Exhaust valve pics/question

Discussion in 'Gas Engines/Drives/Transmissions/Props' started by Strecker25, Mar 12, 2018.

  1. Strecker25

    Strecker25 Well-Known Member SILVER Sponsor

    Nov 20, 2014
    Rochester, NY
    1998 290 Sundancer
    Twin 5.7EFI/Alphas, Kohler 4kw
    I had to pull the port exhaust from both motors in the fall to allow me to get to the remote oil hoses for replacement. I had taken pictures of the exhaust valves and one of them has what I would assume is oil on the valve and a little on the stem. I know the exhaust stem seals can be trohblesoon on these motors. They’re 5.7efi’s with about 750 hours on them. No issues running, but I will get a hint of smoke at startup if they’ve been sitting for a while. This pic was taken about 36 hours after the last run (which was on muffs with the fogging cocktail run through.

    Opinions? I don’t plan on necessarily doing anything about it now but I’m wondering if there’s some PM I should think about. Compression was outstanding on all 16 cyclinders when we bought her 3 years ago

    The first two are of what I would consider “normal” looking at the last one is the valve in question. Also, neither engine burns any oil and entire exhaust was replaced when I bought it

    680BCAE3-0784-4965-AB04-87CC8D4F0F4A.jpeg C6C2297E-CD58-49C0-8F2F-794BB89BB617.jpeg EE374A8E-AC6A-4CC1-A07C-913C08A24B27.jpeg
     
  2. Thornton69

    Thornton69 Member

    271
    Sep 15, 2014
    Northern BC
    1980 24.5' SR custom hardtop
    1984 18' Valco sled
    1984 20' Alicraft- sold
    5.7 260 Merc/ Bravo 2
    Evanrude 115/80 jet
    The wet residue looks like it came out of the cylinder. Is it the lowest on that bank? Probably your fogging cocktail. If you had "a problem" with seals you should see build up on the stems. Looks good for 750 hrs in my opinion. Some engine don't even use seals on their exhaust valves.
     
  3. Strecker25

    Strecker25 Well-Known Member SILVER Sponsor

    Nov 20, 2014
    Rochester, NY
    1998 290 Sundancer
    Twin 5.7EFI/Alphas, Kohler 4kw
    Thanks, to be honest I don’t remember what cylinder that was but based on the order of pics on my phone I do believe it was the furthest aft cylinder. I still have the one manifold off so I’ll take another look this weekend. Was also going to pull the plugs and get a quick look at those as well since I haven’t looked at them in about 160 hours of use since their replacement.
     
  4. scoflaw

    scoflaw Well-Known Member SILVER Sponsor

    Aug 10, 2011
    cape cod mass
    1999 Powerquest legend 260 sx
    502 mpi Bravo 1
    Change your valve seals, valve guide has probably got more clearance than it should.
     
  5. hottoddie

    hottoddie Well-Known Member

    Jan 11, 2012
    Boston/Cape Cod
    1986 Sea Ray 390 Express
    Garmin 4212 Chartplotter
    Garmin 24 HD Radar
    Garmin GSD 22 Sounder
    Garm
    454 Crusaders
    Most likely valve seals as they will dry out over several years. As long as you are not burning excessive oil and spark plugs look good I wouldn't worry about it.
     
  6. Strecker25

    Strecker25 Well-Known Member SILVER Sponsor

    Nov 20, 2014
    Rochester, NY
    1998 290 Sundancer
    Twin 5.7EFI/Alphas, Kohler 4kw
    Thanks all. I won't do them this year as we have a little one on the way and the season is about to get underway (hopefully)

    Since it runs fine I'll just keep an eye on the oil as usual and if I feel motivated over next winter I'll replace the seals. I found a bunch of info on how people do them with the heads still on. One guy said there is an air compressor attachment for the plug hole to keep the valves from dropping and that napa has a tool to compress the springs with the head still on.
     
