18 hp briggs and stratton smoking

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Thread: 18 hp briggs and stratton smoking

  1. #1

    18 hp briggs and stratton smoking

    Hi, i have recently acquired a 1998 Argo bigfoot 6x6 with the 18 hp vanguard twin. I has only 490 hours on it.
    Haven't had it out for a real run yet just up and down the street. Pulled it out yesterday to get it ready to head to the bush and it started smoking, especially under load. Took the air filter box off and found it full of oil. My oil level was also high and had gas in it. drained the oil, changed the plugs and the air filter and put it back together. Oil level is staying ok so far but I have not taken it for a longer run down the road at all just running it in the driveway. I took the valve covers off to check things in there and found one of the rockers and push rods to be tight. The others moved freely and the rods could be turned easily by hand the one did not turn. I pulled the rod out, it is not bent. The rockers are also out of sync on that side, one is up and the other is down. Both on the front side are even? Could there be something stopping the rod from pushing down, and causing the oiling in the carb problem? I used to do most of my own mechanical work on my vehicles, but know very little about small engines. Thanks in advance for any help you can offer.

  2. #2
    Join Date
    Feb 2016
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    Mississippi
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    one is up and the other is down. Both on the front side are even
    This is normal operation, if I understand what you are asking. When the rocker arms are "up" the valve is closed. On the compression stroke, both the intake and exhaust valves are closed (thus both rocker arms are even); otherwise you will have no compression. The other cylinder will be on a different stroke (say intake for example) which requires the intake valve to be open and the exhaust valve to be closed. When a valve is closed there is a small amount of play (clearance) in the valve train which allows you to spin the push rod and will allow for some slack in the rocker arm.

    The smoking problem is likely not related to the valve train based on your description. If the oil level was too high and had gas in it you need to look for a problem with the carb (flooding and dumping fuel in the intake) or fuel pump if it has a vacuum driven pump. It can have an internal failure and gas can be drawn into the vacuum line and into the engine. You changed the oil and the oil level is good. I would clean the oil out of the intake, make sure the spark plugs are good and run it for a while. Keep an eye on the oil level. If the oil level stays where it should, but the engine keeps smoking, then dig further.

    What color was the smoke?

  3. #3
    Smoke was very white. When the Argo arrived it was out of gas they unfortunately ran it empty while loading it onto the trailer. I had a horrible time trying to get it started. to the extent that i added an electronic fuel pump inline by the tank to get the fuel up and get it started. I wired it to the key and plug it into the fuse box. as soon as it starts I unplug it from the fuse box. Could the running it empty have messed up the mechanical pump? And why would that cause the air filter an to fill up with oil? I was thinking it might be that crankcase ventilation box, but when i unhooked it from the air filter box it still smokes.
    Last edited by Trapper Dano; 04-23-2017 at 02:28 PM.

  4. #4
    Quote Originally Posted by Trapper Dano View Post
    Smoke was very white. When the Argo arrived it was out of gas they unfortunately ran it empty while loading it onto the trailer. I had a horrible time trying to get it started. to the extent that i added an electronic fuel pump inline by the tank to get the fuel up and get it started. I wired it to the key and plug it into the fuse box. as soon as it starts I unplug it from the fuse box. Could the running it empty have messed up the mechanical pump? And why would that cause the air filter an to fill up with oil? I was thinking it might be that crankcase ventilation box, but when i unhooked it from the air filter box it still smokes.
    I also tried pulling the plug wires now while it is running. when I pulled the plug wire on the back cylinder there was no difference hardly, but when i unplugged the front spark wire it really stumbled. I am thinking I definitely have some sort of problem in the back cylinder.

  5. #5
    Join Date
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    make sure the plug is good on the back cylinder and that it is firing through the plug. If so, then run a compression test and see what that cylinder reads. Check the compression on both cylinders for comparison purposes.

    There was another thread on here recently about rising oil level and oil in the breather of an engine. I'll try to find it and post it for you. I think it had some good instructions that may relate to your issue.

    Here's one link that discusses issues that may be helpful to you, although a different engine: http://www.6x6world.com/forums/engin...-fuel-oil.html
    Here's another link: http://www.6x6world.com/forums/engin...series-ii.html
    Last edited by dirtdobber; 04-23-2017 at 04:23 PM. Reason: Added links

  6. #6
    Plug is firing fine, a buddy is bringing me a compression tester tomorrow. Really starting to think head gasket. Thanks for the links I will check them out

  7. #7
    my friends response with the Briggs 18 horse is doing the same thing. wonder what it is.

  8. #8
    Join Date
    Oct 2007
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    statesville, north carolina
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    Quote Originally Posted by Trapper Dano View Post
    I also tried pulling the plug wires now while it is running. when I pulled the plug wire on the back cylinder there was no difference hardly, but when i unplugged the front spark wire it really stumbled. I am thinking I definitely have some sort of problem in the back cylinder.
    A bad diode is the cause of your problems. You will need to pull the flywheel cover from the engine and replace the wire that connects the 2 ignition coils for their kill circuit. When the diode goes bad you loose spark to one cylinder. That may also be the reason you had gas in the oil, if it was run like this for a long time all the unburned fuel in that cylinder was trying to push its way past the Rings
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  9. #9
    Join Date
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    Do your compression test, if it tests fine run it on high rpms for about 20 minutes and see if it clears as a wet muffler takes a while to clear. Check oil level, if OK rechange it as it will still be gas contaminated.


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    Joe Camel never does that.

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  10. #10
    Join Date
    Sep 2013
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    Waldo Wi
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    I sure would like to know how the gas got into the oil in the first place, a bad or leaking needle/seat will not do it unless it was gravity feed. I agree that the wet muffler is more than likely the reason for the white smoke

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