Engine Rebuild

Discussion in 'Mechanic and Repair' started by Kkane97, Jul 6, 2012.

  1. Kkane97

    Kkane97 LawnSite Senior Member
    Posts: 676

    Instead of posting individual thread like I have been for problems with this motor, I will just post them all into this thread. So I solved the spark issue, new coil I dont know what was wrong with the other one, but this one works so all is good spark wise.

    I finished rebuilding the top end finally today, torqued the head and filled it with oil and gas and went to start it, nothing not even a pop. My dad said it would be ok to try a squirt or to of starting fluid, no pop. So I check the spark, all is good. Spark plug sparking all good. gas in the float bowl, check. Compression... 30 lbs :realmad: . If I remember right in cars, compression should be near 100lbs well I only have 30 mind you it is a small engine but IMO it just doesnt seem right.

    So to you guys does my compression seem wrong, or really bad? Could that explain why I wouldnt even get a pop from the motor?

    So far I have replaced a piston and rings ect...
    Brand new stens carb.
    new spark plug
    new gaskets except the carb and head gasket ie my theory on bad comp. (if you guys agree compression isnt right, Ill be ordering a new gasket tonight)
    new air filter
    new gas lines
    new to this motor coil
     
  2. piston slapper

    piston slapper LawnSite Platinum Member
    Posts: 4,240

    Slow down a little...you're not quite ready for new paint...
    What model engine do you have...
    You rebuilt the top end??? What did you do to the valves ? Clean..grind..adjust ?
    Did you get the cam and crank timed correctly?
    Sounds like you forgot the most important part...a service manual....
    Posted via Mobile Device
     
  3. laman

    laman LawnSite Senior Member
    Posts: 335

    You don't have enough compression for anything to happen. I would say you need 125 at minimum.
     
  4. Kkane97

    Kkane97 LawnSite Senior Member
    Posts: 676

    Sorry I forgot to post the info on the motor, every summer I try to rebuild something lying around our yard to get it running then sell it instead of bring it to the junkyard.

    this year was a baker tornado chipper/shredder model 612 - 3.5
    the motor is a tecumseh 3.5 hp model H35-45614S I havent had much luck finding a manual for it, but did find a nice breakdown on partstree.com

    I didnt do anything to the valves but wipe them down on top, they seat nice and tight when they are down by eye (is there a test for that)? The camshaft is timed correctly with the crankshaft, there are 2 notches that you line up accordingly on the gear on the camshaft and crankshaft. I reused the head gasket which i think would solve my compression problem because you know how they get squished after torquing the head down.


    Any other info available, thanks in advance for the help!
     
  5. dutch1

    dutch1 LawnSite Silver Member
    from Jayhawk
    Posts: 2,231

  6. Kkane97

    Kkane97 LawnSite Senior Member
    Posts: 676

    Thats why I just wanted to make one thread, I didnt want to be "that guy" so to speak lol
     
  7. BigFish

    BigFish LawnSite Gold Member
    Posts: 3,168

    So...... let me get this straight.
    You say you rebuilt this motor ?
    BUT :

    1. You reused the headgasket.
    2. You reused the carb gasket/s.
    3. You didn't do a thing to the valves.

    Did you measure the bore for wear, out of round, taper?.... Didn't think so.
    Did you hone/ deglaze the cyl.?..... Didn't think so.
    Did you check the rings for correct end gap?..... Didn't think so.

    "But it don't got no compression"

    Manuals are fairly easy to come by. I've recommended this site several times as a good place to get manuals and parts: http://www.mymowerparts.com/pdf/Tecumseh-Service-and-Repair-Manuals/
     
  8. Kkane97

    Kkane97 LawnSite Senior Member
    Posts: 676

    I just followed along with what my dad said to do apparently that was wrong, so last night I ordered a whole set of gaskets. I have tried and tried to find a manual for this motor or chipper but no luck
    Posted via Mobile Device
     
  9. BigFish

    BigFish LawnSite Gold Member
    Posts: 3,168

    How old are you?
     
  10. piston slapper

    piston slapper LawnSite Platinum Member
    Posts: 4,240

    Don't take it too personal....
    You're getting advice from a few master mechanics...that take nothing for granted...even when you do everything right...some problem that you've never seen can show up...
    The engine you're working on is very basic...any tecumseh 3 1/2 manual should get you straightened out...hang in there...
    Posted via Mobile Device
     

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