Stihl BR600 exposed

Discussion in 'Lawn Mowing' started by Richard Martin, Aug 23, 2007.

  1. Richard Martin

    Richard Martin LawnSite Fanatic
    Posts: 14,700

    My dealer gave me an old BR600 4 Mix engine to play around with. I have taken it apart and here it is. This pic shows the rotating assembly and most of the valve train. This engine is without a doubt a 4 stroke engine. The crank gear has 14 teeth and the cam/gear has 28 teeth. Of note is that the cam/gear is plastic. The remainder of the parts are steel or aluminum.

    MVC-481S.JPG
     
  2. Richard Martin

    Richard Martin LawnSite Fanatic
    Posts: 14,700

    This pic shows the "head" and the remainder of the valve train. The head is an intergal part of the entire engine (one casting) and is not removable. Of note here is the casting manufacturer's name. Mahle. Those of you who are familiar with engines will recognize this name.

    MVC-483S.JPG
     
  3. Richard Martin

    Richard Martin LawnSite Fanatic
    Posts: 14,700

    Here is a pic of the problem Stihl had with early engines. If you look inside the intake port you can see the valve guide sticking down inside the port. It should be up near the top of the port. If the guide comes down too far engine failure occurs.

    MVC-485S.JPG
     
  4. Richard Martin

    Richard Martin LawnSite Fanatic
    Posts: 14,700

    Here is a pic of Stihl's secret power valve. This is a prototype valve that is rarely seen in the field.

    MVC-482S.JPG
     
  5. Richard Martin

    Richard Martin LawnSite Fanatic
    Posts: 14,700

    That valve is actually the bottom half of the exhaust valve. It snapped in half and buried itself in the top of the piston.
     
  6. Tharrell

    Tharrell LawnSite Silver Member
    Posts: 2,964

    Powervalve!!! What will they think of next.That was a good one!
     
  7. sawman65

    sawman65 LawnSite Senior Member
    Posts: 751

    they make plastics stronger than steel nowdays lol.and i have never seen any valve guides drop.all i have seen is people using the wrong oil ie. not stihl oil. and have the valve stick open.and that my friend is what caused the valve to break and lodge in the top of the piston. i was one of the frist to have the 600's or the 4-mix in general on the east cost.if you have any questions call mid atlantic stihl.your dealer has the #. but he wont give it to you cause he has broken his contract with stihl. and will be reported
     
  8. Richard Martin

    Richard Martin LawnSite Fanatic
    Posts: 14,700

    He had about a dozen of them sitting there in a box. All of them had the dropped intake guide just like is shown in the pic. Then he showed me my new engine and the guides were both back up at the top. BTW, I didn't say the guide caused the valve to break, my non friend.

    And that dealer's name is....????
     
  9. lawnboy dan

    lawnboy dan LawnSite Gold Member
    Posts: 3,712

    i doubt the use of wrong oil would cause this type of failure . but i can see the importance of preventing buildup on the valves in this type of engine. i think a high quality syth oil is mandatory in this engine. a rep told me the ultra oil was developed just for these 4 mix engines. i hope the plastic cams hold up better than briggs and techumche does. i have had 2 fail me this season on low hrs engines
     
  10. outlaw1960

    outlaw1960 LawnSite Senior Member
    from denver
    Posts: 307

    Mahle, they make the filters for my Porsche, lol
     

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