Engine oil leaking from timing chain cover and oil pan seal

Discussion in 'General Discussion' started by Hick, Feb 20, 2018.

  1. Hick

    Hick Member

    Sep 21, 2016
    1998 SeaRay Amberjack 370
    twin 7.4 Mercruiser crusaders
    The mechanic in the boatyard where I store my boat for the winter indicates there is oil leaking from the timing chain covers and the oil pan forward seals in both engines. The boat is a 1998 370 Express and the engines are the original 7.4 horizons. The mechanic says that both engines need to be removed from the boat in order to do this work, He is quoting 8 hours to remove and replace each engine, and 4 hours to remove and replace the the timing chain covers and oil pans on each engine. Does the removal of the engines and the hours seem reasonable?
  2. Boater420

    Boater420 Well-Known Member

    Mar 11, 2015
    Clearwater, FL
    '97 330 Sundancer
    Westerbeke 4.5BCG
    Twin Merc 454's
    I'd pay 4 hours to remove an engine and 4 hours to put it back. That's a tough job requiring specialized tools. However, the 4 hours to replace two gaskets seems high, but only by a few hours so I might be misreading your post.

    8 hrs to remove and replace port
    8 hours to remove and replace starboard
    4 hours to replace oil and timing cover gasket port
    4 hours to replace oil and timing cover gasket starboard

    8 hours to change 4 gaskets seems high to me if I am reading the post correctly.

    If I was doing this job, in my garage, with my own tools, I could have all the gaskets replaced on both engines in 4 hours provided there were no rusted nuts or broken bolts. So, your estimate only seems off by 4 hrs IMHO.
  3. Little Ducky

    Little Ducky Active Member

    Jun 5, 2017
    Chattanooga TN/Dickson TN
    1998 SeaRay 290 Sundancer
    Twin EFI 5.0L w/Alpha 1 drives
    How many hours on the engines?

    If you go through with it consider making a list of "while you're in there" while access is good to reduce additional labor costs.
  4. BillK2632

    BillK2632 Well-Known Member SILVER Sponsor

    Jun 25, 2009
    Lake Norman, NC
    1999 185 Bowrider,
    Mercruiser 4.3, Alpha I
    I can't speak so much for the time to remove the engines - sounds reasonable. But, I wouldn't jump too quick to fix it, I would asses exactly how much oil is leaking and from where. My 4.3 has a small oil leak around the same place - timing cover on 4.3's is known to leak oil where it meets up with the oil pan. The oil pan and timing cover share the same gasket, not sure if it is the same on the GM V8's. Mine was leaking (seeping really) when I bought it in 2006 with 125hrs, now 11yrs / 500hrs later the leak is no worse. It does not leak enough to even show on the dipstick, so I just wipe off the bottom of the motor occasionally and keep an absorber in the bilge. Not worth a $1000 repair that might not fix it and the process of pulling the engine and replacing it could cause other problems - engine alignment etc, plus the boat is 19yrs old. Now, in your case if the leak is getting worse, it might make sense to fix it. It does seem curious to me that all of a sudden both engines have exact same leak.
    Last edited: Feb 20, 2018
  5. scoflaw

    scoflaw Well-Known Member SILVER Sponsor

    Aug 10, 2011
    cape cod mass
    1999 Powerquest legend 260 sx
    502 mpi Bravo 1
    Agree with Bill, a little oil isn't a bad thing. With 20 year old engines the chance of things breaking on the R/R is high.

    Then it will be...Oh look at this and look at that. Could be a 5k repair.
  6. Espos4

    Espos4 Active Member

    Jan 1, 2017
    Long Island NY
    2007 240 Sundeck
    350 MAG Bravo 3 W/DTS
    If it were me With a 24 hour repair estimate, I would like the mechanic to point out exactly where the leak(s) are.

    Is this “weeping” where some debris clings to a moist area, a slow drip, or a steady stream of oil?

    Those gaskets typically don’t have pressurized oil forced upon them, and could possibly be sealed with silicone from the exterior, possibly.

    Not sure of the configuration of your particular engines, but do you have a PCV valve or just oil breather tubes from the valve covers to the flame arrestor?

    IF you have a PCV valve AND it is clogged, compression blow-by gasses could be pressurizing the crankcase and pushing oil out at that location.
    Last edited: Feb 20, 2018
  7. Hick

    Hick Member

    Sep 21, 2016
    1998 SeaRay Amberjack 370
    twin 7.4 Mercruiser crusaders
  8. Hick

    Hick Member

    Sep 21, 2016
    1998 SeaRay Amberjack 370
    twin 7.4 Mercruiser crusaders
    There are approx. 750 hours on the engines. Tks
  9. JVM225

