Engine Smoking and Burning Oil

Discussion in 'Mechanic and Repair' started by vball2116, Jun 15, 2005.

  1. vball2116

    vball2116 LawnSite Member
    Posts: 54

    Hey everyone. I have a mower that I got from my uncle this season and it smokes everytime that I use it. I start the mower and it runs alright, but within 5 minutes from when I start it, it starts smoking. I am able to finish the lawn, but it smokes a lot. I just changed the oil and as soon as I cut it I checked the oil and it looked almost black. What could the problem be? The motor that I have is a 3.5 HP Max Briggs & Stratton Magnetron engine. I will post a picture of the engine and the mower. I will appreciate any help that you may have for me.



  2. rlpenny

    rlpenny LawnSite Member
    Posts: 16

    Does it cut well in thick grass or seem to lose power when the going gets tough? Sounds like worn rings to me but I'd defer to a real mechanic.
  3. Guthrie&Co

    Guthrie&Co LawnSite Senior Member
    from nc
    Posts: 784

    yeap. sounds like you have a set of worn rings.
  4. Restrorob

    Restrorob LawnSite Fanatic
    Posts: 11,023

    If this is black smoke you see,The carb. needs to be cleaned and a rebuild kit installed. If its blue smoke,The engine should be disassembled and the cylinder bore checked for wear and out of roundness with a inside micrometer to determain if it can be re-ringed standard or should be bored over-size,and also check the valves and guides for wear.The crankshaft should be checked with a micrometer also for wear and out of roundness.Just by looking at the pics. I can tell thats a older unit and probably has quite a few hours on it,If it were me I'd go here ( smallenginewarehouse.com ) and order a replacement engine and forget about the rebuild process, Just ckeck the size of your crankshaft and compair. I seen three candidates for around 75.00
    Maybe this is of some help.
  5. vball2116

    vball2116 LawnSite Member
    Posts: 54

    Hey guys thanks for the replies. The mower is very old because I went on Briggs and Stratton's website last night and the manual for my mower is from 1989 on their website.

  6. sdwally

    sdwally LawnSite Senior Member
    Posts: 385

    If you are just using this mower on occassion, ie mowing your personal yard, you can get a little more life out of the mower. This is not a fix, but will extend your usage before rebuilding, replacing engine, or scrapping the mower. I believe its Kendall Motor Oil that has oil called Nitro 90 or 80, its a thick motor oil that will stop the smoking. Its just too thick to get by the worn rings. Have used on engines just to get a little more life out of em, with out the expense of a rebuild or engine replacement.

    As I said above this is not a fix, just a temporary option till the motor gets worse.
  7. Lawn Masters

    Lawn Masters LawnSite Senior Member
    Posts: 850

    Yep, this is the most common indicator of worn piston rings, or possibly piston/cylinder damage I can imagine.
    I once pulled a piston from a mower that looked like it came from a 2 stroke run on straight gas. THAT was a classic piece of crap not worth fixing.

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