hone and rering myself. Nothing special there... no crazy price tag
     
    techmitch likes this.
  6. West32

    West32 Active Member SILVER Sponsor

    113
    May 24, 2017
    Racine
    1999 Sea Ray 370 EC Hardtop
    Raymarine Axiom Pro system, AP, Radar, VHF, Fox Marine Engine Monitor
    Twin Mercruiser 454 Horizon 380 hp
    So when I picked up the motor, the builder showed me the ring packages. The Rings are "Genuine GM parts and the Mercury part number sticker is over top of the GM Part number sticker. Mercury wants $162 per piston. A GM parts house wants $105 per piston. At least we know for the next one. The builder said the only difference is there is a special coating on the rings vs the standard rings he used the first time.
    I installed the motor yesterday, but our season is over here is Wisconsin. She'll sit until April now.
    Another note, the Timing gear set is no longer available from Mercury. The cross reference goes to a standard 454 gear set. The lower gear is about 3/16 of an inch longer than the stock unit. This ultimately pushed the harmonic balancer out which throws the belts out of alignment. The fix is to trim the balancer inner face down and everything lines up perfectly.
     
  7. West32

    West32 Active Member SILVER Sponsor

    113
    May 24, 2017
    Racine
    1999 Sea Ray 370 EC Hardtop
    Raymarine Axiom Pro system, AP, Radar, VHF, Fox Marine Engine Monitor
    Twin Mercruiser 454 Horizon 380 hp
    Well here we are 1 year later. Once again I am in the same situation - Low Power.
    At the end of last year, I got the engine back and installed it to let it sit all winter. This spring, I put the boat in the water, set the timing and away we went. The engine ran good in the spring of the year. As the year went on, I noticed a slight loss of power which got worse as the year went on. So after 200 hours of running this year, I did a compression check, 110 psi in every cylinder. I then did a leak down test and it was obvious the intake valves were not sealing. I decided to pull the heads and take a look. Almost all of the intake valves looked like this:

    20190806_212631.jpg

    I inspected the cam and everything looks great from what I can see. Pistons and Cylinders look fine. I didn't lose a drop of oil between oil changes.
    I took the Heads to another reputable builder. He still has them and he said he will have a diagnosis for me this week.

    What is going on here?????
     
  8. scoflaw

    scoflaw Well-Known Member

    Aug 10, 2011
    cape cod mass, cape coral fl
    1999 Powerquest legend 260 sx
    502 mpi Bravo 1
    Obviously running lean. Time to address your fuel delivery. Personally, I'd replace it all on a 20 year old boat.
     
  9. West32

    West32 Active Member SILVER Sponsor

    113
    May 24, 2017
    Racine
    1999 Sea Ray 370 EC Hardtop
    Raymarine Axiom Pro system, AP, Radar, VHF, Fox Marine Engine Monitor
    Twin Mercruiser 454 Horizon 380 hp
    So I think I finally got to the bottom of this. The builder machined the heads and took .005 off the mating surface. Then he ground the already worn valve seats and valves. Once all this is put back together and the rocker arms torqued to spec, the push rods are bottoming out the lifters. It's all about geometry. At cruising RPMS, the intake valves are not closing all the way and start to burn. The solution is to measure the engagement into the lifters and either shorten the valves or buy shorter push rods...it took many calls to many different mechanics and engine builders, but I think I have a reason and a solution to finally fix the problem for good...the Joy's of owning a boat...
     
  10. Espos4

    Espos4 Well-Known Member

    Jan 1, 2017
    Long Island NY
    2007 240 Sundeck
    350 MAG Bravo 3 W/DTS
    You can buy a single adjustable push rod and use that to measure exactly how long the correct push rod should be.

    Out of curiosity I would want to know just how much shorter the proper push rod should be.
     
  11. Rusted Nut

    Rusted Nut Member

    77
    Sep 21, 2016
    Lake Michigan
    1993 370DA
    Lots of engines
    Interesting thread. I hope you did new valve springs somewhere in this build.
     
