Mcculloch 4hp no start

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This topic contains 132 replies, has 16 voices, and was last updated by  joesnuffy 8 months ago.

Viewing 15 posts - 91 through 105 (of 133 total)

  • amuller
    US Member - 2 Years
    Replies: 788
    Topics: 125
    #75078

    I’m sorta confused here. Are the rusty reeds from the one you are trying to run? If so, and given the poor appearance of the rest of the motor, I’d suspect rusted bearings also and a need for a complete teardown. Also, rusty reeds will break….


    joesnuffy

    Replies: 285
    Topics: 20
    #75090

    I agree a total tear down may be next.

    I think the original reeds were the very dirty ones. I think the better looking set came off the donor motor.

    I don’t see rust on the crankshaft so I hope the bearings are good also but I do suspect worn rings on this motor. I think what were trying to do right now is get it to hit a lick which it has not. I think we have narrowed it down to the rings now if it does not hit a lick that is why I would like to know how much compression it has after a tad of oil is put into cylinder that and I read that particular motor needed a minimal of 90 lbs compression to run. A person would think 80lbs would do it but maybe not on this motor especially since its air cooled the rings could be just flat worn out.

    Hope that helps,
    Joe


    john8504
    US Member - 1 Year
    Replies: 117
    Topics: 18
    #75093

    That makes a good point. If it requires new rings then I can do it as long as I can get the parts. I’ll be bolting it back together tonight and see what happens afterwards.

    The reeds did have surface rust surrounding the contact points where it seats. The newer reeds are from the donor motor and where near perfect. A little steel wool made it just right.

    I took a peak at the needle bearings for the crank and they look fine from what I can see.

    Before I tore the motor down, I did have the psi at 85-86 from 80ish after putting a little oil in cylinder. It kept acting like it wanted to fire off but never did. After replacing reeds, maybe I’ll get what I need to have it fire. We shall see.


    joesnuffy

    Replies: 285
    Topics: 20
    #75115

    If you get it to fire up and run the compression may come up on the motor after some run time. You might try putting like a couple tablespoons of kerosene in the spark plug hole and turn the piston up like its facing the sky and let it sit a few days to free up the rings if they might be sticking then re-check compression before tearing it down.

    Joe


    amuller
    US Member - 2 Years
    Replies: 788
    Topics: 125
    #75126

    My opinion here would be to take them both apart and try to make one good one. But I suppose it depends on where you are trying to go with this.


    john8504
    US Member - 1 Year
    Replies: 117
    Topics: 18
    #75127

    If I can get it running, then I know that what I have works. Ag that point I’m going to take the lower plate off, that goes under points, and put it on mine since it is warped. One issue might be that I know that not all of the gaskets are available anymore. Overall yes I want to have one, good running, decent engine that I can say that I brought back from the grave. I have a few mcculloch chainsaws that I’ve done the same things with and had to do a complete tear down. They run like champs now. This motor is just being a little bit of a pain.

    Two questions. My tank has a dent on the side towards the opposite end of where the bung hole is. What is the easiest way to get this out. I’ve been thinking of using a air bladder and stuffing it in the tank, pump it up and try to push dent out. I’m also thinking this could break the seams. Secondly, what is correct lower unit oil to use? Will 80w90 be ok?


    john8504
    US Member - 1 Year
    Replies: 117
    Topics: 18
    #75134

    Well the new reeds definitely brought compression up over 90. The lowest picture is after reeds and the highest is after a couple drops on gear oil. I still have no fire. No burn. No pop. Nada. However I still have a flooding issue? I open fuel up about 1 full turn and I have fuel/carbon mixture dripping from lower shaft after cranking.

    What should my adjustment be on these two screws? Screw 1? Screw 2?

    Going to get someone to assist me in testing the distance the spark will jump and see what happens there.


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    retiredoz
    US Member - 1 Year
    Replies: 465
    Topics: 46
    #75135

    Set the high-speed (#1) 1 1/4 turn open from closed, # 2 at 1/2 – 3/4 turns open from closed. If you’re still using starting fluid into the carb, you need to open the choke – that flap across the front of the carb. But I’d go back to putting fuel (or starting fluid) directly into the cylinder and crank. If that doesn’t produce a pop, your timing is off or your spark went somewhere..
    The lower unit takes grease, not gear oil. Use whatever is commonly used in non-shift gear cases.


    john8504
    US Member - 1 Year
    Replies: 117
    Topics: 18
    #75136

    Hmm ok. I guest I have screw 2 open too far. I’ve got it 1.5 turns open and screw one I have at 1-1.5


    billw
    US Member - 1 Year
    Replies: 969
    Topics: 33
    #75139

    Have we been using the same spark plug the whole time? Sorry but I just don’t want to go back and read through the ten pages for that one.