    JVM225 Well-Known Member

    Apr 8, 2008
    Farmingdale, NY
    2002 410 Sundancer, Monaco Edition.
    3126 Cats.
    Sounds like the crank seals are leaking. Not unusual for a crank seal to start leaking, but rare for two motors to start leaking from the same place at the same time.
    8 hours to remove and reinstall each motor doesn’t seem exceptionally crazy. If he doesn’t encounter any problems it should take less time than that, but there are always problems so he’s probably allowing for that.
    4 hours to remove timing cover, replace seal and reinstall with new gaskets with the motor out of the boat is a generous amount of time, but not completely crazy considering all the stuff he has to remove to get to the timing cover and reinstall.
    I second making the list of things to change while the motors are out of the boat.
    Now is the time to do it.
  10. 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
    454 Crusaders
    Marine engines do not have PCV valves. They have oil breather tubes that vent excess crankcase fumes to the flame arrester to be inhaled thru the carburetor. I agree that minor oil leaks should not require vast amounts of $$ to repair. Keep a close eye on the leaks and keep absorbent pads under the engines.
  11. Bt Doctur

    Bt Doctur Well-Known Member

    Aug 21, 2010
    New Jersey
    Ex SRV 240 Weekender twin
    in between
    So your pulling the engines to replace parts without knowing where the leak is?
    Most inboard engines use the aluminum oil pan and tin timing cover.Hardly ever does the aluminum pan just start leaking.
    There is no need to remove the engine to change the timing cover seals IF there is enough room to use the harmonic balancer removal and istallation tool
  12. northern

    northern Well-Known Member

    Jan 17, 2007
    West coast Vancouver to Alaska
    380 Aft Cabin 1989 GPS and Charts by Nobeltec
    Twin 454 strait shaft
    If you do not leak more than a quart of oil between oil changes I would leave things. You can buy a lot of oil for what it will cost you fix the problem. Both my engines leak oil. I put an absorbent pad under each. It has oil on it every time I change oil but I do not add oil between oil changes.
  13. joeyleggz

    joeyleggz Member

    Jan 15, 2013
    long island
    current boat: 1997 sea ray 330 express cruiser
    twin 454's efi
    I have the smaller version of your boat but not smaller by much and If I’m not mistaken out engine rooms and everything else is identical I just re-powered both of my motors and pulled the entire deck apart to get to it if this guy is quoting eight hours to pull the motors and four hours for the actual repairs I think he is absolutely out of his mind that type of job would require your helm and seat passenger seat to be completely removed from the boat which means disconnect all the power lines waterlines Disconnect the lift Rams And then the hatch would have to be pushed up and secured as high as it could squeeze between the arch only at that point will you gain enough access to lift the motors away from the tranny’s up and out if he’s willing to stand behind those hours for the job I would say you hit the jackpot if you’re familiar with your bilge I can tell you that you most likely can do those repairs in the boat there is more than enough room to drop the pan on the motor and certainly enough room to sit in front of your engine and disassemble the front to get to the timing chain cover I would think hard about this repair if you were going to go through the effort of removing the engines that opens up 1 million other possible repairs you might want to consider while having the motors out of the boat like full access to the generator if anything major needs to be done transmissions ,shaft seals and a number of other repairs I’m sure this can turn into a major project for a small oil leak I have tons pictures if you want to see what I did so that you know what you’re getting involved and I can’t post them on here it will take forever to upload them so if you want PM me your number and I will send them over to you
  14. Jeepers

    Jeepers Member

    Sep 28, 2010
    Atlantic City,NJ
    1989 390ec
    First try to snug up the oil pan screws.
  15. 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
    454 Crusaders
    X2. This makes a lot of sense. Try the simple things first.
  16. JVM225

    JVM225 Well-Known Member

    Apr 8, 2008
    Farmingdale, NY
    2002 410 Sundancer, Monaco Edition.
    3126 Cats.
    Try putting some dye in the oil so you can trace where it’s coming from. You can probably borrow a light from your local auto mechanic or maybe even the auto parts store that sells the dye.
  17. fwebster

    fwebster Well-Known Member TECHNICAL Contributor PLATINUM Sponsor

    Oct 6, 2006
    Middle Tennessee ; Panama City Beach, FL
    1996 450DA
    3116 Caterpillars
    I am not familiar with the 7.4 powered 370EC..........every one sold here had Cat diesels. This boat has one of t he best bilges to work in and I'd want to verify that the front of the engine isn't accessible before buying into snatching both engines out to do a simple repair. I am, however, familiar with the 7.4 and oil leaks. Most of the time oil leaks from the timing cover come from the cover just rusting thru. In Mercruiser's infinite wisdom, they assemble the engines before painting them and that means the circulating pump covers and blocks the paint spray from ever getting to the timing cover. So for the last 20 years, the mild steel timing cover has been rusting away.

    Other work while this is going on should be to replace the circulating pumps....the labor is free since the OEM pumps have to be removed to get to the tining covers.......the accessory belts and any water hoses you can get to easier while this work is proceeding than after it ll goes back together.

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