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Boat engine question??

Discussion in 'The Lounge' started by alf4444, Jul 13, 2005.

  1. alf4444

    alf4444 1/2 ton status

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    I just picked up a 1967 17' fiberform with a merccruiser GM inline 6 model 160 hp, it was a freebie :D anyway the PO says the oil had water in it so I'm guessing head gasket right? anyway are auto applications for engine parts tha same as marine or can someone lead me to a few websites to educate me?
     
  2. Thunder

    Thunder 3/4 ton status

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    No. auto is not the same as marine. Marine parts are designed for heavy duity use an automobile will nver see. Parts like starters, alternators, carbs, fuel pumps. are sealed and designed not to emmit sparks or leak gas. So a fire does not start. Which can be a real bumer when you are miles off shore. So you should use marine parts if you can get them they really are not much more than auto parts if you buy them online.
    I buy from http://basicpower.com but therre are tons of other sites out there.
    Hopefully it is just a head gasket. if you live where it freezes it may be a cracked block/head. if the PO did not drain the block before winter.
     
  3. alf4444

    alf4444 1/2 ton status

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    thanks great link too although for now all I need is a head gasket which turns out to be the same as an auto:D
     
  4. Rob 85K5

    Rob 85K5 1/2 ton status GMOTM Winner

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    goto Boatered.com and go to the tech section and ask all your questions away.
     
  5. ryoken

    ryoken Puppy Fabricator Premium Member GMOTM Winner

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    do a compression or leakdown test... its more likely to be bad exhaust than a head gasket.. not saying it isn't a head gasket, just that more often than not its exhaust, especially if the boat has seen saltwater... water in your oil is very bad.. makes sure to change it and filter multiple times asap...

    a bad winterize is always a strong possibility too... as the others said, don't play when it comes to parts. stock merc stuff is the best.. auto parts are a big no no....
     
  6. alf4444

    alf4444 1/2 ton status

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    well i fired it up and it ran pretty good I need to pump the oil out though and get a good look at it. I t did come from washington so I guess it could have seen salt water. As for auto parts being a big no no how would the head gasket be any differant in a marine application?
     
  7. paulmoon

    paulmoon 1/2 ton status

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    I'm pretty sure the head gasket is the same as auto. It's mostly electrical,i.e. alternator, distrubitor, and also the carb. All are special to avoid gas fumes and spark from comming together in the bilge instead of the engine!! However, some gaskets are special because of the water environment. I have that engine in by cobalt. It works very well and many if not all parts are still easily found. Be very careful to winterize it correctly. Water left in the engine, exhaust/intake manifold or outdrive will very quickly crack all those parts! (that's how I got my cobalt cheap). Compression check,leak down are next I agree. However, I couldn't rule out a crack in the water jacket somewhere. I was amazed how much damage there was to the block on the boat I got. Good luck. Paul :waytogo:
     
  8. Thunder

    Thunder 3/4 ton status

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    As far as gaskets are concerned. if you dont want to buy Mercruiser. I would not use any automotive gasket except Felpro in a marine engine. Felpro is good stuff man. But will cost you bout the same as a mercruiser head gasket

    Ryoken knows his stuff. Check the exhaust too. Might want to do a compression test also.
     
  9. ryoken

    ryoken Puppy Fabricator Premium Member GMOTM Winner

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    thanks for the props Thunder... :D

    Allen... if it ran relatively smooth, thats even more of an indicator that it may be exhaust... is the boat rawwater or freshwater cooled?

    an automotive head gasket will work.. marine apps have coatings on the gaskets usually to help against salt corrosion and such tho... worth the extra couple bucks imo for Felpro's marine version...
     
  10. alf4444

    alf4444 1/2 ton status

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  11. MarcS

    MarcS 1/2 ton status

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    I agree, bet ya its the exhaust not a head gasket. The only way to tell is to do what Ryoken said. Compression and leakdown tests.

    Do not use auto parts on a boat. You will get stranded. Trust me, I learned the hard way.
     
