Mcculloch 4hp no start

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  • john8504


    Replies: 163
    Topics: 30
    #74904

    So here is what I have. Pic one is of points on cam when throttle off and engine at tdc. Picture Two is the throttle linkage itself. Picture three is of points on cam with throttle open to full and engine at tdc.

    I have tried to spray some starter fluid and crank now with throttle open and still not results.

    Let me know yalls thoughts.


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    retiredoz

    US Member - 1 Year
    Replies: 530
    Topics: 26
    #74912

    You might try it again without the choke ?


    billw

    US Member - 2 Years
    Replies: 1809
    Topics: 54
    #74918

    No need to be embarrassed about the mag lever. It only points out how tough this forum can be sometimes, to solve things. Because we all can’t be in the room to help, it’s almost like when Johnny Carson used to dress up with a turban, hold an envelope to his head and try to predict what was inside it. Sometimes it is almost telepathic, because the written word is just not enough. If a picture is worth a thousand words, BEING there must be worth a million words.

    If it still won’t go, my next move would be to pull the four screws behind the carb and have a look at the reed valves, to make sure they are not stuck open with debris. If the reeds are good, then I’d be squirting a a SMALL amount of gear oil into the cylinder to temporarily increase compression, and see if it will fart, then. By design, some engines will run great with 80 psi compression and others won’t even start. I don’t know about this particular model; although I BET 80 is good to go….(And I’d also recheck for a strong spark. Sometimes that can go away in the middle of things, because of a tiny piece of fuzz on the points or whatever. By the way, the spark should jump a measured 3/16" AT MINIMUM. 1/4" or more is the norm.)

    Long live American manufacturing!


    joesnuffy

    US Member - 1 Year
    Replies: 356
    Topics: 23
    #74925

    Bills advice is dead on and should help find the issue. Please take of pics of the reed valve assembly. You have pretty much ruled out timing as your issue. You can put a bolt or screw or something into the spark plug boot or where it connects to plug to see how far you can get the spark to jump to see how far it will jump. I did read that those particular motors need a minimum of 90lbs psi compression to run but I also think 80 should be in the ballpark. Is your compression gauge accurate? Putting some gear oil into the cylinder like bill said will bump up your compression and if the motor hits a lick then you know it will need new rings. The man that taught at the night school I went to told a story of being a kid and having to put a small amount of oil into the spark plug hole to get his 2 stroke Jacobsen (i think jacobsen) to start since it didn’t have enough compression then he could mow. You could try that first since motor is still together along with how far the spark is jumping before taking reed valves off.

    Once you try the oil trick to see if you can get it to hit re-check your compression with the gauge and let us know what psi is with the oil please.

    Joe

    ps the motor looks to be air cooled so the rings could in fact be worn out since the motor runs hotter than a water cooled engine and is mostly run in the summer months. I had a leaf blower that got like that once it would not start had fuel, spark, etc but not enough compression it needed a new ring or rings I had used it like 10 years at that point. If all else fails a person could pull the piston and carefully remove a ring and put it into cylinder and push it down like 1/2 inch using the piston and measure the gap in the rings using feeler gauges. Having said all that I still think 80psi should be good to go unless that number jumps dramatically once the oil is added thats why I would like to know what compression is after the oil is added.


    john8504


    Replies: 163
    Topics: 30
    #74927

    I’ll try that this morning. If the rings are work, I have no idea where I’m going to find rings for this thing. Most parts are obsolete and there is no reference that I have found for what rings to put on it. If I could get rings, then yes I would be putting those on myself.


    joesnuffy

    US Member - 1 Year
    Replies: 356
    Topics: 23
    #74930

    The guys here know where to get rings if it turns out you need them.

    I hate to keep harping on the exhaust being restricted but if everything else checks out to be o.k. it may need to be re-visited.

    I am guessing the motor also has an impeller to pump water to cool the exhaust. The impeller is in the 3rd picture it also helps to silence the exhaust adding the water to exhaust. Its the black rubber part in picture.

    MY QUESTION Could you tell me or show me a picture of what part bolts to the exhaust port in this 1st picture. Have you tried starting the motor briefly using starting fluid with that part off the motor?? That exhaust muffler part would take the bulk of the carbon build up since its the first place the exhaust goes. I have a 2 stroke yamaha golf cart it has a huge muffler they also become clogged and the fix without buying a new one is to build a fire then hang the muffler right above the hot coals and let the oil and carbon melt and run out of the muffler.

