new here, Hello all,and I Have a valve problem?!?!?!

Discussion in 'Mechanic and Repair' started by bigabe82, Sep 28, 2009.

  1. bigabe82

    bigabe82 LawnSite Member
    Posts: 13

    How's it going guys? I've been watching everyone Else's problems for a month or so and Yall guys(and girl) come up with some great solutions for 'em. I haven't stumbled across any quiet like mine though. I'll make this as short as possible.

    Kohler command 15.5 hp(on a craftsman 917271011). Bought mower for $25 on a good deal. Guy got rid of it because it developed a major problem of course. Upon starting(or the attempt of) you would have to seriously play with the throttle/choke lever(throttle and choke are on same lever, all the way up for choke...but I know yall knew that). I'd have to fully choke it, throw it all the way down upon fist sign of ignition, bring it right back up within a half a second, then make sure it is dead perfect on 3/4 to 7/8 choke. Anymore, any less results in engine dying! No throttle whatsoever is allowed by engine. So I take it apart and check/completely clean: carb, throttle/choke cable and lever, spark plug,fuel filter, gas cap, valves, piston(visual inspection, still in case, on the piston) safety switches(just in case), fuel shutoff/anti-dieseling solenoid and flywheel key.
    Well the flywheel key was sheared but that was from me trying to mess with starting it so much that it kept kicking back and spinning opposite the rotation of the normal rotation. So I replaced the key and sheared it again. I replaced it one more time and this one hasn't sheared yet. So now that's done, I have the head pulled and have had it pulled about 13 times(seriously)and put it back on and noticed that the rocker arms(non-adjustable valve type) are supposed to be screwed down all the way. Well, as I do this, the push rods and valves tighten up with like 1/4 of an inch of screw left to tighten. So as I tighten the rocker arm screws all the way down, it begins to compress the valves. I can even have the engine like 10 degrees past top dead center and this will happen. Doesn't matter, top dead center or not, the valves have a constant, and quiet large pressure on them. This has to be the original problem. Leaky or open valves seem to cause this condition all over this forum but what could make both of them constantly compress like that????? oh, while both valves are compressed, at least they still move like they should, exhaust opens more when it should and intake moves more when it should. Any help would be awesome and greatly appreciated!! Don't know what to do :cry: :hammerhead:
     
  2. bigabe82

    bigabe82 LawnSite Member
    Posts: 13

    (sorry, didn't add this and couldn't figure out how to edit)........and when I say they move like they should, I mean when I spin the flywheel, but that's on top of still having that pressure on 'em. and My Engine is a kohler cv15s or cv16s
     
  3. VegetiveSteam

    VegetiveSteam LawnSite Senior Member
    Posts: 297

    Your engine has hydraulic lifters in it and since the rocker arms have been loosened the lifters have extended all the way out. Before you can tighten the rocker arms back down the lifters need to have all the oil bled out of them. The best way to do that is to remove them but that will require taking the head off again. If you're not in a big hurry tighten everything down and let it sit for a few days. They will eventually bleed down.
     
  4. Restrorob

    Restrorob LawnSite Fanatic
    Posts: 11,024

    Adding to VS's post, If you tried to start the engine right after tightening the rockers there is a good chance the valves hit the piston. This can cause bent valves and or push-rods.
     
  5. bigabe82

    bigabe82 LawnSite Member
    Posts: 13

    Thank yall so much for responding!!:clapping:ok, so, just letting it sit for two or three days, completely assembled, and they'll bleed themselves? that would be nice. And when it would run, it'd run and sound like it was popping alot, the whole time actually. What do yall think the original problem was? And the valves still seat properly and no scratches or pitts on the piston or valves. I guess the original problem must have been a sheared flywheel key. it sounded like thrown timing and thats what the keyway is, so I guess I answered that one.:dizzy:
     
  6. bigabe82

    bigabe82 LawnSite Member
    Posts: 13

    so that's def it huh?
     
  7. Restrorob

    Restrorob LawnSite Fanatic
    Posts: 11,024

    Well,

    Once you get the lifters bled down so the valves operate properly, See how it runs. If you still have problems post back, I leave them sat overnight and haven't had any issues......
     
  8. bigabe82

    bigabe82 LawnSite Member
    Posts: 13

    10-4. I'll do that first thing in the morning and get back to you. I looked at the schematics and the hyd. lifters don't look so hard to remove. Flip over the engine and take off the oil pump. So once I do that, I'll be back beggin' for help. Thanks alot man. I really do appreciate it!!:drinkup:
     
  9. bigabe82

    bigabe82 LawnSite Member
    Posts: 13

    ok,I just went ahead and pulled the head again. What's that process on bleeding those bad boys??
     
  10. Restrorob

    Restrorob LawnSite Fanatic
    Posts: 11,024

    Stand them up and with a 1/4" socket on a nut driver push down on the center of the lifter where the push-rod rides, Oil will squeeze out the top and side holes. Once the top of the lifter stops moving it's empty enough to be re-installed.

    You don't have to do anything with the oil pump in regards to bleeding the lifters down.

    BTW,

    Since you've had this head off sooo many times, Did you replace the head gasket each time ?
     

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