  12. alf4444

    alf4444 1/2 ton status

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    any easy way to do a leakdown without a compressor? :confused:
     
  13. Roz

    Roz 1/2 ton status

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    uncle had a 18' (i think) starcraft and we used auto parts on it and it lasted for years with np. but that was freash water only and it did have open water cooling. do do the extra weather proofing on everything though and we used silicone(stay gel stuff) on the outside gaskets and wireing.
    dont know to much about the rig but buddy also put a 454 out of his powerwagon in a boat and it was awsome and sounded soooo cool. lasted couple years that i know of.
    i say make shure u auto bilge pump is good and if freah water it will be ok IMO
    salt i would go with marine stufff unless u freash water wash everything after use
     
  14. Roz

    Roz 1/2 ton status

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    foot pump? :D ive done it (im NOT a hick :haha: )
     
  15. Thunder

    Thunder 3/4 ton status

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    Raw water cooled is the stock cooling system that uses water pumped from the outside the boat (lake or ocean water) to circulate thru and cool the engine

    Freshwater or Closed System uses a system similar to a car with a heat exchanger instead of a radiator. Raw water is pumped thru a heat exchanger and it cools the engine coolant. The engine coolant is an antifreeze /water mix seperated from the lake/seawater. This system is great because yur not pumping saltwater or hard lake water thru youe engine. You dont get the corrosion and your gaskets dont get ate up.

    Your exhaust manifolds have water circulating thru them. There are 2 exhaust gaskets that can go bad and leak water back thru the engine. The manifold gasket, and the exhaust riser gaskets. The riser is a thing that looks like a upside down "U". right after the manifold. Its purpose it to keep water from backwashing into your cylinders when you suddeny throttle back. It is common for then to blow gaskets and leak back
     
  16. alf4444

    alf4444 1/2 ton status

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    :D AWESome that makes me feel better. Ita a raw watersystem so hopefully its just gaskets because a new exhaust is $400+ :eek1: I'm going to drain the oil 2night and check it out then I'll start with the exhaust manifold gasket first and see what happens. Thanks for all your help guys CK5 rules :bow: even when it comes to boat tech
     
  17. ryoken

    ryoken Puppy Fabricator Premium Member GMOTM Winner

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    want a job? :D :deal:
     
  18. ryoken

    ryoken Puppy Fabricator Premium Member GMOTM Winner

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    best way to check exhaust is to remove the 4 bolts from the riser to the manifold and take the riser off.. i can tell by feeling the risers when up to temp usually.. look down the manifold for signs of water infiltration. and up in the riser for a rust hole..

    exhaust failures are due to two possibilities. those gaskets failing.. once apart you may find that gasket surface heavily corroded, thus why they fail. if so you can and i suggest you mill them with a flat file.. many guys just Roloc the surfaces clean and think they're good.. i can't tell ya how many times i've gone back in on an exhaust someone did and correct the issue by milling the manifold... drag a file and you'll see right away.. usually the stud areas pull up and jacket walls become thin...

    the other reason is the riser or manifold itself failing... the risers will develop holes up in the top of them on the inside. not introducing the water farther down the exhaust. instead dumping it down the manifold..

    risers will fail more often then a manifold ( thankfully, risers run around $100 a piece, manifolds are about 300). most of the time you'll replace the riser, mill the manifold surface and put it back together... but its not uncommon in a salt boat, rawwater cooled for them both to be in pretty bad shape..

    make sure you use a gasket sealent on all sides of the riser gaskets if paper.. graphite gaskets go in dry... don't ever use silicone! something like permetex #300 or similar is good.. merc has had many emergency service bulletins on that gasket surface over the years..

    also you may be thrown on the riser gaskets because there are 4 water jackets but the gaskets usually only have one.. this is normal. it restricts flow and ensure the manifold has water..
     
  19. alf4444

    alf4444 1/2 ton status

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    I drained the oil and it definatley had water in it but for the hell of it I replaced the oil and fired it up it ran fine but seemed to get hot after 10 or so minutes of running I then shut it down and checked the oil so I definatly have a leak somewhere. Now before I going dumping too much money into this boat would you suggest changing manifold and head gaskets or just search for a new manifold, also would a manifold for a 165 work on a 160.. I found one for a 165 on ebay :D
     
  20. ryoken

    ryoken Puppy Fabricator Premium Member GMOTM Winner

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    first thing i would do is the compression test before i went and did a head gasket...

    i would pull the riser and inspect it.. if the manifold is questionable, you can pressure test it... can't test the riser, thats a visual inspection.. but yeah, those exhaust gaskets are more than likely the culprit...

    iirc, the 160 and 165 are not interchangable..
     

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