    I would pull the plug, clean it, if it is new and ding it, if it is old. Make sure it is not FOULED by putting too much oil in the cylinder. Then I would DRAIN the gas from the carb and try to make it at least pop with starting fluid, or better, a small squirt of gas/oil mix in the carb. If no fire, do like retiredoz says and put a small amount in the cylinder; then see if THAT will fire. If not, recheck your spark. It must jump MINIMUM 3/16", not just across a normal plug gap.

    When you put it over slowly, with the spark plug OUT, does it make a noticeable, weasing sound, indicating that you have a little crank case compression? If not, you may have a massive lower crank seal leak, which could explain all the fuel/oil coming out of the leg, if it’s not flooding. When you get back to trying to start with a carb full of gas, pull the plug after cranking and smell it. Is it dry or does it smell like gas?


    joesnuffy

    Replies: 285
    Topics: 20
    #75182

    I think Bills advice is right on target. Do you have a different coil you could try? its possible the plug wire from the coil might be grounding out especially when you move the lever. Also are the flywheel magnets clean not rusted that can cause a weak spark rusty magnets on the flywheel clean them up with sand paper.

    I did find some pictures of a motor for sale like yours on ebay it helps me to understand how this motor is disassembled. The auction with the motor is here and the pics of power head can be seen. Whats interesting is the big plate bolted to motor looks to be an access plate or the motor may have been used for different applications like a lawn mower also but around plate it might be sucking air.

    https://www.ebay.com/itm/67-68-69-70-Se … 0507.m3226

    Joe

    ps a picture of flywheel like yours with rusty magnets.

    https://www.ebay.com/itm/67-68-69-70-Se … GQ&vxp=mtr

    also take a look at the rust on the ends of the coil laminates (I call them shoes) where the magnets go by them they need cleaning up with sand paper also being careful not to take off anything but the rust. That’s the kind of stuff that weakens spark.

    https://www.ebay.com/itm/67-68-69-70-Se … Id&vxp=mtr

    The coil also has 3 wires one goes to the points the other to ground. They also need to be clean and brigtned up even the grounding screw that holds wire down needs to be cleaned up. The actual spark plug wire also needs to be inspected to make sure its not cracked pulling the motor over and having someone looking in the dark might help to see if you have arcing from the plug wire to ground. Also that plug wire looks like it goes down through the metal might not hurt to make sure its insulated if its being squeezed through metal.


    john8504
    US Member - 1 Year
    Replies: 117
    Topics: 18
    #75185

    Here is a video of what my spark looks like. The new plug seems to be very erratic and the old ac plug seems to keep the spark together.


    john8504
    US Member - 1 Year
    Replies: 117
    Topics: 18
    #75187

    I did notice a small break in outer insulation at the boot. However, I can see that the inner wires are shielded inside the sparkplug wire.


    joesnuffy

    Replies: 285
    Topics: 20
    #75188

    The AC plug looks to be firing pretty well but you are moving the spark plug wire around while testing so it could be grounding.

    I also noticed when you changed plugs no spark or weak spark. I worked on a Johnson 9.9hp this winter for a friend down in florida no spark on the bottom cylinder turned out to be the coil was not grounded where the ground wire goes to ground. I had to clean up even the screw. With this engine not even hitting we need to get a good constant spark.

    Try taking that plug that’s not firing well and try and see if it will fire well using a lawnmower to test it if so then I think when you get it to fire with this outboard it will be a lot closer to hitting. 1. Clean the magnets on flywheel if their rusty, clean the laminate shoes, 2. Clean the ground wire, wire to points, make sure condenser is grounded well and possibly insulate your plug wire with something maybe a piece of hose or something then re-check your fire with the weak spark plug. An air cooled engine will not normally use a really hot plug so the fire has to be right and trying a lawnmower to see how it sparks that weaker plug might be helpful.

    I hope that helps,
    Joe

    Mumbles
    Mumbles
    Canada Member - 2 Years
    Replies: 3797
    Topics: 367
    #75190

    Has it been mentioned yet to check the condition of the wire clip inside the boot and its connection to the spark plug wires core?

    The wire clip terminal inside the boot is prone to corrosion from moisture and the pin on the clip can rust or corrode completely away causing a weak or no spark situation. Since the spark plug on this motor is exposed to the elements, I’d check it before going any further on this motor. If the second plug had a weak spark, it could be from the clip inside making an intermittent connection with the wires core and when the wire is bent to its installed position, there may be no electrical continuity at all, or in other words, no spark.


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