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briggs 20 hp question

Discussion in 'Mechanic and Repair' started by fga, Sep 12, 2006.

  1. fga

    fga LawnSite Silver Member
    Messages: 2,449

    i have a 20 hp B&S I/C Diamond engine, 2 cylinder.

    if i were to take-out both plugs, how free should the engine spin, if i spin it maunally?
  2. Restrorob

    Restrorob LawnSite Fanatic
    Messages: 11,029

    Should be able to lay the palm of one hand in the center of the grass screen and spin it pretty easily as long as the belts are disengaged.
  3. fga

    fga LawnSite Silver Member
    Messages: 2,449

    great, maybe you can help me. i sold a 4 year old lawntractor to some guy, had the above engine on it. it was hardly used ove the years, left it at my church and cut there lawn every 2-3 weeks during the summers.
    the battery was dead, and it needed the belts replaced, so he bought like it was for dirt cheap. I paid, $1450 for it.
    anyway, he calls this morning, he charged the battery, but said it sounded like the motor was "seized", the start was trying to turn it over, but couldn't. i found it strange, of th elife of the engine, i haven't even come close to using 1/3 of it. i told him to take the plugs out, spray a lubricant, and see if it turns. its been a few months since it ran. he calls me back and says with the plugs out, it spins totally easy, and has "no compression". i'm no genius, but would't the plugs removed ofcourse have no compression?
    would the wrong spark plugs keep the engine from comleteing one turn, if they're maybe too long. i took out the originals, to replace but when i got to the Local shop, i forgot them in my truck and never compared them. the guy was confident that was what i needed, so i never bothered to compare (stupid onmy part, yes).

    what i'm asking is, is the the layout of the head chamber, so close that a longer plug would prevent 1 turn of the crank?

  4. Elkbow

    Elkbow LawnSite Member
    Messages: 59

    I would guess that either the piston is hitting the plug, or the starter might be bad. Sorry, but I can't tell you how close the piston get's to the "correct" plug.
  5. fga

    fga LawnSite Silver Member
    Messages: 2,449

    that's what it appears, huh Elk. The thing is i don't have it in font of me, he wants to bring it by tomorrow.
    wouldn't the engine turn over with the key, without the plugs in?
  6. pugs

    pugs LawnSite Gold Member
    Messages: 3,025

    Yah, it should spin like crazy. Did he replace the battery or just try to charge up a really old one? Get a new battery in it, make sure the right spark plugs are in it. If you need to get some, write down the model of the engine and take that to the auto parts store. As long as they have a Champion book there they should be able to look under briggs and get you the right one. That should get it running again unless there are other issues.
  7. fga

    fga LawnSite Silver Member
    Messages: 2,449

    no, he just charged the old one. i'll get the scoop myself tomorrow, see what's up with it. Bet i get it runnin':)
  8. Restrorob

    Restrorob LawnSite Fanatic
    Messages: 11,029

    Adam, I wouldn't think so, As you see the plugs go into the side of the head not on top in the piston area.
    On these units with the battery in the rear it is vary critical that the battery is in top condition because the positive cable is so long.
    I would suggest a new battery as pugs said and the proper spark plugs which is a champion RJ19LM and it should pop right off.

    Good Luck
  9. fga

    fga LawnSite Silver Member
    Messages: 2,449

    thanks for your help.
    i'll follow up tomorrow.
  10. fga

    fga LawnSite Silver Member
    Messages: 2,449

    follow up,
    guy dropped off the machine this evening.
    told me it felt seized, so he put a prybar on the flywheel nut :)nono: ).... then attempted to turn the key and it turns like totally free, like no compression.:hammerhead:
    I pulled off both heads and neither piston is moving. Now how bad is the situation? is it possible he broke BOTH connecting rods wrenching it?

    i know this is my fault either way, should have taken out the plugs, and sprayed a lubricant in there before it left my possesion.. i don't understand why someone would apply that much pressure though.
    i have diagrams and part costs, con-rods $30 a piece. is it really involved for the average wrench turner?

    also, can this engine be taken apart in 2 pieces. could i leave the bottom block/pan on the machine and take the top off? would the con rod/crankshaft be right there in the open to work on?

    i could be way off, i'm no internal engine guy at all, not on this scale.

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