oil blow by 1995 3.0 pontoon

Discussion in 'Gas Engines' started by David Kornegay, Jul 5, 2014.

  1. David Kornegay
    Joined: Jul 2014
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    David Kornegay New Member

    I have a 1995 harris float boat with a 3.0 mercruiser I bought it last year I have never had an inboard so I have questions and problems.the first is the I have oil blow by from the top of the valve gasket were on a car would be the pcv valve it has a 90┬░pointing at the flame arester it doesn't have the connector on the side of the carborator like a car motor so it is putting a fine oil mist in the motor compartment and has ruined one starter and yesterday the second alternator is there a filter I can buy and put on the 90 to catch the oil so it doesn't get into the motor compartment or any other suggestions thanks
     
  2. AndySGray
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    AndySGray Senior Member

    Somethings Missing

    There ought to be something attached - from the description there was once probably a hose which would lead over to the carb and someone has maybe changed carbs or broken a fitting and not re-instated the hose. Oil in the bilges is seriously frowned upon by the authorities and the fines when it gets pumped out into the aquatic environment should make it a priority to sort.

    Mercruiser had emmission control way before then so I don't think what you describe is normal - probably someone has mismatched components.

    Start with the motor Serial Number and look online for parts diagram or invest in the correct workshop manual.

    Or get a real good photo to post and the collective BD.net hive brain will sort it...
     
  3. powerabout
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    powerabout Senior Member

    regardless of where the hose is going oil doesn't come out of that, only vapour.
    If did just attach to the outside of the flame arrester.
    There is something seriously wrong with your engine
     
  4. David Kornegay
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    David Kornegay New Member

    I check the oil regular and it has never been low the oil mist is minimal but the guy that rebuilt my alternator said it had some oil in it and that was most likely what caused it to go out the starter also went out last year but last year I didn't know that the hose was supposed to be pointed at the arester I will take some pictures of it tomorrow
     
  5. gonzo
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    gonzo Senior Member

    The hose only goes to the side of the flame arrestor. There is no way the oil would damage the starter. It is sealed and the oil couldn't get into it. The alternator wouldn't have a problem with some oil mist either. Seems like you have an electrical problem. Are there two or one battery, is there a battery switch?
     
  6. David Kornegay
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    David Kornegay New Member

    Only one battery no switches the guy didn't rebuild the alternator whoever sends his parts never sent the right parts so he never rebuilt it he gave me a one wire alternator
     
  7. PAR
    Joined: Nov 2003
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    PAR Yacht Designer/Builder

    Welcome to the forum Dave.

    Gonzo is correct, on your Mercruiser, the PVC hose goes up to the side of the flame arrestor, often simply terminating at a sheet metal bracket. Under normal operation, the air being sucked into the arrestor, pulls blow by gases into the engine, to be re-consumed. Yes, the hose is pointed at the arrestor, usually with an angled "slash" cut, so it lies relatively flush.

    Check to see if the PVC is operating correctly. The quick check is to pull it off the valve cover and hose and shake it. If you hear a rattle, it's probably good, though still could be sticking. A squirt of carb cleaner usually will clean them up, so they don't stick. They also don't cost much (a couple of bucks) so replacement is good insurance.

    If you're getting a fair bit of smoke (more than a wisp) from the PVC hose, it's an indication of very worn parts inside the engine (rings, valve guides, etc.). Oil does come out of the PVC hose, but after it's condensed inside the hose and is sucked out by the running engine. This should amount to a few drips of oil at the end of the hose, as it rests against the arrestor. More than this suggests an issue.

    The starter is a few feet away from the PVC hose, so wouldn't be affected by excess oil from a worn engine or bad PVC system. The alternator also is a quite a distance, but a really worn engine can produce quite a bit of oil from the PVC system and this can get into the alternator, but it's still not going to hurt much. If the alternator is oil soaked, you'd have noticed lots of smoke and oil leaks all over the engine box and engine. This can cause electrical issues, mostly connection related.

    The typical course for you would be to first buy the appropriate manual for your engine/drive combination. This is the very first "part" you should buy for your boat, so you know what you have and what parts to order, when necessary. Next, clean the engine bay, box and related stuff, like wiring looms, hoses, etc. Spend a few hours with a bucket and a bottle of degreaser and get everything clean. Now start and run the engine up to temperature. Any leaks will become apparent and you can fix them too. Valve cover leaks are quite common with this engine, so exspect to see them. A new gasket on cleaned mating surfaces will fix this. The raw water impeller is considered a consumable part, so just replace it. They die regardless of use pretty quickly and only cost a few bucks.

    Once you've identified the leaks, run through the usual inspection process, looking at the hoses, belts, electrical connections, etc. Odds are you'll find a cracked wire or loose connector, cracked hoses and belts, etc. With the manual, run through the standard diagnostic procedures, so you can bring her into a good tune. This means a few replacement parts, like plugs, cap rotor, maybe plug wires, etc.
     
  8. AndySGray
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    AndySGray Senior Member

    What he said...

    And while buying those basic consumables Double Up - put a set onboard, carefully waterproofed in ziplocks, together with some basic tools wrapped in a lightly oiled rag and also ziplocked. It's good to know how to do basics and having the parts should something go wrong. I use an old 5 gallon plastic oil drum with the snap on type lid...
     
  9. powerabout
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    powerabout Senior Member

    theres, no PVC valve in that hose if it goes to the flame arrester.
    Perhaps the tube under the valve cover is missing.
    Its a rectangular sheet metal tube that goes from the valve cover then close to the head to help shed the oil from the blowby. Never seen one missing but that would certainly let more oil mist come up the tube than normal
     
  10. PAR
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    PAR Yacht Designer/Builder

    It depends on which one (3.0) they've used. The GM (181) marine comes both ways. My understanding of this boat is it's usually an outboard powered craft, so the idea of an inboard doesn't seem right. It's probably an outdrive, not an inboard. Mercruiser does have a GM 3.0 inboard, which is commonly called the bobtail, recognized by a high mount starter. This engine usually does have a PVC, but the I/O version most times doesn't. Photos would clear this up quickly enough.

    I'll ditto the comments about a set of spare parts, but will add a hunk of your kids chalk, placed in the parts/tool bag, will do as well in keeping them rust free and they will not be all slippery, when you eventually pull them out.
     
  11. powerabout
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    powerabout Senior Member

    Hi Par
    I thought only the euro delivered EFi ones had pcv set up (going as per a car into the inlet manifold)?
    Hard to get it to work when the vacuum is so low in a boat.
     

  12. PAR
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    PAR Yacht Designer/Builder

    I have seen bob tails with them installed, but I can't remember if I've seen one on an out drive. If they are, it's not common. I have a picture of a GM 181 bob tail with one installed somewhere around here.
     
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