  7. scoflaw

    scoflaw Well-Known Member SILVER Sponsor

    Aug 10, 2011
    cape cod mass
    1999 Powerquest legend 260 sx
    502 mpi Bravo 1
    This would be the time to do it while the exhaust is out of the way. Easy to do, and will only get worst
     
    Strecker25 likes this.
  8. hottoddie

    hottoddie Well-Known Member

    Jan 11, 2012
    Boston/Cape Cod
    1986 Sea Ray 390 Express
    Garmin 4212 Chartplotter
    Garmin 24 HD Radar
    Garmin GSD 22 Sounder
    Garm
    454 Crusaders
    I'm sure you tube has several videos on how to do the valve seals. Been many years since I've done a set but I could do them tomorrow if needed. Still have the tools in my box.
     
  9. Thornton69

    Thornton69 Member

    271
    Sep 15, 2014
    Northern BC
    1980 24.5' SR custom hardtop
    1984 18' Valco sled
    1984 20' Alicraft- sold
    5.7 260 Merc/ Bravo 2
    Evanrude 115/80 jet
    This port is the outlet of the cylinder and is pressurised for the most part. Warn exhaust guides and bad seals will deposit oil on the stem and downstream. You said it does not use oil. The oil dampness you see is your pics is from unburnt fogging. I would be happy with it and wouldn't waste any concern if it was mine.
     
  10. scoflaw

    scoflaw Well-Known Member SILVER Sponsor

    Aug 10, 2011
    cape cod mass
    1999 Powerquest legend 260 sx
    502 mpi Bravo 1
    "Hint of smoke at startup" Valve seals are shot
     
  11. hottoddie

    hottoddie Well-Known Member

    Jan 11, 2012
    Boston/Cape Cod
    1986 Sea Ray 390 Express
    Garmin 4212 Chartplotter
    Garmin 24 HD Radar
    Garmin GSD 22 Sounder
    Garm
    454 Crusaders
    No doubt. Judgement call as to whether or not to replace. If oil consumption is normal and plugs look good I would wait until such time as engine requires some other work. In Rochester NY the boat is most likely raw water cooled running in fresh water. Engines have a long life expectancy but may need some disassembly in the future anyway.
     
  12. CliffA

    CliffA Well-Known Member GOLD Sponsor

    Dec 29, 2009
    Lake Norman, NC
    2001 Sea Ray 340DA
    Name: 'Happy Place'
    4.5kW West. Generator
    Purchased Nov. 2014
    Fresh Water Use
    Twin Merc. 6.2L (MPI)
    Raw Water Cooled
    V-Drive Transmissions
    or he might be running an engine oil that is too thin but most likely worn valve seals are the problem....

    cliff
     
  13. Strecker25

    Strecker25 Well-Known Member SILVER Sponsor

    Nov 20, 2014
    Rochester, NY
    1998 290 Sundancer
    Twin 5.7EFI/Alphas, Kohler 4kw
    Quicksilver 25w-40, changed annually (typically about 60 hours), RWC, no oil consumption during the season, no issues with performance or any other engine related problems for the past 3 years.

    I'm going to pull the plugs for a close inspection and evaluate from there.
     
  14. hottoddie

    hottoddie Well-Known Member

    Jan 11, 2012
    Boston/Cape Cod
    1986 Sea Ray 390 Express
    Garmin 4212 Chartplotter
    Garmin 24 HD Radar
    Garmin GSD 22 Sounder
    Garm
    454 Crusaders
    I expect you will decide to leave well enough alone.
     
  15. BillK2632

    BillK2632 Well-Known Member SILVER Sponsor

    Jun 25, 2009
    Lake Norman, NC
    1999 185 Bowrider,
    Mercruiser 4.3, Alpha I
    I think I would leave well enough alone, not likely that at 750hrs your valve guides/seals are worn to the point of leaking oil into the cylinders. Me, I would do nothing at this point, it's not using oil and running fine and can you be sure the hint of smoke on startup is oil or a rich fuel mixture? I personally think the oil you are seeing is from the fogging oil. If it really bothered me, I would pull the manifold again in another 25hrs, not after fogging and have a look.

    I know we are all boat/motor geeks, (I have "fixed" too many things that didn't need fixing) but I would really try to resist any temptation to start tearing into a perfectly good running motor.
     
    Thornton69 likes this.

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