  12. scoflaw

    scoflaw Well-Known Member

    Aug 10, 2011
    cape cod mass, cape coral fl
    1999 Powerquest legend 260 sx
    502 mpi Bravo 1
    That's not the right way to go about it, if your valve seats are too deep in the head, you replace the seat to bring the head back to spec. He should have picked up on this the first time assembling it.
     
  13. PlayDate

    PlayDate Well-Known Member

    Dec 25, 2006
    Washington DC
    1994 370 Express Cruiser
    454 Mercruisers

    I agree.....but I am also concerned about the existing heads and the heat marks. I would like to see that status of the metal when the reliefs are cut for the new valve seats. It takes a lot of heat to turn cast iron blue.
     
  14. scoflaw

    scoflaw Well-Known Member

    Aug 10, 2011
    cape cod mass, cape coral fl
    1999 Powerquest legend 260 sx
    502 mpi Bravo 1
    Yah, like he's running lean as well. Hope he's not using the same machine shop. Even when tightening down non adjustable rockers, it's real easy to tell if the lifter preload is correct. You hit zero lash and it should take about 3/4 of a turn when you hit your torque value.
     
  15. West32

    West32 Active Member SILVER Sponsor

    113
    May 24, 2017
    Racine
    1999 Sea Ray 370 EC Hardtop
    Raymarine Axiom Pro system, AP, Radar, VHF, Fox Marine Engine Monitor
    Twin Mercruiser 454 Horizon 380 hp
    Thanks for the Replies. I did not pull the motor this time. I only pulled the heads and took them to a different Motor Shop. This time, we are installing New Valves.
    As for running lean, this motor was using 1.4 to 1.8 GPH MORE fuel than my Starboard motor.
    In the pictures, the "Burn" Marks are mostly Carbon and clean up very easily. There was NO distortion of the metal. This engine runs between idle and 900 rpm 95% of the time. It has only run over 3700 for maybe 5 minutes total. On Plane, I run around 3400 RPM.
    The plan right now is to install the new valves, and install the heads, measure push rods and lifter preload and determine how long my push rods need to be..
     
  16. scoflaw

    scoflaw Well-Known Member

    Aug 10, 2011
    cape cod mass, cape coral fl
    1999 Powerquest legend 260 sx
    502 mpi Bravo 1
    Wrong approach brother, but best of luck though
     
  17. West32

    West32 Active Member SILVER Sponsor

    113
    May 24, 2017
    Racine
    1999 Sea Ray 370 EC Hardtop
    Raymarine Axiom Pro system, AP, Radar, VHF, Fox Marine Engine Monitor
    Twin Mercruiser 454 Horizon 380 hp
    Please let me know what the right approach should be then?
     
  18. scoflaw

    scoflaw Well-Known Member

    Aug 10, 2011
    cape cod mass, cape coral fl
    1999 Powerquest legend 260 sx
    502 mpi Bravo 1
    New valve seats to bring everything back to stock specs. Stock valves, same pushrods and just because the engine is using more gas, it isn't showing that in your combustion chamber shot, looks lean as hell.
     
    PlayDate likes this.
  19. douglee25

    douglee25 Well-Known Member

    Jan 13, 2008
    Dallas, TX
    Cruisers 3575
    Twin 7.4l
    And 0.005" isn't going to cause geometry issues with a stock engine. Either way, you can check it with a push rod checker and a lifter that's been modified to remove all slack inside. You can use a black marker or prussian blue on the valve stem to check the pattern.
     
  20. Wanderer 290

    Wanderer 290 Member

    90
    Jul 1, 2019
    01 sea ray 290 sundancer
    Twin 5.7 b3’s
    Oil in the intake runners and / or intake ports may be indicative of a bad intake gasket seal which would cause a lean burn condition.

    An engine with 3500 hours has probably been serviced to some degree in the past...

    If the heads have been milled before and again by you the geometry between the intake and heads may be off enough to affect the intake gasket’s ability to seal.
     

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