    If the exhaust is restricted then the engine can’t draw fuels in because it can’t push air out if that makes since. I am guessing that the part that bolts to the exhaust port here is not water cooled its the first place the exhaust goes and is vulnerable to carbon build up then the water is added thus surrounding it in the second picture to help keep it cool and reduce sound.

    Joe


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    amuller

    US Member - 1 Year
    Replies: 1041
    Topics: 161
    #74934

    I just skimmed through this thread and can understand your frustration. Chances are it’s something simple that you’re too close to easily see. Can you get somebody else to take a look at it with you? In general go back to fundamentals–if you have fuel, spark, and compression it should at least pop. Have you used an in line spark tester? It’s possible to have a bad plug wire or coil such that there is spark in one position but not in the installed position. Thinking spark because if you are priming it through the spark plug hole it should pop regardless of carb status. Also it seems that the carb was messed with previously to your getting it, suggesting perhaps a longstanding problem. Have you checked coil primary and secondary resistance with a meter? Checked point resistance? Checked for good grounding of stationary point> The plugs fire when the points open, which should be just a bit before top dead center with the lever in start position. This ignition is very similar to that used on Tecumseh/Sears lawn mower engines of pre-solid-state times. I’m not certain, but you might be able to harvest parts off an old lawn mower. (Timing will be fixed on a mower but coil, condenser, and points might fit.) If you are feeding it many doses of starting fluid, etc, make sure to give it shots of oil so as not to wash off the oil and score things. Good luck!


    joesnuffy

    US Member - 1 Year
    Replies: 356
    Topics: 23
    #74937

    I think that is a great idea if he possibly lives near one of our members here or knows someone that is good with outboard repair. Outboards are a bit different than other types of motors. I live in East TN Johnson City and would be glad to help if you live near me. Possibly if you mention where you live a member in your area would be willing to help out. I learned about outboards through necessity over the past 30 years because a new one cost so much now its more of an addiction lol.

    Hope that helps,
    Joe


    amuller

    US Member - 1 Year
    Replies: 1041
    Topics: 161
    #74954

    Also, if you are an AOMCI member you likely received a membership directory in the mail within the last couple of weeks.

    Alan


    john8504


    Replies: 163
    Topics: 30
    #74956

    I did join the site but I haven’t recieved anything in the mail. I live in Austin, tx.

    Update: joined and waiting on info packet.

    Going to rip into motor and since I have a donor motor, I’ll compare parts and see what might require replacement. First and foremost, the reeds. Pictures to follow.


    john8504


    Replies: 163
    Topics: 30
    #75026

    I’m going to add lots of pictures. I did notice that the reeds on motor were not in best of shape (in pictures) and the ones from the donor were in great shape…in swapped them out after putting a little steel wool to it. Also included is the makeshift gasket I put on since I couldn’t find another.


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    john8504


    Replies: 163
    Topics: 30
    #75027

    Picture of bad reeds


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    joesnuffy

    US Member - 1 Year
    Replies: 356
    Topics: 23
    #75036

    They look pretty clean now they did not before. I put locktite on those screws when I put reeds back on a motor. I usually use the red colored locktite on them to make sure screws don’t back off and get eaten by motor.

    One thing I do is take a flashlight and look to see if I can see light coming through the reeds once I got it all like I think it should be before putting it all back together.

    I see a muffler pipe attached to bottom of power head. Does any thing connect with where I have drawn a rectangle around the exhaust port????

    Joe


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    john8504


    Replies: 163
    Topics: 30
    #75040

    It was just a plate that directs the exhaust flow towards the baffle that I have pictures above.

    Yeah the reeds were pretty bad. Good idea on the flashlight. I’ll try that when I get home.


    joesnuffy

    US Member - 1 Year
    Replies: 356
    Topics: 23
    #75067

    I see what your saying. So the exhaust leaves exhaust port thru like a diverter then thru the baffle then exits thru the bottom of the outboard near the foot. All that is of course is clear and non-restricted I’m sure you have checked that out. No mud or nests down low where the exhaust leaves the foot? The reeds look good enough now to get the motor to hit. The ignition is firing and you know where to set your lever to make timing correct. Seems like it would hit at this point if you have adequate compression.

    Once you get it re-assembled let us know if you get it to hit if not have you tried a tad of gear oil in the cylinder yet? Also I would like to know what your compression gauge shows with the oil in cylinder for psi?

    Hope that helps,
    Joe

    ps glad you hear you joined the club and your waiting on info packet. Also your name should appear in red color now you have joined . You may have to contact the administrator on that. It also gives you access to more areas when you click on Board Index above.

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